"IO" -> "System".

Get rid of the separate opt-in IO class and replace it with a core
System class.

- Remove wren_io.c, wren_io.h, and io.wren.
- Remove the flags that disable it.
- Remove the overloads for print() with different arity. (It was an
  experiment, but I don't think it's that useful.)
- Remove IO.read(). That will reappear using libuv in the CLI at some
  point.
- Remove IO.time. Doesn't seem to have been used.
- Update all of the tests, docs, etc.

I'm sorry for all the breakage this causes, but I think "System" is a
better name for this class (it makes it natural to add things like
"System.gc()") and frees up "IO" for referring to the CLI's IO module.

README.md

@@ -4,11 +4,11 @@ Think Smalltalk in a Lua-sized package with a dash of Erlang and wrapped up in
 a familiar, modern [syntax][].
 
 ```dart
-IO.print("Hello, world!")
+System.print("Hello, world!")
 
 class Wren {
   flyTo(city) {
-    IO.print("Flying to ", city)
+    System.print("Flying to ", city)
   }
 }
 
@@ -16,7 +16,7 @@ var adjectives = Fiber.new {
   ["small", "clean", "fast"].each {|word| Fiber.yield(word) }
 }
 
-while (!adjectives.isDone) IO.print(adjectives.call())
+while (!adjectives.isDone) System.print(adjectives.call())
 ```
 
  *  **Wren is small.** The VM implementation is under [4,000 semicolons][src].

builtin/core.wren

@@ -213,3 +213,38 @@ class MapValueSequence is Sequence {
 }
 
 class Range is Sequence {}
+
+class System {
+  static print() {
+    writeString_("\n")
+  }
+
+  static print(obj) {
+    writeObject_(obj)
+    writeString_("\n")
+    return obj
+  }
+
+  static printAll(sequence) {
+    for (object in sequence) writeObject_(object)
+    writeString_("\n")
+  }
+
+  static write(obj) {
+    writeObject_(obj)
+    return obj
+  }
+
+  static writeAll(sequence) {
+    for (object in sequence) writeObject_(object)
+  }
+
+  static writeObject_(obj) {
+    var string = obj.toString
+    if (string is String) {
+      writeString_(string)
+    } else {
+      writeString_("[invalid toString]")
+    }
+  }
+}

builtin/io.wren

@@ -1,101 +0,0 @@
-class IO {
-  static print {
-    writeString_("\n")
-  }
-
-  static print(obj) {
-    writeObject_(obj)
-    writeString_("\n")
-    return obj
-  }
-
-  static print(a1, a2) {
-    printAll([a1, a2])
-  }
-
-  static print(a1, a2, a3) {
-    printAll([a1, a2, a3])
-  }
-
-  static print(a1, a2, a3, a4) {
-    printAll([a1, a2, a3, a4])
-  }
-
-  static print(a1, a2, a3, a4, a5) {
-    printAll([a1, a2, a3, a4, a5])
-  }
-
-  static print(a1, a2, a3, a4, a5, a6) {
-    printAll([a1, a2, a3, a4, a5, a6])
-  }
-
-  static print(a1, a2, a3, a4, a5, a6, a7) {
-    printAll([a1, a2, a3, a4, a5, a6, a7])
-  }
-
-  static print(a1, a2, a3, a4, a5, a6, a7, a8) {
-    printAll([a1, a2, a3, a4, a5, a6, a7, a8])
-  }
-
-  static print(a1, a2, a3, a4, a5, a6, a7, a8, a9) {
-    printAll([a1, a2, a3, a4, a5, a6, a7, a8, a9])
-  }
-
-  static print(a1, a2, a3, a4, a5, a6, a7, a8, a9, a10) {
-    printAll([a1, a2, a3, a4, a5, a6, a7, a8, a9, a10])
-  }
-
-  static print(a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11) {
-    printAll([a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11])
-  }
-
-  static print(a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12) {
-    printAll([a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12])
-  }
-
-  static print(a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13) {
-    printAll([a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13])
-  }
-
-  static print(a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14) {
-    printAll([a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14])
-  }
-
-  static print(a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14, a15) {
-    printAll([a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14, a15])
-  }
-
-  static print(a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14, a15, a16) {
-    printAll([a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14, a15, a16])
-  }
-
-  static printAll(sequence) {
-    for (object in sequence) writeObject_(object)
-    writeString_("\n")
-  }
-
-  static write(obj) {
-    writeObject_(obj)
-    return obj
-  }
-
-  static read(prompt) {
-    if (!(prompt is String)) Fiber.abort("Prompt must be a string.")
-    write(prompt)
-    return read()
-  }
-
-  static writeObject_(obj) {
-    var string = obj.toString
-    if (string is String) {
-      writeString_(string)
-    } else {
-      writeString_("[invalid toString]")
-    }
-  }
-
-  foreign static writeString_(string)
-  foreign static clock
-  foreign static time
-  foreign static read()
-}

doc/site/classes.markdown

@@ -25,7 +25,7 @@ To let our unicorn do stuff, we need to give it methods.
     :::dart
     class Unicorn {
       prance() {
-        IO.print("The unicorn prances in a fancy manner!")
+        System.print("The unicorn prances in a fancy manner!")
       }
     }
 
@@ -35,7 +35,7 @@ parameters, put their names inside the parentheses:
     :::dart
     class Unicorn {
       prance(where, when) {
-        IO.print("The unicorn prances in " + where + " at " + when)
+        System.print("The unicorn prances in " + where + " at " + when)
       }
     }
 
@@ -49,15 +49,15 @@ fine:
     :::dart
     class Unicorn {
       prance() {
-        IO.print("The unicorn prances in a fancy manner!")
+        System.print("The unicorn prances in a fancy manner!")
       }
 
       prance(where) {
-        IO.print("The unicorn prances in " + where)
+        System.print("The unicorn prances in " + where)
       }
 
       prance(where, when) {
-        IO.print("The unicorn prances in " + where + " at " + when)
+        System.print("The unicorn prances in " + where + " at " + when)
       }
     }
 
@@ -83,7 +83,7 @@ Many methods on a class exist to expose or compute some property of the object.
 For example:
 
     :::dart
-    IO.print("string".count) // "6".
+    System.print("string".count) // "6".
 
 These *getters* are just another kind of method—one without a parameter
 list. You can define them like so:
@@ -152,12 +152,12 @@ You can define operators in your class like so:
     class Unicorn {
       // Infix:
       +(other) {
-        IO.print("Adding to a unicorn?")
+        System.print("Adding to a unicorn?")
       }
 
       // Prefix:
       ! {
-        IO.print("Negating a unicorn?!")
+        System.print("Negating a unicorn?!")
       }
     }
 
@@ -191,7 +191,7 @@ like so:
     :::dart
     class Unicorn {
       construct new(name, color) {
-        IO.print("My name is " + name + " and I am " + color + ".")
+        System.print("My name is " + name + " and I am " + color + ".")
       }
     }
 
@@ -210,7 +210,7 @@ and each can clarify how it creates the instance:
     :::dart
     class Unicorn {
       construct brown(name) {
-        IO.print("My name is " + name + " and I am brown.")
+        System.print("My name is " + name + " and I am brown.")
       }
     }
 
@@ -326,13 +326,13 @@ not the instance. They can be used in *both* instance and static methods.
 Just like instance fields, static fields are initially `null`:
 
     :::dart
-    IO.print(Foo.bar) // null.
+    System.print(Foo.bar) // null.
 
 They can be used from static methods:
 
     :::dart
     Foo.set("foo")
-    IO.print(Foo.bar) // foo.
+    System.print(Foo.bar) // foo.
 
 And also instance methods. When you do so, there is still only one static field
 shared among all instances of the class:
@@ -342,7 +342,7 @@ shared among all instances of the class:
     var foo2 = Foo.new()
 
     foo1.setFromInstance("updated")
-    IO.print(foo2.baz) // updated.
+    System.print(foo2.baz) // updated.
 
 ## Inheritance
 
@@ -381,7 +381,7 @@ This also means constructors are not inherited:
     :::dart
     class Unicorn {
       this new(name) {
-        IO.print("My name is " + name + ".")
+        System.print("My name is " + name + ".")
       }
     }
 
@@ -398,7 +398,7 @@ This means you can do `super` calls inside a constructor:
     :::dart
     class Unicorn {
       this new(name) {
-        IO.print("My name is " + name + ".")
+        System.print("My name is " + name + ".")
       }
     }
 

doc/site/control-flow.markdown

@@ -31,7 +31,7 @@ The simplest branching statement, `if` lets you conditionally skip a chunk of
 code. It looks like this:
 
     :::dart
-    if (ready) IO.print("go!")
+    if (ready) System.print("go!")
 
 That evaluates the parenthesized expression after `if`. If it's true, then the
 statement after the condition is evaluated. Otherwise it is skipped. Instead of
@@ -39,23 +39,23 @@ a statement, you can have a [block](syntax.html#blocks):
 
     :::dart
     if (ready) {
-      IO.print("getSet")
-      IO.print("go!")
+      System.print("getSet")
+      System.print("go!")
     }
 
 You may also provide an `else` branch. It will be executed if the condition is
 false:
 
     :::dart
-    if (ready) IO.print("go!") else IO.print("not ready!")
+    if (ready) System.print("go!") else System.print("not ready!")
 
 And, of course, it can take a block too:
 
     :::dart
     if (ready) {
-      IO.print("go!")
+      System.print("go!")
     } else {
-      IO.print("not ready!")
+      System.print("not ready!")
     }
 
 ## While statements
@@ -100,7 +100,7 @@ That's what `for` is for. It looks like this:
 
     :::dart
     for (beatle in ["george", "john", "paul", "ringo"]) {
-      IO.print(beatle)
+      System.print(beatle)
     }
 
 A `for` loop has three components:
@@ -124,7 +124,7 @@ keyword all by itself. That will immediately exit out of the nearest enclosing
 
     :::dart
     for (i in [1, 2, 3, 4]) {
-      IO.print(i)
+      System.print(i)
       if (i == 3) break
     }
 
@@ -138,7 +138,7 @@ sequence of numbers, or loop a number of times. For that, you can create a
 
     :::dart
     for (i in 1..100) {
-      IO.print(i)
+      System.print(i)
     }
 
 This loops over the numbers from 1 to 100, including 100 itself. If you want to
@@ -146,7 +146,7 @@ leave off the last value, use three dots instead of two:
 
     :::dart
     for (i in 1...100) {
-      IO.print(i)
+      System.print(i)
     }
 
 This looks like some special "range" syntax in the `for` loop, but it's
@@ -168,7 +168,7 @@ When you write a loop like this:
 
     :::dart
     for (i in 1..100) {
-      IO.print(i)
+      System.print(i)
     }
 
 Wren sees it something like this:
@@ -178,7 +178,7 @@ Wren sees it something like this:
     var seq_ = 1..100
     while (iter_ = seq_.iterate(iter_)) {
       var i = seq_.iteratorValue(iter_)
-      IO.print(i)
+      System.print(i)
     }
 
 First, Wren evaluates the sequence expression and stores it in a hidden

doc/site/core/bool.markdown

@@ -9,10 +9,9 @@ Boolean values. There are two instances, `true` and `false`.
 
 Returns the logical complement of the value.
 
-    > !true
-    false
-    > !false
-    true
+    :::dart
+    System.print(!true) // "false".
+    System.print(!false) // "true".
 
 ### toString
 

doc/site/core/class.markdown

@@ -15,14 +15,14 @@ The superclass of this class.
     class Crustacean {}
     class Crab is Crustacean {}
 
-    IO.print(Crab.supertype)        // "Crustacean"
+    System.print(Crab.supertype) // "Crustacean".
 
