Make join() require parentheses without a separator.

builtin/core.wren

@@ -78,7 +78,7 @@ class Sequence {
     return result
   }
 
-  join { join("") }
+  join() { join("") }
 
   join(sep) {
     var first = true

doc/site/core/sequence.markdown

@@ -68,17 +68,17 @@ Returns whether the sequence contains any elements.
 This can be more efficient that `count == 0` because this does not iterate over
 the entire sequence.
 
-### **join**(sep)
+### **join**(separator)
 
-Returns a string representation of the sequence. The string representations of
-the elements in the sequence is concatenated with intervening occurrences of
-`sep`.
+Converts every element in the sequence to a string and then joins the results
+together into a single string, each separated by `separator`.
 
-It is a runtime error if `sep` is not a string.
+It is a runtime error if `separator` is not a string.
 
-### **join**
+### **join**()
 
-Calls `join` with the empty string as the separator.
+Converts every element in the sequence to a string and then joins the results
+together into a single string.
 
 ### **map**(transformation)
 

src/vm/wren_core.wren.inc

@@ -80,7 +80,7 @@ static const char* coreModuleSource =
 "    return result\n"
 "  }\n"
 "\n"
-"  join { join(\"\") }\n"
+"  join() { join(\"\") }\n"
 "\n"
 "  join(sep) {\n"
 "    var first = true\n"

test/core/list/join.wren

@@ -5,7 +5,7 @@ System.print([].join(",") == "") // expect: true
 System.print([1, 2, 3].join("")) // expect: 123
 
 // Handle a simple list with no separator.
-System.print([1, 2, 3].join) // expect: 123
+System.print([1, 2, 3].join()) // expect: 123
 
 // Does not quote strings.
 System.print([1, "2", true].join(",")) // expect: 1,2,true

test/core/range/join.wren

@@ -1,4 +1,4 @@
 var a = 1..3
 
-System.print(a.join) // expect: 123
+System.print(a.join()) // expect: 123
 System.print(a.join(", ")) // expect: 1, 2, 3