gypsum: change syntax for unit literal from {} to ()

codeswitch/test/BinaryCompatibility/foo.gy

@@ -19,7 +19,7 @@ def test-load-store-field =
   o.y = "baz"
   assert-eq(56i64, o.x)
   assert-eq("baz", o.y)
-  {}
+  ()
 
 def test-load-store-inherited-field =
   let o = DerivedFieldClass()
@@ -29,33 +29,33 @@ def test-load-store-inherited-field =
   o.y = "baz"
   assert-eq(56i64, o.x)
   assert-eq("baz", o.y)
-  {}
+  ()
 
 def test-call-class-method =
   let o = MethodClass()
   assert-eq(34i64, o.f)
   assert-eq("bar", o.g)
-  {}
+  ()
 
 def test-call-inherited-class-method =
   let o = DerivedMethodClass()
   assert-eq(34i64, o.f)
   assert-eq("bar", o.g)
-  {}
+  ()
 
 def test-call-inherited-trait-method =
   let o = DerivedClassFromTrait()
   assert-eq(34i64, o.f)
   assert-eq("bar", o.g)
-  {}
+  ()
 
 def main =
   test-load-store-field
   test-load-store-inherited-field
   test-call-class-method
   test-call-inherited-class-method
   test-call-inherited-trait-method
-  {}
+  ()
 
 def assert-eq(expected: String, actual: String) =
   if (expected != actual)

codeswitch/test/arithmetic-evaluation-example.gy

@@ -137,5 +137,5 @@ def main =
     MulExpr(AddExpr(ConstExpr(Integer(1)), ConstExpr(Integer(2))), AddExpr(ConstExpr(Integer(3)), ConstExpr(Integer(0))))
   let opt-expr = optimize(unopt-expr)
   match (opt-expr)
-    case MulExpr(ConstExpr(a), ConstExpr(b)) if a.value == 3 && b.value == 3 => {}
+    case MulExpr(ConstExpr(a), ConstExpr(b)) if a.value == 3 && b.value == 3 => ()
     case _ => throw Exception()

codeswitch/test/bitset-example.gy

@@ -6,7 +6,7 @@
 import std.IllegalArgumentException
 
 final class BitSet
-  private def this = {}
+  private def this = ()
 
   static def create(max: i32) =
     let bytes-needed = (max + 7i32) / 8i32

codeswitch/test/box-example.gy

@@ -8,7 +8,7 @@ class Box[static T <: Object >: Nothing](private var value: T)
 
   def set(new-value: T) =
     value = new-value
-    {}
+    ()
 
   def contains-same-value[static S](other: Box[S]) = value === other.value
 

codeswitch/test/dict.gy

@@ -30,12 +30,12 @@ def test-empty-dict =
   try
     it.next
     throw AssertionException()
-  catch (e: NoSuchElementException) {}
+  catch (e: NoSuchElementException) ()
 
   assert-false(dict.get(I32.of(42i32)).is-defined)
   assert-eq[I32](I32.of(12i32), dict.get-or-else(I32.of(42i32), I32.of(12i32)))
   assert-false(dict.remove(I32.of(42i32)).is-defined)
-  {}
+  ()
 
 def test-insert-retrieve-remove =
   let dict = Dict[I32, I32]()
@@ -82,4 +82,4 @@ def main =
   test-empty-dict
   test-insert-retrieve-remove
   test-iter
-  {}
+  ()

codeswitch/test/finally-exception-in-catch.gy

@@ -14,7 +14,7 @@ def main =
   try
     inner-fn(outer-exn)
   catch
-    case exn if exn === outer-exn && finally-executed => {}
+    case exn if exn === outer-exn && finally-executed => ()
 
 def inner-fn(outer-exn: Exception): unit =
   let inner-exn = Exception()

codeswitch/test/large-alloc.gy

@@ -11,7 +11,7 @@ def test-bad-alloc(length: i32) =
     new(length) Foo
     throw Exception()
   catch (e: OutOfMemoryException)
-    {}
+    ()
 
 def main =
   test-bad-alloc(0x20000000i32)

codeswitch/test/load-uninitialized.gy

@@ -16,22 +16,22 @@ def load-uninitialized-field =
     foo.bar
     throw Exception()
   catch (e: UninitializedException)
-    {}
+    ()
 
 def load-uninitialized-element =
   let foo = new(1i32) Foo
   try
     foo.get(0i32)
     throw Exception()
   catch (e: UninitializedException)
-    {}
+    ()
 
