From 10f149f359c3bb9c8fbd57e2c19ac520a8da4c69 Mon Sep 17 00:00:00 2001
From: Bob Nystrom <robert@stuffwithstuff.com>
Date: Tue, 1 Dec 2015 08:05:46 -0800
Subject: [PATCH] Add "def" syntax sugar for named function definitions.

This is technically redundant but it makes functional/procedural code
look a *lot* more natural.
---
 example/animals.wren                          | 36 +++++++------
 src/vm/wren_compiler.c                        | 33 ++++++++++++
 test/benchmark/delta_blue.wren                |  6 +--
 test/core/function/call_extra_arguments.wren  |  8 +--
 .../core/function/call_missing_arguments.wren |  2 +-
 test/core/function/equality.wren              |  2 +-
 test/core/list/reduce.wren                    | 15 ++----
 test/language/def/empty_body.wren             |  2 +
 test/language/def/newline_body.wren           |  4 ++
 .../def/newline_in_expression_block.wren      |  4 ++
 .../language/def/no_newline_before_close.wren |  2 +
 test/language/def/parameters.wren             | 50 +++++++++++++++++++
 test/language/def/syntax.wren                 | 29 +++++++++++
 .../for/only_evaluate_sequence_once.wren      |  2 +-
 test/language/for/return_closure.wren         |  2 +-
 test/language/for/return_inside.wren          |  2 +-
 test/language/implicit_call/local.wren        | 12 ++---
 .../implicit_call/module_variable.wren        | 13 +++--
 test/language/module_variable/undefined.wren  |  2 +-
 .../use_in_function_before_definition.wren    |  2 +-
 test/language/precedence.wren                 |  2 +-
 test/language/return/in_function.wren         |  2 +-
 .../return/return_null_if_newline.wren        |  2 +-
 test/language/while/return_closure.wren       |  2 +-
 test/language/while/return_inside.wren        |  2 +-
 test/limit/many_constants.wren                |  2 +-
 test/limit/too_many_constants.wren            |  2 +-
 27 files changed, 178 insertions(+), 64 deletions(-)
 create mode 100644 test/language/def/empty_body.wren
 create mode 100644 test/language/def/newline_body.wren
 create mode 100644 test/language/def/newline_in_expression_block.wren
 create mode 100644 test/language/def/no_newline_before_close.wren
 create mode 100644 test/language/def/parameters.wren
 create mode 100644 test/language/def/syntax.wren

diff --git a/example/animals.wren b/example/animals.wren
index 9dea2065..3147cdf8 100644
--- a/example/animals.wren
+++ b/example/animals.wren
@@ -9,29 +9,27 @@ import "io" for Stdin
 // animals. Internal nodes are yes/no questions that choose which branch to
 // explore.
 
-class Node {
-  // Reads a "yes" or "no" (or something approximating) those and returns true
-  // if yes was entered.
-  promptYesNo(prompt) {
-    while (true) {
-      var line = promptString(prompt)
+// Reads a "yes" or "no" (or something approximating) those and returns true
+// if yes was entered.
+def promptYesNo(prompt) {
+  while (true) {
+    var line = promptString(prompt)
 
-      if (line.startsWith("y") || line.startsWith("Y")) return true
-      if (line.startsWith("n") || line.startsWith("N")) return false
+    if (line.startsWith("y") || line.startsWith("Y")) return true
+    if (line.startsWith("n") || line.startsWith("N")) return false
 
-      // Quit.
-      if (line.startsWith("q") || line.startsWith("Q")) Fiber.yield()
-    }
-  }
-
-  // Writes a prompt and reads a string of input.
-  promptString(prompt) {
-    System.write("%(prompt) ")
-    return Stdin.readLine()
+    // Quit.
+    if (line.startsWith("q") || line.startsWith("Q")) Fiber.yield()
   }
 }
 