 A class with no explicit superclass implicitly inherits Object:
 
     :::dart
-    IO.print(Crustacean.supertype)  // "Object"
+    System.print(Crustacean.supertype) // "Object".
 
 Object forms the root of the class hierarchy and has no supertype:
 
     :::dart
-    IO.print(Object.supertype)  // "null"
+    System.print(Object.supertype) // "null".

doc/site/core/fiber.markdown

@@ -10,7 +10,7 @@ fiber is run. Does not immediately start running the fiber.
 
     :::dart
     var fiber = Fiber.new {
-      IO.print("I won't get printed")
+      System.print("I won't get printed")
     }
 
 ## Static Methods
@@ -34,14 +34,14 @@ here means the last fiber that was started using `call` and not `run`.
 
     :::dart
     var fiber = Fiber.new {
-      IO.print("Before yield")
+      System.print("Before yield")
       Fiber.yield()
-      IO.print("After yield")
+      System.print("After yield")
     }
 
-    fiber.call()            // "Before yield"
-    IO.print("After call")  // "After call"
-    fiber.call()            // "After yield"
+    fiber.call()                // "Before yield"
+    System.print("After call")  // "After call"
+    fiber.call()                // "After yield"
 
 When resumed, the parent fiber's `call()` method returns `null`.
 
@@ -50,7 +50,7 @@ If a yielded fiber is resumed by calling `call()` or `run()` with an argument,
 
     :::dart
     var fiber = Fiber.new {
-      IO.print(Fiber.yield()) // "value"
+      System.print(Fiber.yield()) // "value"
     }
 
     fiber.call()        // Run until the first yield.
@@ -65,7 +65,7 @@ later.
 
     :::dart
     Fiber.yield()
-    IO.print("this does not get reached")
+    System.print("this does not get reached")
 
 ### Fiber.**yield**(value)
 
@@ -77,7 +77,7 @@ Similar to `Fiber.yield` but provides a value to return to the parent fiber's
       Fiber.yield("value")
     }
 
-    IO.print(fiber.call()) // "value"
+    System.print(fiber.call()) // "value"
 
 ## Methods
 
@@ -87,9 +87,9 @@ Starts or resumes the fiber if it is in a paused state.
 
     :::dart
     var fiber = Fiber.new {
-      IO.print("Fiber called")
+      System.print("Fiber called")
       Fiber.yield()
-      IO.print("Fiber called again")
+      System.print("Fiber called again")
     }
 
     fiber.call() // Start it.
@@ -103,7 +103,7 @@ If the called fiber is resuming from a yield, the `yield()` method returns
 
     :::dart
     var fiber = Fiber.new {
-      IO.print(Fiber.yield())
+      System.print(Fiber.yield())
     }
 
     fiber.call()
@@ -116,7 +116,7 @@ Invokes the fiber or resumes the fiber if it is in a paused state and sets
 
     :::dart
     var fiber = Fiber.new {
-      IO.print(Fiber.yield())
+      System.print(Fiber.yield())
     }
 
     fiber.call()

doc/site/core/fn.markdown

@@ -13,7 +13,7 @@ argument](../functions.html#block-arguments) to some other method.
 
     :::dart
     var fn = Fn.new {
-      IO.print("The body")
+      System.print("The body")
     }
 
 It is a runtime error if `function` is not a function.
@@ -25,8 +25,8 @@ It is a runtime error if `function` is not a function.
 The number of arguments the function requires.
 
     :::dart
-    IO.print(Fn.new {}.arity)             // 0.
-    IO.print(Fn.new {|a, b, c| a }.arity) // 3.
+    System.print(Fn.new {}.arity)             // 0.
+    System.print(Fn.new {|a, b, c| a }.arity) // 3.
 
 ### **call**(args...)
 
@@ -34,7 +34,7 @@ Invokes the function with the given arguments.
 
     :::dart
     var fn = Fn.new { |arg|
-      IO.print(arg)
+      System.print(arg)
     }
 
     fn.call("Hello world") // Prints "Hello world".

doc/site/core/index.markdown

@@ -20,6 +20,6 @@ All Wren source files automatically have access to the following classes:
 * [Range](range.html)
 * [Sequence](sequence.html)
 * [String](string.html)
-* [IO](io.html)
+* [System](system.html)
 
 [embedding]: ../embedding-api.html

doc/site/core/io.markdown

@@ -1,60 +0,0 @@
-^title IO Class
-^category core
-
-The IO class can be used to read and write to and from the console.
-
-## Static Methods
-
-### IO.**print**(objects...)
-
-Prints a series of objects to the console followed by a newline. Each object is
-converted to a string by calling `toString` on it. This is overloaded to
-support up to 16 objects. To pass more, use `printAll()`.
-
-  > IO.print("I like bananas")
-  I like bananas
-  > IO.print("Oranges", 10)
-  Oranges10
-
-### IO.**printAll**(sequence)
-
-Iterates over [sequence] and prints each element, then prints a single newline
-at the end. Each element is converted to a string by calling `toString` on it.
-
-  > IO.printAll([1, [2, 3], 4])
-  1[2, 3]4
-
-### IO.**write**(object)
-
-Prints a single value to the console, but does not print a newline character
-afterwards. Converts the value to a string by calling `toString` on it.
-
-  > IO.write(4 + 5)
-  9>
-
-In the above example, the result of `4 + 5` is printed, and then the prompt is
-printed on the same line because no newline character was printed afterwards.
-
-### IO.**read**()
-
-Reads in a line of text from stdin. Note that the returned text includes the
-trailing newline.
-
-  > var name = IO.read()
-  John
-  > IO.print("Hello " + name + "!")
-  Hello John
-  !
-  >
-
-### IO.**read**(prompt)
-
-Displays `prompt` then reads in a line of text from stdin. Note that the
-returned text includes the trailing newline.
-
-  > var name = IO.read("Enter your name: ")
-  Enter your name: John
-  > IO.print("Hello " + name + "!")
-  Hello John
-  !
-  >

doc/site/core/list.markdown

@@ -26,14 +26,14 @@ Inserts the `item` at `index` in the list.
     :::dart
     var list = ["a", "b", "c", "d"]
     list.insert(1, "e")
-    IO.print(list) // "[a, e, b, c, d]"
+    System.print(list) // "[a, e, b, c, d]".
 
 The `index` may be one past the last index in the list to append an element.
 
     :::dart
     var list = ["a", "b", "c"]
     list.insert(3, "d")
-    IO.print(list) // "[a, b, c, d]"
+    System.print(list) // "[a, b, c, d]".
 
 If `index` is negative, it counts backwards from the end of the list. It bases this on the length of the list *after* inserted the element, so that `-1` will append the element, not insert it before the last element.
 
@@ -41,12 +41,12 @@ If `index` is negative, it counts backwards from the end of the list. It bases t
     var list = ["a", "b"]
     list.insert(-1, "d")
     list.insert(-2, "c")
-    IO.print(list) // "[a, b, c, d]"
+    System.print(list) // "[a, b, c, d]".
 
 Returns the inserted item.
 
     :::dart
-    IO.print(["a", "c"].insert(1, "b")) // "b".
+    System.print(["a", "c"].insert(1, "b")) // "b".
 
 It is a runtime error if the index is not an integer or is out of bounds.
 
@@ -64,11 +64,11 @@ are shifted up to fill in where the removed element was.
     :::dart
     var list = ["a", "b", "c", "d"]
     list.removeAt(1)
-    IO.print(list) // "[a, c, d]".
+    System.print(list) // "[a, c, d]".
 
 Returns the removed item.
 
-    IO.print(["a", "b", "c"].removeAt(1)) // "b".
+    System.print(["a", "b", "c"].removeAt(1)) // "b".
 
 It is a runtime error if the index is not an integer or is out of bounds.
 
@@ -79,7 +79,7 @@ the end of the list where `-1` is the last element.
 
     :::dart
     var list = ["a", "b", "c"]
-    IO.print(list[1]) // "b".
+    System.print(list[1]) // "b".
 
 It is a runtime error if the index is not an integer or is out of bounds.
 
@@ -91,6 +91,6 @@ backwards from the end of the list where `-1` is the last element.
     :::dart
     var list = ["a", "b", "c"]
     list[1] = "new"
-    IO.print(list) // "[a, new, c]".
+    System.print(list) // "[a, new, c]".
 
 It is a runtime error if the index is not an integer or is out of bounds.

doc/site/core/map.markdown

@@ -50,8 +50,8 @@ map, returns `null`.
 
     :::dart
     var map = {"george": "harrison", "ringo": "starr"}
-    IO.print(map["ringo"]) // "starr".
-    IO.print(map["pete"])  // "null".
+    System.print(map["ringo"]) // "starr".
+    System.print(map["pete"])  // "null".
 
 ### **[**key**]=**(value) operator
 

doc/site/core/null.markdown

@@ -7,5 +7,5 @@
 
 Returns `true`, since `null` is considered [false](../control-flow.html#truth).
 
-    > !null
-    true
+    :::dart
+    System.print(!null) // "true".

doc/site/core/num.markdown

@@ -132,9 +132,9 @@ from the beginning number to the ending number.
 
     :::dart
     var range = 1.2..3.4
-    IO.print(range.min)         // 1.2
-    IO.print(range.max)         // 3.4
-    IO.print(range.isInclusive) // true
+    System.print(range.min)         // 1.2
+    System.print(range.max)         // 3.4
+    System.print(range.isInclusive) // true
 
 ### **...**(other) operator
 
@@ -143,6 +143,6 @@ from the beginning number to the ending number not including the ending number.
 
     :::dart
     var range = 1.2...3.4
-    IO.print(range.min)         // 1.2
-    IO.print(range.max)         // 3.4
-    IO.print(range.isInclusive) // false
+    System.print(range.min)         // 1.2
+    System.print(range.max)         // 3.4
+    System.print(range.isInclusive) // false

doc/site/core/sequence.markdown

@@ -59,7 +59,7 @@ and counting the number of times the returned value evaluates to `true`.
 Iterates over the sequence, passing each element to the given `function`.
 
     :::dart
-    ["one", "two", "three"].each {|word| IO.print(word) }
+    ["one", "two", "three"].each {|word| System.print(word) }
 
 ### **isEmpty**
 
@@ -88,7 +88,7 @@ original sequence while it is iterated.
     :::dart
     var doubles = [1, 2, 3].map {|n| n * 2 }
     for (n in doubles) {
-      IO.print(n) // "2", "4", "6".
+      System.print(n) // "2", "4", "6".
     }
 
 The returned sequence is *lazy*. It only applies the mapping when you iterate
@@ -105,7 +105,7 @@ To force eager evaluation, just call `.toList` on the result.
     var numbers = [1, 2, 3]
     var doubles = numbers.map {|n| n * 2 }.toList
     numbers.add(4)
-    IO.print(doubles) // [2, 4, 6].
+    System.print(doubles) // [2, 4, 6].
 
 ### **reduce**(function)
 
@@ -142,7 +142,7 @@ function `predicate`. If it returns `false`, the element is skipped.
     :::dart
     var odds = (1..10).where {|n| n % 2 == 1 }
     for (n in odds) {
-      IO.print(n) // "1", "3", "5", "7", "9".
+      System.print(n) // "1", "3", "5", "7", "9".
     }
 
 The returned sequence is *lazy*. It only applies the filtering when you iterate
@@ -160,4 +160,4 @@ To force eager evaluation, just call `.toList` on the result.
     var numbers = [1, 2, 3, 4, 5, 6]
     var odds = numbers.where {|n| n % 2 == 1 }.toList
     numbers.add(7)
-    IO.print(odds) // [1, 3, 5].
+    System.print(odds) // [1, 3, 5].

doc/site/core/string.markdown

@@ -37,7 +37,7 @@ on strings *return* byte indexes too. So, for example, this does what you want:
     :::dart
     var metalBand = "Fäcëhämmër"
     var hPosition = metalBand.indexOf("h")
-    IO.print(metalBand[hPosition]) // "h"
+    System.print(metalBand[hPosition]) // "h"
 
 If you want to work with a string as a sequence numeric code points, call the
 `codePoints` getter. It returns a [Sequence](sequence.html) that decodes UTF-8
@@ -68,7 +68,7 @@ methods, the returned object also has a subscript operator that can be used to
 directly index bytes.
 
