sugars: :: and table . op; allow for reading existing locals of the same name in var statements

src/ndspkg/chunk.nim

@@ -9,6 +9,7 @@ type
     opClosure, # closures
     opPop, opPopSA, opPopA # pop
     opNegate, opNot # unary
+    opSwap, # stack manipulation
     opAdd, opSubtract, opMultiply, opDivide, # math
     opEqual, opGreater, opLess, # comparison
     opTrue, opFalse, opNil, # literal
@@ -91,6 +92,7 @@ proc writeConstant*(ch: var Chunk, constant: NdValue, line: int): int =
 const simpleInstructions = {
   opReturn,
   opPop,
+  opSwap,
   opNegate, opNot,
   opAdd, opSubtract, opMultiply, opDivide,
   opEqual, opGreater, opLess,

src/ndspkg/compiler/collections.nim

@@ -2,9 +2,9 @@
 
 import ../scanner
 import ../chunk
+import ../types/value
+import bitops
 
-# the following order of imports here is important
-# it defines the allowed dependency precedence between the compiler files
 import types
 import utils
 import precedence
@@ -68,3 +68,17 @@ proc parseIndex(comp: Compiler) =
     comp.writeChunk(-1, opGetIndex)
 
 tkLeftBracket.genRule(nop, parseIndex, pcIndex)
+
+proc parseDotIndex(comp: Compiler) =
+  # the index
+  comp.consume(tkIdentifier, "Identifier expected after dot index.")
+  let index = comp.previous.text.fromNimString()
+  comp.writeConstant(index)
+
+  if comp.match(tkEqual):
+    comp.parsePrecedence(pcNonAssignTop)
+    comp.writeChunk(-2, opSetIndex)
+  else:
+    comp.writeChunk(-1, opGetIndex)
+
+tkDot.genRule(nop, parseDotIndex, pcIndex)

src/ndspkg/compiler/controlflow.nim

@@ -3,8 +3,6 @@
 import ../scanner
 import ../chunk
 
-# the following order of imports here is important
-# it defines the allowed dependency precedence between the compiler files
 import types
 import utils
 import precedence
@@ -18,7 +16,8 @@ proc ifExpr(comp: Compiler) =
   comp.expression()
   comp.consume(tkRightParen, "Expect ')' after condition.")
 
-  let thenJump = comp.emitJump(0, opJumpIfFalse)
+  var thenStacklen = 0
+  let thenJump = comp.emitJump(0, opJumpIfFalse, thenStacklen)
 
   # conditional code that can be jumped over must leave the stack in tact!
 
@@ -26,40 +25,44 @@ proc ifExpr(comp: Compiler) =
   comp.expression()
   # net change to stack: -1 + 1 = 0
   
-  let elseJump = comp.emitJump(0, opJump)
-  comp.patchJump(thenJump)
+  var elseStacklen = 0
+  let elseJump = comp.emitJump(0, opJump, elseStacklen)
+  comp.patchJump(thenJump, thenStacklen)
 
   if comp.match(tkElse):
     comp.writeChunk(-1, opPop)
     comp.expression()
   
-  comp.patchJump(elseJump)
+  comp.patchJump(elseJump, elseStacklen)
 
 
 tkIf.genRule(ifExpr, nop, pcNone)
 
 proc andExpr(comp: Compiler) =
-  let endJump = comp.emitJump(0, opJumpIfFalse)
+  var stacklen = 0
+  let endJump = comp.emitJump(0, opJumpIfFalse, stacklen)
 
   comp.writeChunk(-1, opPop)
   comp.parsePrecedence(pcAnd)
   # net effect on stack: -1 + 1 = 0
 
-  comp.patchJump(endJump)
+  comp.patchJump(endJump, stacklen)
 
 tkAnd.genRule(nop, andExpr, pcAnd)
 
 proc orExpr(comp: Compiler) =
-  let elseJump = comp.emitJump(0, opJumpIfFalse)
-  let endJump = comp.emitJump(0, opJump)
+  var elseStacklen = 0
+  var endStacklen = 0
+  let elseJump = comp.emitJump(0, opJumpIfFalse, elseStacklen)
+  let endJump = comp.emitJump(0, opJump, endStacklen)
 
-  comp.patchJump(elseJump)
+  comp.patchJump(elseJump, elseStacklen)
 
   comp.writeChunk(-1, opPop)
   comp.parsePrecedence(pcOr)
   # net effect on stack: -1 + 1 = 0
 
-  comp.patchJump(endJump)
+  comp.patchJump(endJump, endStacklen)
 
 tkOr.genRule(nop, orExpr, pcOr)
 
@@ -67,12 +70,14 @@ proc parseWhile(comp: Compiler) =
 
   comp.writeChunk(1, opNil) # return value
   let loopStart = comp.chunk.len
+  let loopStacklen = comp.stackIndex
   comp.consume(tkLeftParen, "Expect '(' after 'while'.")
   # condition
   comp.expression()
   comp.consume(tkRightParen, "Expect ')' after condition.")
 
