implicit return for functions

src/ndspkg/compiler/functions.nim

@@ -34,12 +34,6 @@ proc parseArgs(comp: Compiler): int =
 proc parseCall(comp: Compiler) =
   # ( consumed
 
-  # create the call env
-  # current stack before opCall:
-  # ... <funct obj> <arg1> <arg2> <arg3>
-  # opCall converts it to this
-  # ... <ret val> <arg1> <arg2> <arg3>
-
   let argcount = comp.parseArgs()
 
   # emit call

src/ndspkg/compiler/scope.nim

@@ -18,22 +18,17 @@ proc beginScope*(comp: Compiler, function: bool = false) =
   when debugCompiler:
     debugEcho &"Begin scope called for depth {comp.scopes.len} function? {function}"
 
-  if function:
-    scope.labels.add("result")
-    scope.labels.add("function")
-  else:
+  if not function:
     while comp.match(tkLabel):
       let label = comp.previous.text[1..^1]
       scope.labels.add(label)
-
-  if function:
-    # if it's a function scope, the frame will move
-    # access to outside locals is also limited to upvalues and closures
-    comp.stackIndex = 0
-  else:
     # only put the opNil if it's not a function scope, since
     # function scopes are initialized by the caller
     comp.writeChunk(1, opNil)
+  else:
+    # if it's a function scope, the frame will move
+    # access to outside locals is also limited to upvalues and closures
+    comp.stackIndex = 0
 
   for label in scope.labels:
     comp.addLocal(&":{label}", delta = 0)
@@ -48,12 +43,12 @@ proc restore*(comp: Compiler, scope: Scope) =
     debugEcho &"Restored scope: delta {delta}"
 
 proc restoreInFunct*(comp: Compiler, scope: Scope) =
-  let pops = comp.stackIndex
-  comp.writePops(pops)
+  #let pops = comp.stackIndex
+  #comp.writePops(pops)
 
   comp.stackIndex = scope.goalStackIndex
-  when debugCompiler:
-    debugEcho &"Restored function scope: delta {pops}; new stackindex: {comp.stackIndex}"
+  #when debugCompiler:
+  #  debugEcho &"Restored function scope: delta {pops}; new stackindex: {comp.stackIndex}"
 
 proc jumpToEnd*(comp: Compiler, scope: Scope) =
   ## Jumps to the end of scope, does not affect stackIndex
@@ -93,6 +88,10 @@ proc endScope*(comp: Compiler): Scope =
     comp.restore(popped)
   # patch jumps to after the scope (such jumps from breaks emit the pops before jumping)
   for jump in popped.jumps:
+    when assertionsCompiler:
+      if function:
+        # all jumps should only happen to named block expressions
+        comp.error("Assertion failed: jump attempt to end function.")
     comp.patchJump(jump, popped.goalStackIndex)
   if function:
     comp.writeChunk(0, opReturn)

src/ndspkg/vm.nim

@@ -226,7 +226,12 @@ proc run*(chunk: Chunk): InterpretResult =
         if frames.len() == 1:
           break
         else:
-          ip = frames.pop().returnIp # remove frame that's over
+          let retval = stack.pop()
+          let oldframe = frames.pop()
+          ip = oldframe.returnIp # remove frame that's over
+          let length = stack.len() - oldframe.stackBottom
+          stack.deleteTopN(length)
+          stack.push(retval)
       of opTrue:
         stack.add(fromBool(true))
       of opFalse:
@@ -303,15 +308,8 @@ proc run*(chunk: Chunk): InterpretResult =
           runtimeError(&"Wrong number of arguments, expected {arity}, got {argcount}.")
           break
       of opCall:
-        # create the call env
-        # current stack before opCall:
-        # ... <funct obj> <arg1> <arg2> <arg3>
-        # opCall converts it to this
-        # ... <ret val> <arg1> <arg2> <arg3>
         let argcount = ip.readUI8()
         let funct = stack.getIndexNeg(argcount)
-
-        stack.setIndexNeg(argcount, fromNil()) # replace the function with nil: this is the return value slot
         funct.call(argcount):
           break
       of opCreateList:

tests/break.nds

@@ -44,13 +44,13 @@
 
 //expect:5.0
 
-var f = funct() {
+var f = funct() { @result
   var y = 1;
   var z = 3;
   var p = 1;
   :result = y + (z + p);
   {
-    break @function;
+    break @result;
   };
   :result = 10;
 };
@@ -60,7 +60,7 @@ print (f());
 //expect:15.0
 
 f = funct(m, n)
-  :result = m + n
+  m + n
 ;
 
 print (f(f(5, 5), 5));
@@ -69,7 +69,7 @@ print (f(f(5, 5), 5));
 //expect:10.0
 
 var g = funct()
-  :result = {@a
+  {@a
     :a = { @b
       :b = { @c
         :c = 10;
@@ -83,7 +83,7 @@ print (g());
 //expect:9.0
 
 var h = funct()
-  :result = {@a
+  {@a
     :a = { @b
       :b = { @c
         :a = 3;

tests/closures.nds

@@ -1,16 +1,16 @@
 // cascade
 
-var f1 = funct() {
+var f1 = funct() { @result
   var x = 1;
   var y = 5;
-  :result = funct() {
+  :result = funct() { @result
     var z = 8;
     print (x);
     x = x + 1;
-    :result = funct() {
+    :result = funct() { @result
       print (x);
       x = x + 1;
-      :result = funct() {
+      :result = funct() { @result
         print (x);
         print (y);
         print (z);
@@ -33,7 +33,7 @@ f1()()()()();
 