     :::dart
-    IO.print("hello".bytes[1]) // 101, for "e".
+    System.print("hello".bytes[1]) // 101, for "e".
 
 The `count` method on the returned sequence returns the number of bytes in the
 string. Unlike `count` on the string itself, it does not have to iterate over
@@ -83,15 +83,15 @@ single-character strings, this returns the numeric code point values.
 
     :::dart
     var string = "(ᵔᴥᵔ)"
-    IO.print(string.codePoints[0]) // 40, for "(".
-    IO.print(string.codePoints[4]) // 7461, for "ᴥ".
+    System.print(string.codePoints[0]) // 40, for "(".
+    System.print(string.codePoints[4]) // 7461, for "ᴥ".
 
 If the byte at `index` does not begin a valid UTF-8 sequence, or the end of the
 string is reached before the sequence is complete, returns `-1`.
 
     :::dart
     var string = "(ᵔᴥᵔ)"
-    IO.print(string.codePoints[2]) // -1, in the middle of "ᵔ".
+    System.print(string.codePoints[2]) // -1, in the middle of "ᵔ".
 
 ### **contains**(other)
 
@@ -132,7 +132,7 @@ for iterating over the *code points* in the string:
       codePoints.add(c)
     }
 
-    IO.print(codePoints) // ["(", "ᵔ", "ᴥ", "ᵔ", ")"].
+    System.print(codePoints) // ["(", "ᵔ", "ᴥ", "ᵔ", ")"].
 
 If the string contains any bytes that are not valid UTF-8, this iterates over
 those too, one byte at a time.
@@ -162,7 +162,7 @@ Check if the string is not equal to `other`.
 Returns a string containing the code point starting at byte `index`.
 
     :::dart
-    IO.print("ʕ•ᴥ•ʔ"[5]) // "ᴥ".
+    System.print("ʕ•ᴥ•ʔ"[5]) // "ᴥ".
 
 Since `ʕ` is two bytes in UTF-8 and `•` is three, the fifth byte points to the
 bear's nose.
@@ -171,7 +171,7 @@ If `index` points into the middle of a UTF-8 sequence or at otherwise invalid
 UTF-8, this returns a one-byte string containing the byte at that index:
 
     :::dart
-    IO.print("I ♥ NY"[3]) // One-byte string whose value is 153.
+    System.print("I ♥ NY"[3]) // One-byte string whose value is 153.
 
 It is a runtime error if `index` is greater than the number of bytes in the
 string.

doc/site/core/system.markdown

@@ -0,0 +1,43 @@
+^title System Class
+^category core
+
+The System class is a grab-bag of functionality exposed by the VM, mostly for
+use during development or debugging.
+
+## Static Methods
+
+### System.**print**()
+
+Prints a single newline to the console.
+
+### System.**print**(object)
+
+Prints [object] to the console followed by a newline. If not already a string,
+the object is converted to a string by calling `toString` on it.
+
+    :::dart
+    System.print("I like bananas") // Prints "I like bananas".
+
+### System.**printAll**(sequence)
+
+Iterates over [sequence] and prints each element, then prints a single newline
+at the end. Each element is converted to a string by calling `toString` on it.
+
+    :::dart
+    System.printAll([1, [2, 3], 4]) // Prints "1[2, 3]4".
+
+### System.**write**(object)
+
+Prints a single value to the console, but does not print a newline character
+afterwards. Converts the value to a string by calling `toString` on it.
+
+    :::dart
+    System.write(4 + 5) // Prints "9".
+
+In the above example, the result of `4 + 5` is printed, and then the prompt is
+printed on the same line because no newline character was printed afterwards.
+
+### System.**clock**
+
+Returns the number of seconds (including fractional seconds) since the program
+was started. This is usually used for benchmarking.

doc/site/embedding-api.markdown

@@ -70,7 +70,7 @@ You can tell the VM to execute a string of Wren source code like so:
     :::c
     WrenInterpretResult result = wrenInterpret(vm,
         "<where>",
-        "IO.print(\"Hi!\")");
+        "System.print(\"Hi!\")");
 
 The first string parameter is a "source path". It's just an arbitrary string that describes where the source code is from. It's what shows up in stack traces if a runtime error occurs in the code. It can be whatever you want as long as it's not `NULL`.
 

doc/site/error-handling.markdown

@@ -108,7 +108,7 @@ For example, if you run this program:
     }
 
     var error = fiber.try()
-    IO.print("Caught error: ", error)
+    System.print("Caught error: " + error)
 
 It prints:
 
@@ -120,7 +120,7 @@ usual. When a fiber has been aborted because of a runtime error, you can also
 get the error from the fiber object. Continuing the above example:
 
     :::dart
-    IO.print(fiber.error)
+    System.print(fiber.error)
 
 This also prints:
 

doc/site/expressions.markdown

@@ -29,7 +29,7 @@ Wren is object-oriented, so most code consists of method calls. Most of them
 look like so:
 
     :::dart
-    IO.print("hello")
+    System.print("hello")
     items.add("another")
     items.insert(1, "value")
 
@@ -61,7 +61,7 @@ argument](functions.html#block-arguments):
 
     :::dart
     blondie.callMeAt(867, 5309) {
-      IO.print("This is the body!")
+      System.print("This is the body!")
     }
 
 Semantically, all method calls work like so:
@@ -98,7 +98,7 @@ call:
     :::dart
     class Base {
       method {
-        IO.print("base method")
+        System.print("base method")
       }
     }
 
@@ -114,7 +114,7 @@ base class constructor:
     :::dart
     class Base {
       this new(arg) {
-        IO.print("base constructor got ", arg)
+        System.print("base constructor got " + arg)
       }
     }
 
@@ -218,16 +218,16 @@ A `&&` ("logical and") expression evaluates the left-hand argument. If it's
 and returns the right-hand argument.
 
     :::dart
-    IO.print(false && 1)  // false
-    IO.print(1 && 2)      // 2
+    System.print(false && 1)  // false
+    System.print(1 && 2)      // 2
 
 An `||` ("logical or") expression is reversed. If the left-hand argument is
 [true](control-flow.html#truth), it's returned, otherwise the right-hand
 argument is evaluated and returned:
 
     :::dart
-    IO.print(false || 1)  // 1
-    IO.print(1 || 2)      // 1
+    System.print(false || 1)  // 1
+    System.print(1 || 2)      // 1
 
 ## The conditional operator `?:`
 
@@ -236,7 +236,7 @@ the little "if statement in the form of an expression" you know and love from C
 and its brethren.
 
     :::dart
-    IO.print(1 != 2 ? "math is sane" : "math is not sane!")
+    System.print(1 != 2 ? "math is sane" : "math is not sane!")
 
 It takes a condition expression, followed by `?`, followed by a then
 expression, a `:`, then an else expression. Just like `if`, it evaluates the

doc/site/fibers.markdown

@@ -28,7 +28,7 @@ using the `Fiber` class's constructor:
 
     :::dart
     var fiber = Fiber.new {
-      IO.print("This runs in a separate fiber.")
+      System.print("This runs in a separate fiber.")
     }
 
 Creating a fiber does not immediately run it. It's just a first class bundle of
@@ -48,7 +48,7 @@ until it passes control to another fiber. If it reaches the end of its body,
 it's considered *done*:
 
     :::dart
-    var fiber = Fiber.new { IO.print("Hi") }
+    var fiber = Fiber.new { System.print("Hi") }
     fiber.isDone // false
     fiber.call()
     fiber.isDone // true
@@ -71,16 +71,16 @@ You can make a fiber yield by calling the static `yield()` method on `Fiber`:
 
     :::dart
     var fiber = Fiber.new {
-      IO.print("fiber 1")
+      System.print("fiber 1")
       Fiber.yield()
-      IO.print("fiber 2")
+      System.print("fiber 2")
     }
 
-    IO.print("main 1")
+    System.print("main 1")
     fiber.call()
-    IO.print("main 2")
+    System.print("main 2")
     fiber.call()
-    IO.print("main 3")
+    System.print("main 3")
 
 This program prints:
 
@@ -105,7 +105,7 @@ of the `yield()` call:
     :::dart
     var fiber = Fiber.new {
       var result = Fiber.yield()
-      IO.print(result)
+      System.print(result)
     }
 
     fiber.call("discarded")
@@ -124,7 +124,7 @@ invoke the fiber:
       Fiber.yield("sent")
     }
 
-    IO.print(fiber.call())
+    System.print(fiber.call())
 
 This also prints "sent".
 

doc/site/functions.markdown

@@ -22,7 +22,7 @@ a method. At its simplest, it looks like this:
 
     :::dart
     blondie.callMe {
-      IO.print("This is the body!")
+      System.print("This is the body!")
     }
 
 Here we're invoking the `callMe` method on `blondie`. We're passing one
@@ -44,7 +44,7 @@ the block just like a regular argument list. For example:
 
     :::dart
     blondie.callMeAt(867, 5309) {
-      IO.print("This is the body!")
+      System.print("This is the body!")
     }
 
 Of course, you don't *have* to use a block argument to pass a function to a
@@ -62,7 +62,7 @@ class's constructor:
 
     :::dart
     var someFn = Fn.new {
-      IO.print("Hi!")
+      System.print("Hi!")
     }
 
 As you can see it takes a block argument too! All the constructor does it
@@ -87,7 +87,7 @@ method is dynamically-dispatched like any other, so you can define your own
     :::dart
     class FakeFn {
       call() {
-        IO.print("I'm feeling functional!")
+        System.print("I'm feeling functional!")
       }
     }
 
@@ -102,7 +102,7 @@ of the body, like so:
 
     :::dart
     blondie.callMe {|first, last|
-      IO.print("Hi, " + first + " " + last + "!")
+      System.print("Hi, " + first + " " + last + "!")
     }
 
 Here we're passing a function to `greet` that takes two parameters, `first` and
@@ -157,6 +157,6 @@ to`i`:
 
     :::dart
     var counter = Counter.create
-    IO.print(counter.call()) // Prints "1".
-    IO.print(counter.call()) // Prints "2".
-    IO.print(counter.call()) // Prints "3".
+    System.print(counter.call()) // Prints "1".
+    System.print(counter.call()) // Prints "2".
+    System.print(counter.call()) // Prints "3".

doc/site/getting-started.markdown

@@ -49,12 +49,12 @@ interactive mode. You can type in a line of code, and it will immediately
 execute it. Here's something to try:
 
     :::dart
-    IO.print("Hello, world!")
+    System.print("Hello, world!")
 
 Or a little more exciting:
 
     :::dart
-    for (i in 1..10) IO.print("Counting up ", i)
+    for (i in 1..10) System.print("Counting up " + i.toString)
 
 You can exit the interpreter using good old Ctrl-C or Ctrl-D, or just throw
 your computer to the ground and storm off.
@@ -80,10 +80,10 @@ your favorite text editor and paste this into it:
           y0 = y1
           iter = iter + 1
         }
-        IO.write(" .-:;+=xX$& "[iter])
+        System.write(" .-:;+=xX$& "[iter])
       }
 
-      IO.print("")
+      System.print("")
     }
 
 Now run:

doc/site/index.markdown

@@ -6,11 +6,11 @@ Think Smalltalk in a Lua-sized package with a dash of Erlang and wrapped up in
 a familiar, modern [syntax][].
 