-class Animal is Node {
+// Writes a prompt and reads a string of input.
+def promptString(prompt) {
+  System.write("%(prompt) ")
+  return Stdin.readLine()
+}
+
+class Animal {
   construct new(name) {
     _name = name
   }
@@ -56,7 +54,7 @@ class Animal is Node {
   }
 }
 
-class Question is Node {
+class Question {
   construct new(question, ifYes, ifNo) {
     _question = question
     _ifYes = ifYes
diff --git a/src/vm/wren_compiler.c b/src/vm/wren_compiler.c
index 0d069967..bd489a7d 100644
--- a/src/vm/wren_compiler.c
+++ b/src/vm/wren_compiler.c
@@ -81,6 +81,7 @@ typedef enum
   TOKEN_BREAK,
   TOKEN_CLASS,
   TOKEN_CONSTRUCT,
+  TOKEN_DEF,
   TOKEN_ELSE,
   TOKEN_FALSE,
   TOKEN_FOR,
@@ -490,6 +491,7 @@ static Keyword keywords[] =
   {"break",     5, TOKEN_BREAK},
   {"class",     5, TOKEN_CLASS},
   {"construct", 9, TOKEN_CONSTRUCT},
+  {"def",       3, TOKEN_DEF},
   {"else",      4, TOKEN_ELSE},
   {"false",     5, TOKEN_FALSE},
   {"for",       3, TOKEN_FOR},
@@ -2575,6 +2577,7 @@ GrammarRule rules[] =
   /* TOKEN_BREAK         */ UNUSED,
   /* TOKEN_CLASS         */ UNUSED,
   /* TOKEN_CONSTRUCT     */ { NULL, NULL, constructorSignature, PREC_NONE, NULL },
+  /* TOKEN_DEF           */ UNUSED,
   /* TOKEN_ELSE          */ UNUSED,
   /* TOKEN_FALSE         */ PREFIX(boolean),
   /* TOKEN_FOR           */ UNUSED,
@@ -3277,6 +3280,32 @@ static void import(Compiler* compiler)
   } while (match(compiler, TOKEN_COMMA));
 }
 
+// Compiles a "def" function definition statement.
+static void functionDefinition(Compiler* compiler)
+{
+  // Create a variable to store the function in.
+  int slot = declareNamedVariable(compiler);
+  Token name = compiler->parser->previous;
+  
+  Compiler fnCompiler;
+  initCompiler(&fnCompiler, compiler->parser, compiler, true);
+  
+  // Make a dummy signature to track the arity.
+  Signature signature = { "", 0, SIG_METHOD, 0 };
+  
+  parameterList(&fnCompiler, &signature);
+  
+  fnCompiler.numParams = signature.arity;
+  
+  consume(compiler, TOKEN_LEFT_BRACE, "Expect '{' to begin function body.");
+  finishBody(&fnCompiler, false);
+  
+  // Use the function's declared name.
+  endCompiler(&fnCompiler, name.start, name.length);
+  
+  defineVariable(compiler, slot);
+}
+
 // Compiles a "var" variable definition statement.
 static void variableDefinition(Compiler* compiler)
 {
@@ -3310,6 +3339,10 @@ void definition(Compiler* compiler)
   {
     classDefinition(compiler, false);
   }
+  else if (match(compiler, TOKEN_DEF))
+  {
+    functionDefinition(compiler);
+  }
   else if (match(compiler, TOKEN_FOREIGN))
   {
     consume(compiler, TOKEN_CLASS, "Expect 'class' after 'foreign'.");
diff --git a/test/benchmark/delta_blue.wren b/test/benchmark/delta_blue.wren
index b64083d0..17af321d 100644
--- a/test/benchmark/delta_blue.wren
+++ b/test/benchmark/delta_blue.wren
@@ -602,7 +602,7 @@ var total = 0
 // constraint so it cannot be accomodated. The cost in this case is,
 // of course, very low. Typical situations lie somewhere between these
 // two extremes.
-var chainTest = Fn.new {|n|
+def chainTest(n) {
   ThePlanner = Planner.new()
   var prev = null
   var first = null
@@ -627,7 +627,7 @@ var chainTest = Fn.new {|n|
   }
 }
 