 // capturing closures in lists:
 
-var f = funct() {
+var f = funct() { @result
   var y = 5;
   var x = @[
     funct() print (y),
@@ -52,7 +52,7 @@ inst[0]();
 
 // multiple different labels
 
-var f2 = funct() { 
+var f2 = funct() { @result
   var x = { @a @b
     // this captures the internal value, not whatever it returns is assigned to
     :result = @{
@@ -73,7 +73,7 @@ inst2["get"]();
 // capturing args
 
 var argcap = funct(n)
-  :result = funct() print (n)
+  funct() print (n)
 ;
 
 //expect:8.1
@@ -82,12 +82,12 @@ argcap(8.1)();
 
 // oop: constructors, getters, setters
 
-var newAnimal = funct(species, color) {
+var newAnimal = funct(species, color) { @result
   var species = species; // copy it so that it's mutable, if args ever get immutable
   var animal = @{
-    ["getSpecies"] = funct() :result = species,
+    ["getSpecies"] = funct() species,
     ["setSpecies"] = funct(newSpecies) species = newSpecies,
-    ["getColor"] = funct() :result = color, // this captures an argument directly
+    ["getColor"] = funct() color, // this captures an argument directly
   };
   :result = animal;
 };
@@ -116,7 +116,7 @@ print (turtle["getSpecies"]());
 
 // 1:
 
-var makeClosure = funct(value) {
+var makeClosure = funct(value) { @result
   var closure = funct() {
     print (value);
   };
@@ -132,9 +132,9 @@ bagel();
 
 // 2: (multi level closures)
 
-var outer = funct() {
+var outer = funct() { @result
   var x = "value";
-  var middle = funct() {
+  var middle = funct() { @result
     var inner = funct() {
       print (x);
     };
@@ -157,7 +157,7 @@ in();
 
 // 3: (mixed multi level closures)
 
-outer = funct() {
+outer = funct() { @result
   var a = 1;
   var b = 2;
   var result;
@@ -170,7 +170,7 @@ outer = funct() {
     result = inner;
   };
   middle();
-  :result = funct() :result = result;
+  :result = funct() result;
 };
 
 //expect:10.0
@@ -238,7 +238,7 @@ globalGet();
 
 // bonus: the last one with a list twist
 
-var bonus = funct() {
+var bonus = funct() { @result
   var a = 1;
   var f = funct() {
     print (a);

tests/collections.nds

@@ -1,8 +1,8 @@
 // a test about collections, WIP
 
-var returnlist = funct() {
-  :result = @[1, 2, 3, 4];
-};
+var returnlist = funct()
+  @[1, 2, 3, 4]
+;
 
 //expect:3.0
 print (returnlist()[2]);

tests/precedence.nds

@@ -15,7 +15,7 @@ print (-((3 + 2) * 2) + 1);
 
 // calls and indexes
 
-var returnlist = funct() {
+var returnlist = funct() { @result
   :result = @[];
   :result[0] = 4;
   :result[1] = 6;
@@ -27,9 +27,9 @@ var returnlist = funct() {
 print (returnlist()[2]);
 
 // priority over unary
-var truesayer = funct() {
-  :result = true;
-};
+var truesayer = funct()
+  true
+;
 
 //expect:false
 print (!truesayer());

tests/sugar.nds

@@ -3,11 +3,11 @@
 
 // :: piping function call
 
-var double = funct(num) :result = num * 2;
+var double = funct(num) num * 2;
 
 var four = 2 :: double();
 
-var multiply = funct(num, factor) :result = num * factor;
+var multiply = funct(num, factor) num * factor;
 
 var six = 2 :: multiply(3);
 
@@ -65,7 +65,7 @@ class->method;
 
 var multiplier = @{
   multiple = 5,
-  do = funct(self, arg) :result = self.multiple * arg,
+  do = funct(self, arg) self.multiple * arg,
 };
 
 multiplier->do(7) :: print;
@@ -74,7 +74,7 @@ multiplier->do(7) :: print;
 // -> method call syntax with :: - check for precedence
 
 var returner = @{
-  method = funct(self) :result = funct(n) :result = n * 2
+  method = funct(self) funct(n) n * 2
 };
 
 1.7 :: returner->method :: print;