     :::dart
-    IO.print("Hello, world!")
+    System.print("Hello, world!")
 
     class Wren {
       flyTo(city) {
-        IO.print("Flying to ", city)
+        System.print("Flying to " + city)
       }
     }
 
@@ -18,7 +18,7 @@ a familiar, modern [syntax][].
       ["small", "clean", "fast"].each {|word| Fiber.yield(word) }
     }
 
-    while (!adjectives.isDone) IO.print(adjectives.call())
+    while (!adjectives.isDone) System.print(adjectives.call())
 
  *  **Wren is small.** The VM implementation is under [4,000 semicolons][src].
     You can skim the whole thing in an afternoon. It's *small*, but not

doc/site/lists.markdown

@@ -59,14 +59,14 @@ existing element in the list using the subscript setter:
 
     :::dart
     hirsute[1] = "muttonchops"
-    IO.print(hirsute[1]) // muttonchops.
+    System.print(hirsute[1]) // muttonchops.
 
 It's an error to set an element that's out of bounds. To grow a list, you can
 use `add` to append a single item to the end:
 
     :::dart
     hirsute.add("goatee")
-    IO.print(hirsute.count) // 4.
+    System.print(hirsute.count) // 4.
 
 You can insert a new element at a specific position using `insert`:
 
@@ -84,9 +84,9 @@ back. Doing so counts back from the size of the list *after* it's grown by one:
     :::dart
     var letters = ["a", "b", "c"]
     letters.insert(3, "d")   // OK: inserts at end.
-    IO.print(letters)        // ["a", "b", "c", "d"]
+    System.print(letters)        // ["a", "b", "c", "d"]
     letters.insert(-2, "e")  // Counts back from size after insert.
-    IO.print(letters)        // ["a", "b", "c", "e", "d"]
+    System.print(letters)        // ["a", "b", "c", "e", "d"]
 
 ## Removing elements
 
@@ -97,15 +97,15 @@ gap:
     :::dart
     var letters = ["a", "b", "c", "d"]
     letters.removeAt(1)
-    IO.print(letters) // ["a", "c", "d"]
+    System.print(letters) // ["a", "c", "d"]
 
 The `removeAt` method returns the removed item:
 
     :::dart
-    IO.print(letters.removeAt(1)) // "c"
+    System.print(letters.removeAt(1)) // "c"
 
 If you want to remove everything from the list, you can clear it:
 
     :::dart
     hirsute.clear()
-    IO.print(hirsute) // []
+    System.print(hirsute) // []

doc/site/maps.markdown

@@ -58,7 +58,7 @@ To find the value associated with some key, again you use your friend the
 subscript operator:
 
     :::dart
-    IO.print(capitals["Idaho"]) // "Boise".
+    System.print(capitals["Idaho"]) // "Boise".
 
 If the key is present, this returns its value. Otherwise, it returns `null`. Of
 course, `null` itself can also be used as a value, so seeing `null` here
@@ -69,15 +69,15 @@ To tell definitively if a key exists, you can call `containsKey()`:
     :::dart
     var belief = {"nihilism": null}
 
-    IO.print(belief["nihilism"]) // "null" though key exists.
-    IO.print(belief["solipsism"]) // Also "null".
-    IO.print(belief.containsKey("nihilism")) // "true".
-    IO.print(belief.containsKey("solipsism")) // "false".
+    System.print(belief["nihilism"]) // "null" though key exists.
+    System.print(belief["solipsism"]) // Also "null".
+    System.print(belief.containsKey("nihilism")) // "true".
+    System.print(belief.containsKey("solipsism")) // "false".
 
 You can see how many entries a map contains using `count`:
 
     :::dart
-    IO.print(capitals.count) // "3".
+    System.print(capitals.count) // "3".
 
 ## Removing entries
 
@@ -86,12 +86,12 @@ entry you want to delete:
 
     :::dart
     capitals.remove("Maine")
-    IO.print(capitals.containsKey("Maine")) // "false".
+    System.print(capitals.containsKey("Maine")) // "false".
 
 If the key was found, this returns the value that was associated with it:
 
     :::dart
-    IO.print(capitals.remove("Georgia")) // "Atlanta".
+    System.print(capitals.remove("Georgia")) // "Atlanta".
 
 If the key wasn't in the map to begin with, `remove()` just returns `null`.
 
@@ -100,7 +100,7 @@ can just call `clear()`:
 
     :::dart
     capitals.clear()
-    IO.print(capitals.count) // "0".
+    System.print(capitals.count) // "0".
 
 [lists]: lists.html
 
@@ -120,14 +120,14 @@ If you want to see all of the key-value pairs in a map, the easiest way is to
 iterate over the keys and use each to look up its value:
 
     :::dart
-    var stateBirds = {
+    var birds = {
       "Arizona": "Cactus wren",
       "Hawaii": "Nēnē",
       "Ohio": "Northern Cardinal"
     }
 
-    for (state in stateBirds.keys) {
-      IO.print("The state bird of ", state, " is ", stateBirds[state])
+    for (state in birds.keys) {
+      System.print("The state bird of " + state + " is " + birds[state])
     }
 
 This program will print the three states and their birds. However, the *order*

doc/site/modules.markdown

@@ -173,7 +173,7 @@ like:
     import "shared"
 
     // shared.wren
-    IO.print("Shared!")
+    System.print("Shared!")
 
 Here, "a" and "b" both want to use "shared". If "shared" defines some top-level
 state, we only want a single copy of that in memory. To handle this, a module's
@@ -211,14 +211,14 @@ For example:
     import "a"
 
     // a.wren
-    IO.print("start a")
+    System.print("start a")
     import "b"
-    IO.print("end a")
+    System.print("end a")
 
     // b.wren
-    IO.print("start b")
+    System.print("start b")
     import "a"
-    IO.print("end b")
+    System.print("end b")
 
 This program runs successfully and prints:
 

doc/site/syntax.markdown

@@ -54,15 +54,15 @@ Newlines (`\n`) are meaningful in Wren. They are used to separate statements:
 
     :::dart
     // Two statements:
-    IO.print("hi") // Newline.
-    IO.print("bye")
+    System.print("hi") // Newline.
+    System.print("bye")
 
 Sometimes, though, a statement doesn't fit on a single line and jamming a
 newline in the middle would trip it up. To handle that, Wren has a very simple
 rule: It ignores a newline following any token that can't end a statement.
 
     :::dart
-    IO.print( // Newline here is ignored.
+    System.print( // Newline here is ignored.
         "hi")
 
 In practice, this means you can put each statement on its own line and wrap
@@ -79,16 +79,16 @@ statement for the else:
     :::dart
     if (happy && knowIt) {
       hands.clap
-    } else IO.print("sad")
+    } else System.print("sad")
 
 Blocks have two similar but not identical forms. Typically, blocks contain a
 series of statements like:
 
     :::dart
     {
-      IO.print("one")
-      IO.print("two")
-      IO.print("three")
+      System.print("one")
+      System.print("two")
+      System.print("three")
     }
 
 Blocks of this form when used for method and function bodies automatically

doc/site/template-core.html

@@ -38,7 +38,7 @@
         <li><a href="range.html">Range</a></li>
         <li><a href="sequence.html">Sequence</a></li>
         <li><a href="string.html">String</a></li>
-        <li><a href="io.html">IO</a></li>
+        <li><a href="system.html">System</a></li>
       </ul>
     </section>
   </nav>

doc/site/values.markdown

@@ -57,11 +57,11 @@ A handful of escape characters are supported:
 A `\u` followed by four hex digits can be used to specify a Unicode code point:
 
     :::dart
-    IO.print("\u0041\u0b83\u00DE") // "AஃÞ"
+    System.print("\u0041\u0b83\u00DE") // "AஃÞ"
 
 A `\x` followed by two hex digits specifies a single unencoded byte:
 
-    IO.print("\x48\x69\x2e") // "Hi."
+    System.print("\x48\x69\x2e") // "Hi."
 
 Strings are instances of class [String](core/string.html).
 
@@ -90,7 +90,7 @@ example:
     :::dart
     var list = ["a", "b", "c", "d", "e"]
     var slice = list[1..3]
-    IO.print(slice) // ["b", "c", "d"]
+    System.print(slice) // ["b", "c", "d"]
 
 Their class is [Range](core/range.html).
 

doc/site/variables.markdown

@@ -13,7 +13,7 @@ defined, it can be accessed by name as you would expect.
 
     :::dart
     var animal = "Slow Loris"
-    IO.print(animal) // Prints "Slow Loris".
+    System.print(animal) // Prints "Slow Loris".
 
 ## Scope
 
@@ -22,11 +22,11 @@ until the end of the [block](syntax.html#blocks) where that definition appears.
 
     :::dart
     {
-      IO.print(a) // ERROR! a doesn't exist yet.
+      System.print(a) // ERROR! a doesn't exist yet.
       var a = 123
-      IO.print(a) // "123"
+      System.print(a) // "123"
     }
-    IO.print(a) // ERROR! a doesn't exist anymore.
+    System.print(a) // ERROR! a doesn't exist anymore.
 
 Variables defined at the top level of a script are *top-level* and are visible
 to the [module](modules.html) system. All other variables are *local*.
@@ -38,9 +38,9 @@ intend to do much).
     var a = "outer"
     {
       var a = "inner"
-      IO.print(a) // Prints "inner".
+      System.print(a) // Prints "inner".
     }
-    IO.print(a) // Prints "outer".
+    System.print(a) // Prints "outer".
 
 Declaring a variable with the same name in the *same* scope *is* an error.
 
@@ -65,6 +65,6 @@ assigned value.
 
     :::dart
     var a = "before"
-    IO.print(a = "after") // Prints "after".
+    System.print(a = "after") // Prints "after".
 
 **TODO: Top-level names.**

example/hello.wren

@@ -1 +1 @@
-IO.print("Hello, world!")
+System.print("Hello, world!")

example/import-module/lovecraft.wren

@@ -5,4 +5,4 @@ class Lovecraft {
   say() { Cthulu.new().message }
 }
 
-IO.print(Lovecraft.new().say())
+System.print(Lovecraft.new().say())

example/mandelbrot.wren

@@ -29,8 +29,8 @@ for (yPixel in 0...24) {
       }
     }
 
-    IO.write(pixel)
+    System.write(pixel)
   }
 
-  IO.print("")
-}
+  System.print()
+}

example/sokoban.wren

@@ -1 +0,0 @@
-IO.print("Hello, world!")

example/syntax.wren

@@ -9,7 +9,7 @@ class SyntaxExample {
   // Constructor
   construct new() {
     // Top-level name `IO`
-    IO.print("I am a constructor!")
+    System.print("I am a constructor!")
 