-var change = Fn.new {|v, newValue|
+def change(v, newValue) {
   var edit = EditConstraint.new(v, PREFERRED)
   var plan = ThePlanner.extractPlanFromConstraints([edit])
   for (i in 0...10) {
@@ -642,7 +642,7 @@ var change = Fn.new {|v, newValue|
 // other by a simple linear transformation (scale and offset). The
 // time is measured to change a variable on either side of the
 // mapping and to change the scale and offset factors.
-var projectionTest = Fn.new {|n|
+def projectionTest(n) {
   ThePlanner = Planner.new()
   var scale = Variable.new("scale", 10)
   var offset = Variable.new("offset", 1000)
diff --git a/test/core/function/call_extra_arguments.wren b/test/core/function/call_extra_arguments.wren
index 0b68e893..cb074e32 100644
--- a/test/core/function/call_extra_arguments.wren
+++ b/test/core/function/call_extra_arguments.wren
@@ -1,7 +1,7 @@
-var f0 = Fn.new { System.print("zero") }
-var f1 = Fn.new {|a| System.print("one %(a)") }
-var f2 = Fn.new {|a, b| System.print("two %(a) %(b)") }
-var f3 = Fn.new {|a, b, c| System.print("three %(a) %(b) %(c)") }
+def f0() { System.print("zero") }
+def f1(a) { System.print("one %(a)") }
+def f2(a, b) { System.print("two %(a) %(b)") }
+def f3(a, b, c) { System.print("three %(a) %(b) %(c)") }
 
 f0("a") // expect: zero
 f0("a", "b") // expect: zero
diff --git a/test/core/function/call_missing_arguments.wren b/test/core/function/call_missing_arguments.wren
index e02f56f3..98286533 100644
--- a/test/core/function/call_missing_arguments.wren
+++ b/test/core/function/call_missing_arguments.wren
@@ -1,2 +1,2 @@
-var f2 = Fn.new {|a, b| System.print(a + b) }
+def f2(a, b) { System.print(a + b) }
 f2("a") // expect runtime error: Function expects more arguments.
diff --git a/test/core/function/equality.wren b/test/core/function/equality.wren
index 2164915b..c7d80d7f 100644
--- a/test/core/function/equality.wren
+++ b/test/core/function/equality.wren
@@ -11,6 +11,6 @@ System.print(Fn.new { 123 } != false)     // expect: true
 System.print(Fn.new { 123 } != "fn 123")  // expect: true
 
 // Equal by identity.
-var f = Fn.new { 123 }
+def f() { 123 }
 System.print(f == f) // expect: true
 System.print(f != f) // expect: false
diff --git a/test/core/list/reduce.wren b/test/core/list/reduce.wren
index f2a92a8f..e4d93784 100644
--- a/test/core/list/reduce.wren
+++ b/test/core/list/reduce.wren
@@ -1,14 +1,7 @@
 var a = [1, 4, 2, 1, 5]
-var b = ["W", "o", "r", "l", "d"]
-var max = Fn.new {|a, b| a > b ? a : b }
-var sum = Fn.new {|a, b| a + b }
 
-System.print(a.reduce(max)) // expect: 5
-System.print(a.reduce(10, max)) // expect: 10
+System.print(a.reduce {|a, b| a > b ? a : b }) // expect: 5
+System.print(a.reduce(10) {|a, b| a > b ? a : b }) // expect: 10
 