 def load-uninitialized-global =
   try
     global
     throw Exception()
   catch (e: UninitializedException)
-    {}
+    ()
 
 def load-uninitialized-capture =
   var x: String
@@ -42,7 +42,7 @@ def load-uninitialized-capture =
     f
     throw Exception()
   catch (e: UninitializedException)
-    {}
+    ()
 
 def main =
   load-uninitialized-field

codeswitch/test/match-static-dynamic.gy

@@ -16,5 +16,5 @@ class FullBox[static T](value: T) <: Box[T]
 def main =
   let box = FullBox[String]("foo")
   match (box)
-    case FullBox[String](s) if s == "foo" => {}
+    case FullBox[String](s) if s == "foo" => ()
     case _ => throw Exception()

codeswitch/test/primitives-to-string.gy

@@ -3,7 +3,7 @@ def check-eq(expected: String, actual: String) =
     throw Exception()
 
 def main =
-  check-eq("unit", {}.to-string)
+  check-eq("unit", ().to-string)
 
   // check-eq("true", true.to-string)
   // check-eq("false", false.to-string)

codeswitch/test/result.gy

@@ -36,5 +36,5 @@ def main =
   catch (_: Exception) true
   assert-true(e)
   match (err)
-    case Err[String](s) if s === message => {}
+    case Err[String](s) if s === message => ()
     case _ => throw AssertionException()

codeswitch/test/return-nested-finally.gy

@@ -20,7 +20,7 @@ def f =
         inner-finally-executed = true
     catch (_)
       catch-executed = true
-      {}
+      ()
   finally
     outer-finally-executed = true
 

codeswitch/test/set.gy

@@ -31,7 +31,7 @@ def test-empty-set =
   try
     it.next
     throw AssertionException()
-  catch (e: NoSuchElementException) {}
+  catch (e: NoSuchElementException) ()
 
   assert-false(set.contains(I32.of(1i32)))
   assert-false(set.remove(I32.of(1i32)))
@@ -80,4 +80,4 @@ def main =
   test-empty-set
   test-insert-remove
   test-iter
-  {}
+  ()

codeswitch/test/std-io-length.gy

@@ -14,10 +14,10 @@ def read-all(reader: Reader): i64 =
     let length = reader.read(buffer, 0i32, buffer.length)
     if (length == 0i32)
       done = true
-      {}
+      ()
     else
       total-length += length.to-i64
-      {}
+      ()
   total-length
 
 def main =

codeswitch/test/string-access.gy

@@ -17,10 +17,10 @@ def main =
     s.get(-1i32)
     throw Exception()
   catch (e: ArrayIndexOutOfBoundsException)
-    {}
+    ()
 
   try
     s.get(5i32)
     throw Exception()
   catch (e: ArrayIndexOutOfBoundsException)
-    {}
+    ()

codeswitch/test/uninitialized-global.gy

@@ -11,4 +11,4 @@ def main =
   try
     g
     throw Exception()
-  catch (_: UninitializedException) {}
+  catch (_: UninitializedException) ()

examples/bitset.gy

@@ -15,7 +15,7 @@ import std.IllegalArgumentException
 final class BitSet
   // We declare a private constructor so clients are forced to use the `create` method to
   // build new instances. `BitSet` has no normal fields, so this method does nothing.
-  private def this = {}
+  private def this = ()
 
   // This method creates new `BitSet` objects. We give it a maximum integer that can be stored
   // in the set, and it calculates the number of bytes needed, then allocates a new `BitSet`.

examples/box.gy

@@ -18,7 +18,7 @@ class Box[static T <: Object >: Nothing](private var value: T)
 
   def set(new-value: T) =
     value = new-value
-    {}
+    ()
 
   // Of course methods may have their own type parameters.
   def contains-same-value[static S](other: Box[S]) = value === other.value

gypsum/format.py

@@ -414,7 +414,7 @@ def visitGroupExpression(self, node):
         self._write(")")
 
     def visitUnitLiteral(self, node):
-        self._write("{}")
+        self._write("()")
 
     def visitIntegerLiteral(self, node):
         self._write(node.text)