     // Method calls
     variables
@@ -58,7 +58,7 @@ class SyntaxExample {
   field=(value) { _field = value }
 
   // Method with arguments
-  print(a, b) { IO.print(a + b) }
+  print(a, b) { System.print(a + b) }
 
   // Operators
   +(other) { "infix + " + other }
@@ -97,7 +97,7 @@ class ReservedWords is SyntaxExample {
 
     // `for`, `in`
     for (beatle in ["george", "john", "paul", "ringo"]) {
-      IO.print(beatle)
+      System.print(beatle)
       // `break`
       break
     }
@@ -147,9 +147,9 @@ class Literals is SyntaxExample {
     "\t" // Tab.
     "\v" // Vertical tab.
     // Unicode code points
-    IO.print("\u0041fgdg\u0b83\u00DE") // "AஃÞ"
+    System.print("\u0041fgdg\u0b83\u00DE") // "AஃÞ"
     // Unencoded bytes
-    IO.print("\x48\x69\x2e") // "Hi."
+    System.print("\x48\x69\x2e") // "Hi."
   }
 
   ranges {

project/xcode/wren.xcodeproj/project.pbxproj

@@ -17,7 +17,6 @@
 		29205C991AB4E6430073018D /* wren_compiler.c in Sources */ = {isa = PBXBuildFile; fileRef = 29205C921AB4E6430073018D /* wren_compiler.c */; };
 		29205C9A1AB4E6430073018D /* wren_core.c in Sources */ = {isa = PBXBuildFile; fileRef = 29205C931AB4E6430073018D /* wren_core.c */; };
 		29205C9B1AB4E6430073018D /* wren_debug.c in Sources */ = {isa = PBXBuildFile; fileRef = 29205C941AB4E6430073018D /* wren_debug.c */; };
-		29205C9C1AB4E6430073018D /* wren_io.c in Sources */ = {isa = PBXBuildFile; fileRef = 29205C951AB4E6430073018D /* wren_io.c */; };
 		29205C9D1AB4E6430073018D /* wren_utils.c in Sources */ = {isa = PBXBuildFile; fileRef = 29205C961AB4E6430073018D /* wren_utils.c */; };
 		29205C9E1AB4E6430073018D /* wren_value.c in Sources */ = {isa = PBXBuildFile; fileRef = 29205C971AB4E6430073018D /* wren_value.c */; };
 		29205C9F1AB4E6430073018D /* wren_vm.c in Sources */ = {isa = PBXBuildFile; fileRef = 29205C981AB4E6430073018D /* wren_vm.c */; };
@@ -63,7 +62,6 @@
 		29205C921AB4E6430073018D /* wren_compiler.c */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.c; name = wren_compiler.c; path = ../../src/vm/wren_compiler.c; sourceTree = "<group>"; };
 		29205C931AB4E6430073018D /* wren_core.c */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.c; name = wren_core.c; path = ../../src/vm/wren_core.c; sourceTree = "<group>"; };
 		29205C941AB4E6430073018D /* wren_debug.c */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.c; name = wren_debug.c; path = ../../src/vm/wren_debug.c; sourceTree = "<group>"; };
-		29205C951AB4E6430073018D /* wren_io.c */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.c; name = wren_io.c; path = ../../src/vm/wren_io.c; sourceTree = "<group>"; };
 		29205C961AB4E6430073018D /* wren_utils.c */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.c; name = wren_utils.c; path = ../../src/vm/wren_utils.c; sourceTree = "<group>"; };
 		29205C971AB4E6430073018D /* wren_value.c */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.c; name = wren_value.c; path = ../../src/vm/wren_value.c; sourceTree = "<group>"; };
 		29205C981AB4E6430073018D /* wren_vm.c */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.c; name = wren_vm.c; path = ../../src/vm/wren_vm.c; sourceTree = "<group>"; };
@@ -71,7 +69,6 @@
 		29205CA21AB4E65E0073018D /* wren_compiler.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = wren_compiler.h; path = ../../src/vm/wren_compiler.h; sourceTree = "<group>"; };
 		29205CA31AB4E65E0073018D /* wren_core.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = wren_core.h; path = ../../src/vm/wren_core.h; sourceTree = "<group>"; };
 		29205CA41AB4E65E0073018D /* wren_debug.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = wren_debug.h; path = ../../src/vm/wren_debug.h; sourceTree = "<group>"; };
-		29205CA51AB4E65E0073018D /* wren_io.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = wren_io.h; path = ../../src/vm/wren_io.h; sourceTree = "<group>"; };
 		29205CA61AB4E65E0073018D /* wren_utils.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = wren_utils.h; path = ../../src/vm/wren_utils.h; sourceTree = "<group>"; };
 		29205CA71AB4E65E0073018D /* wren_value.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = wren_value.h; path = ../../src/vm/wren_value.h; sourceTree = "<group>"; };
 		29205CA81AB4E65E0073018D /* wren_vm.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = wren_vm.h; path = ../../src/vm/wren_vm.h; sourceTree = "<group>"; };
@@ -137,8 +134,6 @@
 				29205C931AB4E6430073018D /* wren_core.c */,
 				29205CA41AB4E65E0073018D /* wren_debug.h */,
 				29205C941AB4E6430073018D /* wren_debug.c */,
-				29205CA51AB4E65E0073018D /* wren_io.h */,
-				29205C951AB4E6430073018D /* wren_io.c */,
 				29DE39521AC3A50A00987D41 /* wren_meta.h */,
 				29DE39511AC3A50A00987D41 /* wren_meta.c */,
 				296371B31AC713D000079FDA /* wren_opcodes.h */,
@@ -292,7 +287,6 @@
 				29C8A9331AB71FFF00DEC81D /* vm.c in Sources */,
 				291647C41BA5EA45006142EE /* scheduler.c in Sources */,
 				29205C9B1AB4E6430073018D /* wren_debug.c in Sources */,
-				29205C9C1AB4E6430073018D /* wren_io.c in Sources */,
 				29205C9D1AB4E6430073018D /* wren_utils.c in Sources */,
 				29205C9E1AB4E6430073018D /* wren_value.c in Sources */,
 				29205C9F1AB4E6430073018D /* wren_vm.c in Sources */,

script/test.py

@@ -14,7 +14,7 @@ WREN_DIR = dirname(dirname(realpath(__file__)))
 WREN_APP = join(WREN_DIR, 'bin', 'wrend')
 TEST_APP = join(WREN_DIR, 'build', 'debug', 'test', 'wrend')
 
-EXPECT_PATTERN = re.compile(r'// expect: (.*)')
+EXPECT_PATTERN = re.compile(r'// expect: ?(.*)')
 EXPECT_ERROR_PATTERN = re.compile(r'// expect error(?! line)')
 EXPECT_ERROR_LINE_PATTERN = re.compile(r'// expect error line (\d+)')
 EXPECT_RUNTIME_ERROR_PATTERN = re.compile(r'// expect runtime error: (.+)')

src/vm/wren_common.h

@@ -44,13 +44,6 @@
   #endif
 #endif
 
-// If true, loads the "IO" class in the standard library.
-//
-// Defaults to on.
-#ifndef WREN_USE_LIB_IO
-  #define WREN_USE_LIB_IO 1
-#endif
-
 // If true, loads the "Meta" class in the standard library.
 //
 // Defaults to on.

src/vm/wren_core.c

@@ -4,6 +4,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <time.h>
 
 #include "wren_common.h"
 #include "wren_core.h"
@@ -1041,6 +1042,17 @@ DEF_PRIMITIVE(string_toString)
   RETURN_VAL(args[0]);
 }
 
+DEF_PRIMITIVE(system_clock)
+{
+  RETURN_NUM((double)clock() / CLOCKS_PER_SEC);
+}
+
+DEF_PRIMITIVE(system_writeString)
+{
+  printf("%s", AS_CSTRING(args[1]));
+  RETURN_VAL(args[1]);
+}
+
 // Creates either the Object or Class class in the core library with [name].
 static ObjClass* defineClass(WrenVM* vm, ObjModule* module, const char* name)
 {
@@ -1254,6 +1266,10 @@ void wrenInitializeCore(WrenVM* vm)
   PRIMITIVE(vm->rangeClass, "iteratorValue(_)", range_iteratorValue);
   PRIMITIVE(vm->rangeClass, "toString", range_toString);
 
+  ObjClass* systemClass = AS_CLASS(wrenFindVariable(vm, coreModule, "System"));
+  PRIMITIVE(systemClass->obj.classObj, "clock", system_clock);
+  PRIMITIVE(systemClass->obj.classObj, "writeString_(_)", system_writeString);
+  
   // While bootstrapping the core types and running the core library, a number
   // of string objects have been created, many of which were instantiated
   // before stringClass was stored in the VM. Some of them *must* be created

src/vm/wren_core.wren.inc

@@ -214,4 +214,39 @@ static const char* coreModuleSource =
 "  iteratorValue(iterator) { _map.valueIteratorValue_(iterator) }\n"
 "}\n"
 "\n"
-"class Range is Sequence {}\n";
+"class Range is Sequence {}\n"
+"\n"
+"class System {\n"
+"  static print() {\n"
+"    writeString_(\"\n\")\n"
+"  }\n"
+"\n"
+"  static print(obj) {\n"
+"    writeObject_(obj)\n"
+"    writeString_(\"\n\")\n"
+"    return obj\n"
+"  }\n"
+"\n"
+"  static printAll(sequence) {\n"
+"    for (object in sequence) writeObject_(object)\n"
+"    writeString_(\"\n\")\n"
+"  }\n"
+"\n"
+"  static write(obj) {\n"
+"    writeObject_(obj)\n"
+"    return obj\n"
+"  }\n"
+"\n"
+"  static writeAll(sequence) {\n"
+"    for (object in sequence) writeObject_(object)\n"
+"  }\n"
+"\n"
+"  static writeObject_(obj) {\n"
+"    var string = obj.toString\n"
+"    if (string is String) {\n"
+"      writeString_(string)\n"
+"    } else {\n"
+"      writeString_(\"[invalid toString]\")\n"
+"    }\n"
+"  }\n"
+"}\n";

src/vm/wren_io.c

@@ -1,59 +0,0 @@
-#include "wren_io.h"
-
-#if WREN_USE_LIB_IO
-
-#include <stdio.h>
-#include <string.h>
-#include <time.h>
-
-// TODO: This is an arbitrary limit. Do something smarter.
-#define MAX_READ_LEN 1024
-
-#include "wren_io.wren.inc"
-
-static void ioWriteString(WrenVM* vm)
-{
-  const char* s = wrenGetArgumentString(vm, 1);
-  // TODO: Check for null.
-  printf("%s", s);
-}
-
-static void ioRead(WrenVM* vm)
-{
-  char buffer[MAX_READ_LEN];
-  char* result = fgets(buffer, MAX_READ_LEN, stdin);
-
-  if (result != NULL)
-  {
-    wrenReturnString(vm, buffer, (int)strlen(buffer));
-  }
-}
-
-static void ioClock(WrenVM* vm)
-{
-  wrenReturnDouble(vm, (double)clock() / CLOCKS_PER_SEC);
-}
-
-static void ioTime(WrenVM* vm)
-{
-  wrenReturnDouble(vm, (double)time(NULL));
-}
-
-void wrenLoadIOLibrary(WrenVM* vm)
-{
-  wrenInterpret(vm, "", ioModuleSource);
-}
-
-WrenForeignMethodFn wrenBindIOForeignMethod(WrenVM* vm, const char* className,
-                                            const char* signature)
-{
-  if (strcmp(className, "IO") != 0) return NULL;
-
-  if (strcmp(signature, "writeString_(_)") == 0) return ioWriteString;
-  if (strcmp(signature, "clock") == 0) return ioClock;
-  if (strcmp(signature, "time") == 0) return ioTime;
-  if (strcmp(signature, "read()") == 0) return ioRead;
-  return NULL;
-}
-
-#endif

src/vm/wren_io.h

@@ -1,18 +0,0 @@
-#ifndef wren_io_h
-#define wren_io_h
-
-#include "wren.h"
-#include "wren_common.h"
-
-// This module defines the IO class and its associated methods. They are
-// implemented using the C standard library.
-#if WREN_USE_LIB_IO
-
-void wrenLoadIOLibrary(WrenVM* vm);
-
-WrenForeignMethodFn wrenBindIOForeignMethod(WrenVM* vm, const char* className,
-                                            const char* signature);
-
-#endif
-
-#endif