-System.print(a.reduce(sum)) // expect: 13
-System.print(a.reduce(-1, sum)) // expect: 12
-
-// sum also concatenates strings
-System.print(b.reduce("Hello ", sum)) // expect: Hello World
-System.print(b.reduce(sum)) // expect: World
+System.print(a.reduce {|a, b| a + b }) // expect: 13
+System.print(a.reduce(-1) {|a, b| a + b }) // expect: 12
diff --git a/test/language/def/empty_body.wren b/test/language/def/empty_body.wren
new file mode 100644
index 00000000..e837f8d6
--- /dev/null
+++ b/test/language/def/empty_body.wren
@@ -0,0 +1,2 @@
+def f() {}
+System.print(f()) // expect: null
diff --git a/test/language/def/newline_body.wren b/test/language/def/newline_body.wren
new file mode 100644
index 00000000..2cf9c77c
--- /dev/null
+++ b/test/language/def/newline_body.wren
@@ -0,0 +1,4 @@
+def f() {
+  // Hi.
+}
+System.print(f()) // expect: null
diff --git a/test/language/def/newline_in_expression_block.wren b/test/language/def/newline_in_expression_block.wren
new file mode 100644
index 00000000..4613ec65
--- /dev/null
+++ b/test/language/def/newline_in_expression_block.wren
@@ -0,0 +1,4 @@
+def f() { System.print("ok") // expect error
+}
+
+f()
diff --git a/test/language/def/no_newline_before_close.wren b/test/language/def/no_newline_before_close.wren
new file mode 100644
index 00000000..932d1450
--- /dev/null
+++ b/test/language/def/no_newline_before_close.wren
@@ -0,0 +1,2 @@
+def f() {
+  System.print("ok") } // expect error
\ No newline at end of file
diff --git a/test/language/def/parameters.wren b/test/language/def/parameters.wren
new file mode 100644
index 00000000..e6b9e1a8
--- /dev/null
+++ b/test/language/def/parameters.wren
@@ -0,0 +1,50 @@
+def f0() { 0 }
+System.print(f0()) // expect: 0
+
+def f1(a) { a }
+System.print(f1(1)) // expect: 1
+
+def f2(a, b) { a + b }
+System.print(f2(1, 2)) // expect: 3
+
+def f3(a, b, c) { a + b + c }
+System.print(f3(1, 2, 3)) // expect: 6
+
+def f4(a, b, c, d) { a + b + c + d }
+System.print(f4(1, 2, 3, 4)) // expect: 10
+
+def f5(a, b, c, d, e) { a + b + c + d + e }
+System.print(f5(1, 2, 3, 4, 5)) // expect: 15
+
+def f6(a, b, c, d, e, f) { a + b + c + d + e + f }
+System.print(f6(1, 2, 3, 4, 5, 6)) // expect: 21
+
+def f7(a, b, c, d, e, f, g) { a + b + c + d + e + f + g }
+System.print(f7(1, 2, 3, 4, 5, 6, 7)) // expect: 28
+
+def f8(a, b, c, d, e, f, g, h) { a + b + c + d + e + f + g + h }
+System.print(f8(1, 2, 3, 4, 5, 6, 7, 8)) // expect: 36
+
+def f9(a, b, c, d, e, f, g, h, i) { a + b + c + d + e + f + g + h + i }
+System.print(f9(1, 2, 3, 4, 5, 6, 7, 8, 9)) // expect: 45
+
+def f10(a, b, c, d, e, f, g, h, i, j) { a + b + c + d + e + f + g + h + i + j }
+System.print(f10(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)) // expect: 55
+
+def f11(a, b, c, d, e, f, g, h, i, j, k) { a + b + c + d + e + f + g + h + i + j + k }
+System.print(f11(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11)) // expect: 66