gypsum/parser.py

@@ -42,7 +42,6 @@
     INDENT,
     INTEGER,
     LAMBDA,
-    LBRACE,
     LBRACK,
     LET,
     LPAREN,
@@ -114,7 +113,6 @@ def __init__(self, fileName, tokens):
     EXPR_START_TOKENS = (
         LBRACK,
         LPAREN,
-        LBRACE,
         IF,
         ELSE,
         WHILE,
@@ -248,8 +246,12 @@ def varDefn(self, l, ats):
         pat = self.pattern()
         if self._peekTag() is EQ:
             self._next()
-            # Use maybeTupleExpr instead of expr to avoid assignments.
-            e = self.maybeTupleExpr()
+            # TODO: this hack is here to avoid assignment. Remove when assignment is
+            # no longer an expression.
+            if self._peekTag() is NEWLINE:
+                e = self.blockExpr()
+            else:
+                e = self.maybeTupleExpr()
         else:
             e = None
         d = ast.VariableDefinition(ats, var, pat, e, None, self._location(l))
@@ -472,12 +474,18 @@ def literalPattern(self):
         return p
 
     def groupPattern(self):
-        l = self._nextTag(LPAREN)
-        p = self.pattern()
-        self._nextTag(RPAREN)
-        g = ast.GroupPattern(p, None, self._location(l.location))
-        self._tailComment(g)
-        return g
+        l = self._nextTag(LPAREN).location
+        if self._peekTag() is RPAREN:
+            self._next()
+            loc = self._location(l)
+            lit = ast.UnitLiteral(loc)
+            p = ast.LiteralPattern(lit, None, loc)
+        else:
+            i = self.pattern()
+            self._nextTag(RPAREN)
+            p = ast.GroupPattern(i, None, self._location(l))
+        self._tailComment(p)
+        return p
 
     # Types
     def ty(self):
@@ -585,7 +593,10 @@ def typeFlags(self):
 
     # Expressions
     def expr(self):
-        return self.maybeAssignExpr()
+        if self._peekTag() is NEWLINE:
+            return self.blockExpr()
+        else:
+            return self.maybeAssignExpr()
 
     def maybeAssignExpr(self):
         es = self._parseRepSep(self.maybeTupleExpr, EQ)
@@ -653,7 +664,9 @@ def _associativity(self, op):
 
     def maybeCallExpr(self):
         e = self.receiverExpr()
-        tag = self._peek().tag
+        if self._peekTag(-1) is OUTDENT:
+            return e
+        tag = self._peekTag()
         while tag in (DOT, LBRACK, LPAREN):
             if tag is DOT:
                 self._next()
@@ -681,7 +694,7 @@ def receiverExpr(self):
         tag = self._peek().tag
         if tag is OPERATOR:
             e = self.unaryExpr()
-        elif tag in (INTEGER, FLOAT, STRING, TRUE, FALSE, NULL, LBRACE):
+        elif tag in (INTEGER, FLOAT, STRING, TRUE, FALSE, NULL):
             e = self.literalExpr()
         elif tag is SYMBOL:
             e = self.varExpr()
@@ -707,8 +720,6 @@ def receiverExpr(self):
             e = self.throwExpr()
         elif tag is TRY:
             e = self.tryExpr()
-        elif tag is NEWLINE:
-            e = self.blockExpr()
         elif tag is LAMBDA:
             e = self.lambdaExpr()
         elif tag is RETURN:
@@ -751,12 +762,18 @@ def superExpr(self):
         return e
 
     def groupExpr(self):
-        l = self._nextTag(LPAREN)
-        e = self.expr()
-        r = self._nextTag(RPAREN)
-        g = ast.GroupExpression(e, None, l.location.combine(r.location))
-        self._tailComment(g)
-        return g
+        l = self._nextTag(LPAREN).location
+        if self._peekTag() is RPAREN:
+            self._next()
+            loc = self._location(l)
+            lit = ast.UnitLiteral(loc)
+            e = ast.LiteralExpression(lit, None, loc)
+        else:
+            i = self.expr()
+            self._nextTag(RPAREN)
+            e = ast.GroupExpression(i, None, self._location(l))
+        self._tailComment(e)
+        return e
 
     def newArrayExpr(self):
         l = self._nextTag(NEW)
@@ -943,7 +960,7 @@ def returnExpr(self):
     # Literals
     def literal(self):
         tok = self._peek()
-        if tok.tag is LBRACE:
+        if tok.tag is LPAREN:
             return self.unitLiteral()
         elif tok.tag is INTEGER:
             return self.intLiteral()
@@ -963,8 +980,8 @@ def literal(self):
         return lit
 
     def unitLiteral(self):
-        l = self._nextTag(LBRACE).location
-        self._nextTag(RBRACE)
+        l = self._nextTag(LPAREN).location
+        self._nextTag(RPAREN)
         return ast.UnitLiteral(self._location(l))
 
     def intLiteral(self):