src/vm/wren_io.wren.inc

@@ -1,103 +0,0 @@
-// Generated automatically from builtin/io.wren. Do not edit.
-static const char* ioModuleSource =
-"class IO {\n"
-"  static print {\n"
-"    writeString_(\"\n\")\n"
-"  }\n"
-"\n"
-"  static print(obj) {\n"
-"    writeObject_(obj)\n"
-"    writeString_(\"\n\")\n"
-"    return obj\n"
-"  }\n"
-"\n"
-"  static print(a1, a2) {\n"
-"    printAll([a1, a2])\n"
-"  }\n"
-"\n"
-"  static print(a1, a2, a3) {\n"
-"    printAll([a1, a2, a3])\n"
-"  }\n"
-"\n"
-"  static print(a1, a2, a3, a4) {\n"
-"    printAll([a1, a2, a3, a4])\n"
-"  }\n"
-"\n"
-"  static print(a1, a2, a3, a4, a5) {\n"
-"    printAll([a1, a2, a3, a4, a5])\n"
-"  }\n"
-"\n"
-"  static print(a1, a2, a3, a4, a5, a6) {\n"
-"    printAll([a1, a2, a3, a4, a5, a6])\n"
-"  }\n"
-"\n"
-"  static print(a1, a2, a3, a4, a5, a6, a7) {\n"
-"    printAll([a1, a2, a3, a4, a5, a6, a7])\n"
-"  }\n"
-"\n"
-"  static print(a1, a2, a3, a4, a5, a6, a7, a8) {\n"
-"    printAll([a1, a2, a3, a4, a5, a6, a7, a8])\n"
-"  }\n"
-"\n"
-"  static print(a1, a2, a3, a4, a5, a6, a7, a8, a9) {\n"
-"    printAll([a1, a2, a3, a4, a5, a6, a7, a8, a9])\n"
-"  }\n"
-"\n"
-"  static print(a1, a2, a3, a4, a5, a6, a7, a8, a9, a10) {\n"
-"    printAll([a1, a2, a3, a4, a5, a6, a7, a8, a9, a10])\n"
-"  }\n"
-"\n"
-"  static print(a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11) {\n"
-"    printAll([a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11])\n"
-"  }\n"
-"\n"
-"  static print(a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12) {\n"
-"    printAll([a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12])\n"
-"  }\n"
-"\n"
-"  static print(a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13) {\n"
-"    printAll([a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13])\n"
-"  }\n"
-"\n"
-"  static print(a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14) {\n"
-"    printAll([a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14])\n"
-"  }\n"
-"\n"
-"  static print(a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14, a15) {\n"
-"    printAll([a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14, a15])\n"
-"  }\n"
-"\n"
-"  static print(a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14, a15, a16) {\n"
-"    printAll([a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14, a15, a16])\n"
-"  }\n"
-"\n"
-"  static printAll(sequence) {\n"
-"    for (object in sequence) writeObject_(object)\n"
-"    writeString_(\"\n\")\n"
-"  }\n"
-"\n"
-"  static write(obj) {\n"
-"    writeObject_(obj)\n"
-"    return obj\n"
-"  }\n"
-"\n"
-"  static read(prompt) {\n"
-"    if (!(prompt is String)) Fiber.abort(\"Prompt must be a string.\")\n"
-"    write(prompt)\n"
-"    return read()\n"
-"  }\n"
-"\n"
-"  static writeObject_(obj) {\n"
-"    var string = obj.toString\n"
-"    if (string is String) {\n"
-"      writeString_(string)\n"
-"    } else {\n"
-"      writeString_(\"[invalid toString]\")\n"
-"    }\n"
-"  }\n"
-"\n"
-"  foreign static writeString_(string)\n"
-"  foreign static clock\n"
-"  foreign static time\n"
-"  foreign static read()\n"
-"}\n";

src/vm/wren_vm.c

@@ -298,20 +298,6 @@ static WrenForeignMethodFn findForeignMethod(WrenVM* vm,
                                              bool isStatic,
                                              const char* signature)
 {
-  WrenForeignMethodFn fn;
-
-  // Bind foreign methods in the core module.
-  if (strcmp(moduleName, "core") == 0)
-  {
-    #if WREN_USE_LIB_IO
-    fn = wrenBindIOForeignMethod(vm, className, signature);
-    #endif
-    
-    ASSERT(fn != NULL, "Failed to bind core module foreign method.");
-    return fn;
-  }
-
-  // For other modules, let the host bind it.
   if (vm->bindForeignMethod == NULL) return NULL;
 
   return vm->bindForeignMethod(vm, moduleName, className, isStatic, signature);

test/README.md

@@ -8,9 +8,6 @@ This contains the automated validation suite for the VM and built-in libraries.
   classes. If a bug is in `wren_core.c` or `wren_value.c`, it will most likely
   break one of these tests.
 
-* `io/` - Tests for the built in IO library. In other words, methods on the
-  `IO` class. If a bug is in `wren_io.c`, it should break one of these tests.
-
 * `language/` - Tests of the language itself, its grammar and runtime
   semantics. If a bug is in `wren_compiler.c` or `wren_vm.c`, it will most
   likely break one of these tests. This includes tests for the syntax for the

test/api/foreign_class.wren

@@ -11,27 +11,27 @@ foreign class Counter {
 }
 
 var counter = Counter.new()
-IO.print(counter.value) // expect: 0
+System.print(counter.value) // expect: 0
 counter.increment(3.1)
-IO.print(counter.value) // expect: 3.1
+System.print(counter.value) // expect: 3.1
 counter.increment(1.2)
-IO.print(counter.value) // expect: 4.3
+System.print(counter.value) // expect: 4.3
 
 // Foreign classes can inherit a class as long as it has no fields.
 class PointBase {
   inherited() {
-    IO.print("inherited method")
+    System.print("inherited method")
   }
 }
 
 // Class with non-default constructor.
 foreign class Point is PointBase {
   construct new() {
-    IO.print("default")
+    System.print("default")
   }
 
   construct new(x, y, z) {
-    IO.print(x, ", ", y, ", ", z)
+    System.print(x.toString + ", " + y.toString + ", " + z.toString)
   }
 
   foreign translate(x, y, z)
@@ -39,19 +39,19 @@ foreign class Point is PointBase {
 }
 
 var p = Point.new(1, 2, 3) // expect: 1, 2, 3
-IO.print(p) // expect: (1, 2, 3)
+System.print(p) // expect: (1, 2, 3)
 p.translate(3, 4, 5)
-IO.print(p) // expect: (4, 6, 8)
+System.print(p) // expect: (4, 6, 8)
 
 p = Point.new() // expect: default
-IO.print(p) // expect: (0, 0, 0)
+System.print(p) // expect: (0, 0, 0)
 
 p.inherited() // expect: inherited method
 
 var error = Fiber.new {
   class Subclass is Point {}
 }.try()
-IO.print(error) // expect: Class 'Subclass' cannot inherit from foreign class 'Point'.
+System.print(error) // expect: Class 'Subclass' cannot inherit from foreign class 'Point'.
 
 // Class with a finalizer.
 foreign class Resource {
@@ -65,14 +65,14 @@ var resources = [
 ]
 
 Api.gc()
-IO.print(Api.finalized) // expect: 0
+System.print(Api.finalized) // expect: 0
 
 resources.removeAt(-1)
 
 Api.gc()
-IO.print(Api.finalized) // expect: 1
+System.print(Api.finalized) // expect: 1
 
 resources.clear()
 
 Api.gc()
-IO.print(Api.finalized) // expect: 3
+System.print(Api.finalized) // expect: 3

test/api/returns.wren

@@ -8,10 +8,10 @@ class Api {
   foreign static returnFalse
 }
 
-IO.print(Api.implicitNull == null) // expect: true
+System.print(Api.implicitNull == null) // expect: true
 
-IO.print(Api.returnInt)  // expect: 123456
-IO.print(Api.returnFloat) // expect: 123.456
+System.print(Api.returnInt)  // expect: 123456
+System.print(Api.returnFloat) // expect: 123.456
 
-IO.print(Api.returnTrue)  // expect: true
-IO.print(Api.returnFalse) // expect: false
+System.print(Api.returnTrue)  // expect: true
+System.print(Api.returnFalse) // expect: false

test/api/value.wren

@@ -11,4 +11,4 @@ for (i in 1...10) {
   s = s + " more"
 }
 
-IO.print(Api.value) // expect: [list, of, strings]
+System.print(Api.value) // expect: [list, of, strings]

test/benchmark/binary_trees.wren

@@ -24,10 +24,10 @@ var minDepth = 4
 var maxDepth = 12
 var stretchDepth = maxDepth + 1
 
-var start = IO.clock
+var start = System.clock
 
-IO.print("stretch tree of depth ", stretchDepth, " check: ",
-    Tree.new(0, stretchDepth).check)
+System.print("stretch tree of depth " + stretchDepth.toString + " check: " +
+    Tree.new(0, stretchDepth).check.toString)
 
 var longLivedTree = Tree.new(0, maxDepth)
 
@@ -44,10 +44,12 @@ while (depth < stretchDepth) {
     check = check + Tree.new(i, depth).check + Tree.new(-i, depth).check
   }
 
-  IO.print((iterations * 2), " trees of depth ", depth, " check: ", check)
+  System.print((iterations * 2).toString + " trees of depth " +
+      depth.toString + " check: " + check.toString)
   iterations = iterations / 4
   depth = depth + 2
 }
 
-IO.print("long lived tree of depth ", maxDepth, " check: ", longLivedTree.check)
-IO.print("elapsed: ", (IO.clock - start))
+System.print("long lived tree of depth " + maxDepth.toString + " check: " +
+    longLivedTree.check.toString)
+System.print("elapsed: " + (System.clock - start).toString)

test/benchmark/delta_blue.wren

@@ -92,7 +92,7 @@ class Constraint {
     chooseMethod(mark)
     if (!isSatisfied) {
       if (_strength == REQUIRED) {
-        IO.print("Could not satisfy a required constraint!")
+        System.print("Could not satisfy a required constraint!")
       }
       return null
     }
@@ -102,7 +102,7 @@ class Constraint {
     var overridden = out.determinedBy
     if (overridden != null) overridden.markUnsatisfied
     out.determinedBy = this
-    if (!ThePlanner.addPropagate(this, mark)) IO.print("Cycle encountered")
+    if (!ThePlanner.addPropagate(this, mark)) System.print("Cycle encountered")
     out.mark = mark
     return overridden
   }
@@ -669,31 +669,31 @@ var projectionTest = Fn.new {|n|
 
   change.call(src, 17)
   total = total + dst.value
-  if (dst.value != 1170) IO.print("Projection 1 failed")
+  if (dst.value != 1170) System.print("Projection 1 failed")
 
   change.call(dst, 1050)
 
   total = total + src.value
-  if (src.value != 5) IO.print("Projection 2 failed")
+  if (src.value != 5) System.print("Projection 2 failed")
 
   change.call(scale, 5)
   for (i in 0...n - 1) {
     total = total + dests[i].value
-    if (dests[i].value != i * 5 + 1000) IO.print("Projection 3 failed")
+    if (dests[i].value != i * 5 + 1000) System.print("Projection 3 failed")
   }
 
   change.call(offset, 2000)
   for (i in 0...n - 1) {
     total = total + dests[i].value
-    if (dests[i].value != i * 5 + 2000) IO.print("Projection 4 failed")
+    if (dests[i].value != i * 5 + 2000) System.print("Projection 4 failed")
   }
 }
 
-var start = IO.clock
+var start = System.clock
 for (i in 0...40) {
   chainTest.call(100)
   projectionTest.call(100)
 }
 