+
+def f12(a, b, c, d, e, f, g, h, i, j, k, l) { a + b + c + d + e + f + g + h + i + j + k + l }
+System.print(f12(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)) // expect: 78
+
+def f13(a, b, c, d, e, f, g, h, i, j, k, l, m) { a + b + c + d + e + f + g + h + i + j + k + l + m }
+System.print(f13(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)) // expect: 91
+
+def f14(a, b, c, d, e, f, g, h, i, j, k, l, m, n) { a + b + c + d + e + f + g + h + i + j + k + l + m + n }
+System.print(f14(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)) // expect: 105
+
+def f15(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) { a + b + c + d + e + f + g + h + i + j + k + l + m + n + o }
+System.print(f15(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)) // expect: 120
+
+def f16(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p) { a + b + c + d + e + f + g + h + i + j + k + l + m + n + o + p }
+System.print(f16(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)) // expect: 136
diff --git a/test/language/def/syntax.wren b/test/language/def/syntax.wren
new file mode 100644
index 00000000..5c26907d
--- /dev/null
+++ b/test/language/def/syntax.wren
@@ -0,0 +1,29 @@
+// Single expression body.
+def f() { System.print("ok") } // expect: ok
+f()
+
+// Curly body.
+def g() {
+  System.print("ok") // expect: ok
+}
+g()
+
+// Multiple statements.
+def h() {
+  System.print("1") // expect: 1
+  System.print("2") // expect: 2
+}
+h()
+
+// Extra newlines.
+def i() {
+
+
+  System.print("1") // expect: 1
+
+
+  System.print("2") // expect: 2
+
+
+}
+i()
diff --git a/test/language/for/only_evaluate_sequence_once.wren b/test/language/for/only_evaluate_sequence_once.wren
index 3e056fba..79328a9f 100644
--- a/test/language/for/only_evaluate_sequence_once.wren
+++ b/test/language/for/only_evaluate_sequence_once.wren
@@ -1,4 +1,4 @@
-var f = Fn.new {
+def f() {
   System.print("evaluate sequence")
   return [1, 2, 3]
 }
diff --git a/test/language/for/return_closure.wren b/test/language/for/return_closure.wren
index d083abb2..fb1b7350 100644
--- a/test/language/for/return_closure.wren
+++ b/test/language/for/return_closure.wren
@@ -1,4 +1,4 @@
-var f = Fn.new {
+def f() {
   for (i in [1, 2, 3]) {
     return Fn.new { System.print(i) }
   }
diff --git a/test/language/for/return_inside.wren b/test/language/for/return_inside.wren
index f1eff999..f32c77fd 100644
--- a/test/language/for/return_inside.wren
+++ b/test/language/for/return_inside.wren
@@ -1,4 +1,4 @@
-var f = Fn.new {
+def f() {
   for (i in [1, 2, 3]) {
     return i
   }
diff --git a/test/language/implicit_call/local.wren b/test/language/implicit_call/local.wren
index f3275d84..6c3f6e3c 100644
--- a/test/language/implicit_call/local.wren
+++ b/test/language/implicit_call/local.wren
@@ -1,11 +1,11 @@
 Fn.new {
-  var fn = Fn.new {|arg| System.print(arg) }
+  def f1(arg) { System.print(arg) }
 