-IO.print(total)
-IO.print("elapsed: ", IO.clock - start)
+System.print(total)
+System.print("elapsed: " + (System.clock - start).toString)

test/benchmark/fib.wren

@@ -5,8 +5,8 @@ class Fib {
   }
 }
 
-var start = IO.clock
+var start = System.clock
 for (i in 1..5) {
-  IO.print(Fib.get(28))
+  System.print(Fib.get(28))
 }
-IO.print("elapsed: ", IO.clock - start)
+System.print("elapsed: " + (System.clock - start).toString)

test/benchmark/fibers.wren

@@ -2,7 +2,7 @@
 var fibers = []
 var sum = 0
 
-var start = IO.clock
+var start = System.clock
 
 for (i in 0...100000) {
   fibers.add(Fiber.new {
@@ -12,5 +12,5 @@ for (i in 0...100000) {
 }
 
 fibers[0].call()
-IO.print(sum)
-IO.print("elapsed: ", IO.clock - start)
+System.print(sum)
+System.print("elapsed: " + (System.clock - start).toString)

test/benchmark/for.wren

@@ -1,10 +1,10 @@
 var list = []
 
-var start = IO.clock
+var start = System.clock
 for (i in 0...1000000) list.add(i)
 
 var sum = 0
 for (i in list) sum = sum + i
 
-IO.print(sum)
-IO.print("elapsed: ", IO.clock - start)
+System.print(sum)
+System.print("elapsed: " + (System.clock - start).toString)

test/benchmark/map_numeric.wren

@@ -1,4 +1,4 @@
-var start = IO.clock
+var start = System.clock
 
 var map = {}
 
@@ -10,10 +10,10 @@ var sum = 0
 for (i in 1..1000000) {
   sum = sum + map[i]
 }
-IO.print(sum)
+System.print(sum)
 
 for (i in 1..1000000) {
   map.remove(i)
 }
 
-IO.print("elapsed: ", IO.clock - start)
+System.print("elapsed: " + (System.clock - start).toString)

test/benchmark/map_string.wren

@@ -77,7 +77,7 @@ for (animal in animals) {
   }
 }
 
-var start = IO.clock
+var start = System.clock
 
 var map = {}
 
@@ -96,5 +96,5 @@ for (key in keys) {
   map.remove(key)
 }
 
-IO.print(sum)
-IO.print("elapsed: ", IO.clock - start)
+System.print(sum)
+System.print("elapsed: " + (System.clock - start).toString)

test/benchmark/method_call.wren

@@ -28,7 +28,7 @@ class NthToggle is Toggle {
   }
 }
 
-var start = IO.clock
+var start = System.clock
 var n = 100000
 var val = true
 var toggle = Toggle.new(val)
@@ -46,7 +46,7 @@ for (i in 0...n) {
   val = toggle.activate.value
 }
 
-IO.print(toggle.value)
+System.print(toggle.value)
 
 val = true
 var ntoggle = NthToggle.new(val, 3)
@@ -64,5 +64,5 @@ for (i in 0...n) {
   val = ntoggle.activate.value
 }
 
-IO.print(ntoggle.value)
-IO.print("elapsed: ", IO.clock - start)
+System.print(ntoggle.value)
+System.print("elapsed: " + (System.clock - start).toString)

test/benchmark/string_equals.wren

@@ -1,4 +1,4 @@
-var start = IO.clock
+var start = System.clock
 
 var count = 0
 for (i in 1..1000000) {
@@ -20,5 +20,5 @@ for (i in 1..1000000) {
       "another") count = count + 1
 }
 
-IO.print(count)
-IO.print("elapsed: ", IO.clock - start)
+System.print(count)
+System.print("elapsed: " + (System.clock - start).toString)

test/core/bool/equality.wren

@@ -1,23 +1,23 @@
-IO.print(true == true)    // expect: true
-IO.print(true == false)   // expect: false
-IO.print(false == true)   // expect: false
-IO.print(false == false)  // expect: true
+System.print(true == true)    // expect: true
+System.print(true == false)   // expect: false
+System.print(false == true)   // expect: false
+System.print(false == false)  // expect: true
 
 // Not equal to other types.
-IO.print(true == 1)        // expect: false
-IO.print(false == 0)       // expect: false
-IO.print(true == "true")   // expect: false
-IO.print(false == "false") // expect: false
-IO.print(false == "")      // expect: false
+System.print(true == 1)        // expect: false
+System.print(false == 0)       // expect: false
+System.print(true == "true")   // expect: false
+System.print(false == "false") // expect: false
+System.print(false == "")      // expect: false
 
-IO.print(true != true)    // expect: false
-IO.print(true != false)   // expect: true
-IO.print(false != true)   // expect: true
-IO.print(false != false)  // expect: false
+System.print(true != true)    // expect: false
+System.print(true != false)   // expect: true
+System.print(false != true)   // expect: true
+System.print(false != false)  // expect: false
 
 // Not equal to other types.
-IO.print(true != 1)        // expect: true
-IO.print(false != 0)       // expect: true
-IO.print(true != "true")   // expect: true
-IO.print(false != "false") // expect: true
-IO.print(false != "")      // expect: true
+System.print(true != 1)        // expect: true
+System.print(false != 0)       // expect: true
+System.print(true != "true")   // expect: true
+System.print(false != "false") // expect: true
+System.print(false != "")      // expect: true

test/core/bool/not.wren

@@ -1,3 +1,3 @@
-IO.print(!true)    // expect: false
-IO.print(!false)   // expect: true
-IO.print(!!true)   // expect: true
+System.print(!true)    // expect: false
+System.print(!false)   // expect: true
+System.print(!!true)   // expect: true

test/core/bool/to_string.wren

@@ -1,2 +1,2 @@
-IO.print(true.toString)  // expect: true
-IO.print(false.toString) // expect: false
+System.print(true.toString)  // expect: true
+System.print(false.toString) // expect: false

test/core/bool/type.wren

@@ -1,4 +1,4 @@
-IO.print(true is Bool)      // expect: true
-IO.print(true is Object)    // expect: true
-IO.print(true is Num)       // expect: false
-IO.print(true.type == Bool) // expect: true
+System.print(true is Bool)      // expect: true
+System.print(true is Object)    // expect: true
+System.print(true is Num)       // expect: false
+System.print(true.type == Bool) // expect: true

test/core/class/equality.wren

@@ -1,13 +1,13 @@
-IO.print(Num == Num)  // expect: true
-IO.print(Num == Bool) // expect: false
+System.print(Num == Num)  // expect: true
+System.print(Num == Bool) // expect: false
 
 // Not equal to other types.
-IO.print(Num == 123)  // expect: false
-IO.print(Num == true) // expect: false
+System.print(Num == 123)  // expect: false
+System.print(Num == true) // expect: false
 
-IO.print(Num != Num)  // expect: false
-IO.print(Num != Bool) // expect: true
+System.print(Num != Num)  // expect: false
+System.print(Num != Bool) // expect: true
 
 // Not equal to other types.
-IO.print(Num != 123)  // expect: true
-IO.print(Num != true) // expect: true
+System.print(Num != 123)  // expect: true
+System.print(Num != true) // expect: true

test/core/class/name.wren

@@ -1,13 +1,13 @@
 class Foo {}
 
-IO.print(Foo.name) // expect: Foo
-IO.print(Foo.type.name) // expect: Foo metaclass
+System.print(Foo.name) // expect: Foo
+System.print(Foo.type.name) // expect: Foo metaclass
 
 // Make sure the built-in classes have proper names too.
-IO.print(Object.name) // expect: Object
-IO.print(Bool.name) // expect: Bool
-IO.print(Class.name) // expect: Class
+System.print(Object.name) // expect: Object
+System.print(Bool.name) // expect: Bool
+System.print(Class.name) // expect: Class
 
 // And metaclass names.
-IO.print(Object.type.name) // expect: Object metaclass
-IO.print(Bool.type.name) // expect: Bool metaclass
+System.print(Object.type.name) // expect: Object metaclass
+System.print(Bool.type.name) // expect: Bool metaclass

test/core/class/supertype.wren

@@ -5,11 +5,11 @@ class Bar is Foo {}
 class Baz is Bar {}
 
 // A class with no explicit superclass inherits Object.
-IO.print(Foo.supertype == Object) // expect: true
+System.print(Foo.supertype == Object) // expect: true
 
 // Otherwise, it's the superclass.
-IO.print(Bar.supertype == Foo) // expect: true
-IO.print(Baz.supertype == Bar) // expect: true
+System.print(Bar.supertype == Foo) // expect: true
+System.print(Baz.supertype == Bar) // expect: true
 
 // Object has no supertype.
-IO.print(Object.supertype) // expect: null
+System.print(Object.supertype) // expect: null

test/core/class/type.wren

@@ -1,15 +1,15 @@
 class Foo {}
 
 // A class is a class.
-IO.print(Foo is Class) // expect: true
+System.print(Foo is Class) // expect: true
 
 // Its metatype is also a class.
-IO.print(Foo.type is Class) // expect: true
+System.print(Foo.type is Class) // expect: true
 
 // The metatype's metatype is Class.
-IO.print(Foo.type.type == Class) // expect: true
+System.print(Foo.type.type == Class) // expect: true
 
 // And Class's metatype circles back onto itself.
-IO.print(Foo.type.type.type == Class) // expect: true
-IO.print(Foo.type.type.type.type == Class) // expect: true
-IO.print(Foo.type.type.type.type.type == Class) // expect: true
+System.print(Foo.type.type.type == Class) // expect: true
+System.print(Foo.type.type.type.type == Class) // expect: true
+System.print(Foo.type.type.type.type.type == Class) // expect: true

test/core/fiber/abort.wren

@@ -2,6 +2,6 @@ var fiber = Fiber.new {
   Fiber.abort("Error message.")
 }
 
-IO.print(fiber.try()) // expect: Error message.
-IO.print(fiber.isDone) // expect: true
-IO.print(fiber.error) // expect: Error message.
+System.print(fiber.try()) // expect: Error message.
+System.print(fiber.isDone) // expect: true
+System.print(fiber.error) // expect: Error message.

test/core/fiber/call.wren

@@ -1,7 +1,7 @@
 var fiber = Fiber.new {
-  IO.print("fiber")
+  System.print("fiber")
 }
 
-IO.print("before") // expect: before
+System.print("before") // expect: before
 fiber.call()       // expect: fiber
-IO.print("after")  // expect: after
+System.print("after")  // expect: after

test/core/fiber/call_done.wren

@@ -1,5 +1,5 @@
 var fiber = Fiber.new {
-  IO.print("call")
+  System.print("call")
 }
 
 fiber.call() // expect: call

test/core/fiber/call_error.wren

@@ -1,6 +1,6 @@
 var fiber = Fiber.new {
   Fiber.abort("Error!")
-  IO.print("should not get here")
+  System.print("should not get here")
 }
 
 fiber.try()

test/core/fiber/call_return_implicit_null.wren

@@ -1,5 +1,5 @@
 var fiber = Fiber.new {
-  IO.print("fiber") // expect: fiber
+  System.print("fiber") // expect: fiber
 }
 
-IO.print(fiber.call()) // expect: null
+System.print(fiber.call()) // expect: null

test/core/fiber/call_return_value.wren

@@ -1,6 +1,6 @@
 var fiber = Fiber.new {
-  IO.print("fiber")
+  System.print("fiber")
   return "result" // expect: fiber
 }
 
-IO.print(fiber.call()) // expect: result
+System.print(fiber.call()) // expect: result

test/core/fiber/call_transferred.wren

@@ -1,12 +1,12 @@
 var main = Fiber.current
 
 var fiber = Fiber.new {
-  IO.print("transferred")
-  IO.print(main.transfer())
-  IO.print("called")
+  System.print("transferred")
+  System.print(main.transfer())
+  System.print("called")
 }
 
 fiber.transfer() // expect: transferred
-IO.print("main") // expect: main
+System.print("main") // expect: main
 fiber.call()     // expect: null
                  // expect: called

test/core/fiber/call_with_value.wren

@@ -1,9 +1,9 @@
 var fiber = Fiber.new {
-  IO.print("fiber")
+  System.print("fiber")
 }
 
 // The first value passed to the fiber is ignored, since there's no yield call
 // to return it.
-IO.print("before")    // expect: before
+System.print("before")    // expect: before
 fiber.call("ignored") // expect: fiber
-IO.print("after")     // expect: after
+System.print("after")     // expect: after

test/core/fiber/call_with_value_done.wren

@@ -1,5 +1,5 @@
 var fiber = Fiber.new {
-  IO.print("call")
+  System.print("call")
 }
 
 fiber.call(1) // expect: call

test/core/fiber/call_with_value_error.wren

@@ -1,6 +1,6 @@
 var fiber = Fiber.new {
   Fiber.abort("Error!")
-  IO.print("should not get here")
+  System.print("should not get here")
 }
 
 fiber.try()

test/core/fiber/call_with_value_transferred.wren

@@ -1,12 +1,12 @@
 var main = Fiber.current
 
 var fiber = Fiber.new {
-  IO.print("transferred")
-  IO.print(main.transfer())
-  IO.print("called")
+  System.print("transferred")
+  System.print(main.transfer())
+  System.print("called")
 }
 
 fiber.transfer()    // expect: transferred
-IO.print("main")    // expect: main
+System.print("main")    // expect: main
 fiber.call("value") // expect: value
                     // expect: called

test/core/fiber/error.wren

@@ -2,6 +2,6 @@ var fiber = Fiber.new {
   "s".unknown
 }
 
-IO.print(fiber.error) // expect: null
-IO.print(fiber.try()) // expect: String does not implement 'unknown'.
-IO.print(fiber.error) // expect: String does not implement 'unknown'.
+System.print(fiber.error) // expect: null
+System.print(fiber.try()) // expect: String does not implement 'unknown'.
+System.print(fiber.error) // expect: String does not implement 'unknown'.

test/core/fiber/is_done.wren

@@ -1,11 +1,11 @@
 var fiber = Fiber.new {
-  IO.print("1")
+  System.print("1")
   Fiber.yield()
-  IO.print("2")
+  System.print("2")
 }
 
-IO.print(fiber.isDone)  // expect: false
+System.print(fiber.isDone)  // expect: false
 fiber.call()            // expect: 1
-IO.print(fiber.isDone)  // expect: false
+System.print(fiber.isDone)  // expect: false
 fiber.call()            // expect: 2
-IO.print(fiber.isDone)  // expect: true
+System.print(fiber.isDone)  // expect: true

test/core/fiber/is_done_after_error.wren

@@ -3,4 +3,4 @@ var fiber = Fiber.new {
 }
 
 fiber.try()
-IO.print(fiber.isDone) // expect: true
+System.print(fiber.isDone) // expect: true

test/core/fiber/resume_caller.wren

@@ -1,16 +1,16 @@
 var b = Fiber.new {
-  IO.print("fiber b")
+  System.print("fiber b")
 }
 
 var a = Fiber.new {
-  IO.print("begin fiber a")
+  System.print("begin fiber a")
   b.call()
-  IO.print("end fiber a")
+  System.print("end fiber a")
 }
 
-IO.print("begin main")
+System.print("begin main")
 a.call()
-IO.print("end main")
+System.print("end main")
 
 // expect: begin main
 // expect: begin fiber a

test/core/fiber/transfer.wren

@@ -1,20 +1,20 @@
 var a = Fiber.new {
-  IO.print("a")
+  System.print("a")
 }
 
 var b = Fiber.new {
-  IO.print("b before")
+  System.print("b before")
   a.transfer()
-  IO.print("b after")
+  System.print("b after")
 }
 
 var c = Fiber.new {
-  IO.print("c before")
+  System.print("c before")
   b.transfer()
-  IO.print("c after")
+  System.print("c after")
 }
 
-IO.print("start") // expect: start
+System.print("start") // expect: start
 
 c.transfer()
 // expect: c before

test/core/fiber/transfer_direct_reenter.wren

@@ -1,9 +1,9 @@
 var F = Fiber.new {
-  IO.print(1)            // expect: 1
-  IO.print(F.transfer()) // expect: null
-  IO.print(2)            // expect: 2
+  System.print(1)            // expect: 1
+  System.print(F.transfer()) // expect: null
+  System.print(2)            // expect: 2
 }
 
 F.call()
 // F remembers its original caller so transfers back to main.
-IO.print(3) // expect: 3
+System.print(3) // expect: 3

test/core/fiber/transfer_indirect_reenter.wren

@@ -1,13 +1,13 @@
 var A = Fiber.new {
-  IO.print(2)
+  System.print(2)
   B.transfer()
-  IO.print("nope")
+  System.print("nope")
 }
 
 var B = Fiber.new {
-  IO.print(1)
+  System.print(1)
   A.transfer()
-  IO.print(3)
+  System.print(3)
 }
 
 B.call()
@@ -15,4 +15,4 @@ B.call()
 // expect: 2
 // expect: 3
 // B remembers its original caller so returns to main.
-IO.print(4) // expect: 4
+System.print(4) // expect: 4

test/core/fiber/transfer_return_call_value.wren

@@ -1,23 +1,23 @@
 var main = Fiber.current
 
 var fiber = Fiber.new {
-  IO.print("fiber 1")
-  IO.print(main.transfer())
+  System.print("fiber 1")
+  System.print(main.transfer())
 
   // Yield to bounce back to main and clear the caller so we don't get a
   // double call() error below.
   Fiber.yield()
 
-  IO.print(main.transfer())
+  System.print(main.transfer())
 }
 
 fiber.transfer() // expect: fiber 1
-IO.print("main 1") // expect: main 1
+System.print("main 1") // expect: main 1
 fiber.call("call 1") // expect: call 1
 
-IO.print("main 2") // expect: main 2
+System.print("main 2") // expect: main 2
 // Transfer back into the fiber so it has a NULL caller.
 fiber.transfer()
 
 fiber.call() // expect: null
-IO.print("main 3") // expect: main 3
+System.print("main 3") // expect: main 3

test/core/fiber/transfer_return_transfer_value.wren

@@ -1,13 +1,13 @@
 var main = Fiber.current
 
 var fiber = Fiber.new {
-  IO.print("fiber")
-  IO.print(main.transfer())
+  System.print("fiber")
+  System.print(main.transfer())
 }
 
 fiber.transfer() // expect: fiber
-IO.print("main") // expect: main
+System.print("main") // expect: main
 fiber.transfer("transfer") // expect: transfer
 
 // This does not get run since we exit when the transferred fiber completes.
-IO.print("nope")
+System.print("nope")

test/core/fiber/transfer_to_done.wren

@@ -1,5 +1,5 @@
 var a = Fiber.new {
-  IO.print("run")
+  System.print("run")
 }
 
 a.call() // expect: run

test/core/fiber/transfer_to_error.wren

@@ -1,6 +1,6 @@
 var a = Fiber.new {
   Fiber.abort("Error!")
-  IO.print("should not get here")
+  System.print("should not get here")
 }
 
 a.try()

test/core/fiber/transfer_to_yielded.wren

@@ -1,7 +1,7 @@
 var fiber = Fiber.new {
-  IO.print("called")
-  IO.print(Fiber.yield())
-  IO.print("transferred")
+  System.print("called")
+  System.print(Fiber.yield())
+  System.print("transferred")
 }
 
 fiber.call()     // expect: called

test/core/fiber/transfer_with_value.wren

@@ -1,20 +1,20 @@
 var a = Fiber.new {
-  IO.print("a")
+  System.print("a")
 }
 
 var b = Fiber.new {
-  IO.print("b before")
+  System.print("b before")
   a.transfer("ignored")
-  IO.print("b after")
+  System.print("b after")
 }
 
 var c = Fiber.new {
-  IO.print("c before")
+  System.print("c before")
   b.transfer("ignored")
-  IO.print("c after")
+  System.print("c after")
 }
 
-IO.print("start") // expect: start
+System.print("start") // expect: start
 
 c.transfer("ignored")
 // expect: c before

test/core/fiber/transfer_with_value_direct_reenter.wren

@@ -1,8 +1,8 @@
 var F = Fiber.new {
-  IO.print(1) // expect: 1
-  IO.print(F.transfer("value")) // expect: value
-  IO.print(2) // expect: 2
+  System.print(1) // expect: 1
+  System.print(F.transfer("value")) // expect: value
+  System.print(2) // expect: 2
 }
 
 F.call()
-IO.print(3) // expect: 3
+System.print(3) // expect: 3

test/core/fiber/transfer_with_value_indirect_reenter.wren

@@ -1,17 +1,17 @@
 var A = Fiber.new {
-  IO.print(2)
+  System.print(2)
   B.transfer("ignored")
-  IO.print("nope")
+  System.print("nope")
 }
 
 var B = Fiber.new {
-  IO.print(1)
+  System.print(1)
   A.transfer("ignored")
-  IO.print(3)
+  System.print(3)
 }
 
 B.call()
 // expect: 1
 // expect: 2
 // expect: 3
-IO.print(4) // expect: 4
+System.print(4) // expect: 4

test/core/fiber/transfer_with_value_to_done.wren

@@ -1,5 +1,5 @@
 var a = Fiber.new {
-  IO.print("run")
+  System.print("run")
 }
 
 a.call() // expect: run

test/core/fiber/transfer_with_value_to_error.wren

@@ -1,6 +1,6 @@
 var a = Fiber.new {
   Fiber.abort("Error!")
-  IO.print("should not get here")
+  System.print("should not get here")
 }
 
 a.try()

test/core/fiber/transfer_with_value_to_yielded.wren

@@ -1,7 +1,7 @@
 var fiber = Fiber.new {
-  IO.print("called")
-  IO.print(Fiber.yield())
-  IO.print("transferred")
+  System.print("called")
+  System.print(Fiber.yield())
+  System.print("transferred")
 }
 
 fiber.call()            // expect: called

test/core/fiber/try.wren

@@ -1,10 +1,10 @@
 var fiber = Fiber.new {
-  IO.print("before")
+  System.print("before")
   true.unknownMethod
-  IO.print("after")
+  System.print("after")
 }
 
-IO.print(fiber.try())
+System.print(fiber.try())
 // expect: before
 // expect: Bool does not implement 'unknownMethod'.
-IO.print("after try") // expect: after try
+System.print("after try") // expect: after try

test/core/fiber/try_when_done.wren

@@ -1,5 +1,5 @@
 var fiber = Fiber.new {
-  IO.print("try")
+  System.print("try")
 }
 
 fiber.try() // expect: try

test/core/fiber/try_without_error.wren

@@ -1,8 +1,8 @@
 var fiber = Fiber.new {
-  IO.print("fiber")
+  System.print("fiber")
 }
 
-IO.print("before")    // expect: before
-IO.print(fiber.try()) // expect: fiber
+System.print("before")    // expect: before
+System.print(fiber.try()) // expect: fiber
                       // expect: null
-IO.print("after")     // expect: after
+System.print("after")     // expect: after

test/core/fiber/type.wren

@@ -1,5 +1,5 @@
 var fiber = Fiber.new {}
-IO.print(fiber is Fiber)      // expect: true
-IO.print(fiber is Object)     // expect: true
-IO.print(fiber is Bool)       // expect: false
-IO.print(fiber.type == Fiber) // expect: true
+System.print(fiber is Fiber)      // expect: true
+System.print(fiber is Object)     // expect: true
+System.print(fiber is Bool)       // expect: false
+System.print(fiber.type == Fiber) // expect: true