-  fn("string") // expect: string
+  f1("string") // expect: string
 
-  fn = Fn.new {|block| System.print(block()) }
-  fn { "block" } // expect: block
+  def f2(block) { System.print(block()) }
+  f2 { "block" } // expect: block
 
-  fn = Fn.new {|a, b, c| System.print("%(a) %(b) %(c())") }
-  fn(1, 2) { 3 } // expect: 1 2 3
+  def f3(a, b, c) { System.print("%(a) %(b) %(c())") }
+  f3(1, 2) { 3 } // expect: 1 2 3
 }()
diff --git a/test/language/implicit_call/module_variable.wren b/test/language/implicit_call/module_variable.wren
index 5cb5505e..57e4472e 100644
--- a/test/language/implicit_call/module_variable.wren
+++ b/test/language/implicit_call/module_variable.wren
@@ -1,9 +1,8 @@
-var fn = Fn.new {|arg| System.print(arg) }
+def f1(arg) { System.print(arg) }
+f1("string") // expect: string
 
-fn("string") // expect: string
+def f2(block) { System.print(block()) }
+f2 { "block" } // expect: block
 
-fn = Fn.new {|block| System.print(block()) }
-fn { "block" } // expect: block
-
-fn = Fn.new {|a, b, c| System.print("%(a) %(b) %(c())") }
-fn(1, 2) { 3 } // expect: 1 2 3
+def f3(a, b, c) { System.print("%(a) %(b) %(c())") }
+f3(1, 2) { 3 } // expect: 1 2 3
diff --git a/test/language/module_variable/undefined.wren b/test/language/module_variable/undefined.wren
index b622d0d8..79821d33 100644
--- a/test/language/module_variable/undefined.wren
+++ b/test/language/module_variable/undefined.wren
@@ -1,4 +1,4 @@
-var fn = Fn.new {
+def fn() {
   System.print(a)
   System.print(b)
 }
diff --git a/test/language/module_variable/use_in_function_before_definition.wren b/test/language/module_variable/use_in_function_before_definition.wren
index 6ff8801d..983c6af1 100644
--- a/test/language/module_variable/use_in_function_before_definition.wren
+++ b/test/language/module_variable/use_in_function_before_definition.wren
@@ -1,4 +1,4 @@
-var f = Fn.new {
+def f() {
   System.print(variable)
 }
 
diff --git a/test/language/precedence.wren b/test/language/precedence.wren
index d5d3ee20..0101b317 100644
--- a/test/language/precedence.wren
+++ b/test/language/precedence.wren
@@ -1,5 +1,5 @@
 // () has higher precedence than unary.
-var fn = Fn.new { 2 }
+def fn() { 2 }
 System.print(-fn()) // expect: -2
 
 // * has higher precedence than +.
diff --git a/test/language/return/in_function.wren b/test/language/return/in_function.wren
index ab5073f3..ebaf5af7 100644
--- a/test/language/return/in_function.wren
+++ b/test/language/return/in_function.wren
@@ -1,4 +1,4 @@
-var f = Fn.new {
+def f() {
   return "ok"
   System.print("bad")
 }
diff --git a/test/language/return/return_null_if_newline.wren b/test/language/return/return_null_if_newline.wren
index 53e7036e..b1315790 100644
--- a/test/language/return/return_null_if_newline.wren
+++ b/test/language/return/return_null_if_newline.wren
@@ -1,4 +1,4 @@
-var f = Fn.new {
+def f() {
   return
   System.print("bad")
 }
diff --git a/test/language/while/return_closure.wren b/test/language/while/return_closure.wren
index e3ecfbf8..fded976f 100644
--- a/test/language/while/return_closure.wren
+++ b/test/language/while/return_closure.wren
@@ -1,4 +1,4 @@
-var f = Fn.new {
+def f() {
   while (true) {
     var i = "i"
     return Fn.new { System.print(i) }
diff --git a/test/language/while/return_inside.wren b/test/language/while/return_inside.wren
index 0a29375a..090ee386 100644
--- a/test/language/while/return_inside.wren
+++ b/test/language/while/return_inside.wren
@@ -1,4 +1,4 @@
-var f = Fn.new {
+def f() {
   while (true) {
     var i = "i"
     return i
diff --git a/test/limit/many_constants.wren b/test/limit/many_constants.wren
index 77edec79..3a5590e0 100644
--- a/test/limit/many_constants.wren
+++ b/test/limit/many_constants.wren
@@ -1,4 +1,4 @@
-var f = Fn.new {
+def f() {
   1
   2
   3
diff --git a/test/limit/too_many_constants.wren b/test/limit/too_many_constants.wren
index 48ea226a..46a8b66d 100644
--- a/test/limit/too_many_constants.wren
+++ b/test/limit/too_many_constants.wren
@@ -1,4 +1,4 @@
-var f = Fn.new {
+def f() {
   1
   2
   3