-  let exitJump = comp.emitJump(-1, opJumpIfFalsePop)
+  var exitStacklen = 0
+  let exitJump = comp.emitJump(-1, opJumpIfFalsePop, exitStacklen)
   # this cannot be handled with just opPop, since the net change in the
   # stack size inside code that is conditional must be 0!
 
@@ -81,7 +86,7 @@ proc parseWhile(comp: Compiler) =
   comp.expression()
   # net stack change: 1 + -1 = 0
 
-  comp.emitLoop(loopstart = loopStart, delta = 0, op = opLoop)
-  comp.patchJump(exitJump)
+  comp.emitLoop(loopstart = loopStart, delta = 0, op = opLoop, loopStacklen)
+  comp.patchJump(exitJump, exitStacklen)
   
 tkWhile.genRule(parseWhile, nop, pcNone)

src/ndspkg/compiler/expressions.nim

@@ -8,8 +8,6 @@ import ../chunk
 import ../types/value
 import ../config
 
-# the following order of imports here is important
-# it defines the allowed dependency precedence between the compiler files
 import types
 import utils
 import precedence

src/ndspkg/compiler/functions.nim

@@ -6,8 +6,6 @@ import ../scanner
 import ../chunk
 import ../config
 
-# the following order of imports here is important
-# it defines the allowed dependency precedence between the compiler files
 import types
 import utils
 import precedence
@@ -19,6 +17,18 @@ proc grouping(comp: Compiler) =
   comp.expression()
   comp.consume(tkRightParen, "Expect ')' after expression.")  
 
+proc parseArgs(comp: Compiler): int =
+  var argcount = 0
+  # put args on stack
+  while comp.current.tokenType notin {tkRightParen, tkEof}:
+    comp.expression()
+    inc argcount
+    if comp.current.tokenType != tkRightParen:
+      comp.consume(tkComma, "Expected ',' between arguments in function calls.")
+  comp.consume(tkRightParen, "Expected ')' after arguments in function calls.")
+  return argcount
+
+
 proc parseCall(comp: Compiler) =
   # ( consumed
 
@@ -28,14 +38,7 @@ proc parseCall(comp: Compiler) =
   # opCall converts it to this
   # ... <ret val> <arg1> <arg2> <arg3>
 
-  var argcount = 0
-  # put args on stack
-  while comp.current.tokenType notin {tkRightParen, tkEof}:
-    comp.expression()
-    inc argcount
-    if comp.current.tokenType != tkRightParen:
-      comp.consume(tkComma, "Expected ',' between arguments in function calls.")
-  comp.consume(tkRightParen, "Expected ')' after arguments in function calls.")
+  let argcount = comp.parseArgs()
 
   # emit call
   comp.writeChunk(-argcount, opCall)
@@ -43,10 +46,32 @@ proc parseCall(comp: Compiler) =
 
 tkLeftParen.genRule(grouping, parseCall, pcCall)
 
+proc parsePipeCall(comp: Compiler) =
+  # can be followed by:
+    # idents
+    # idents+indexes
+    # NOT calls, so the parsePrecedence after it should look for pcIndex at most
+  
+  # get the function on the stack
+  comp.parsePrecedence(pcIndex)
+
+  # swap the function and the first arg
+  comp.writeChunk(0, opSwap)
+
+  var argcount = 1
+  if comp.match(tkLeftParen):
+    argcount = 1 + comp.parseArgs()
+  
+  comp.writeChunk(-argcount, opCall)
+  comp.writeChunk(0, argcount.uint8)
+
+tkDoublecolon.genRule(nop, parsePipeCall, pcAmpersand)
+
 proc parseFunct(comp: Compiler) =
 
   # jump over
-  let jumpOverBody = comp.emitJump(1, opFunctionDef)
+  var jumpStacklen = 0
+  let jumpOverBody = comp.emitJump(1, opFunctionDef, jumpStacklen)
 
   comp.consume(tkLeftParen, "Expected '(' after keyword 'funct'.")
 
@@ -89,7 +114,7 @@ proc parseFunct(comp: Compiler) =
   dec comp.stackIndex # the previous end scope did not put anything on the stack, it is jumped over
 
   # end of function declaration:
-  comp.patchJump(jumpOverBody)
+  comp.patchJump(jumpOverBody, jumpStacklen)
   # closures are implemented in a way, where the vm pops the function from the stack
   # and reads the upvalue details from the following bytes
   if f.upvalues.len() > 0:

src/ndspkg/compiler/jumps.nim

@@ -1,20 +1,24 @@
 import ../chunk
+import ../config
 
-# the following order of imports here is important
-# it defines the allowed dependency precedence between the compiler files
 import types
 import utils
 
 # JUMP HELPERS
 
-proc emitJump*(comp: Compiler, delta: int, op: OpCode): int =
+proc emitJump*(comp: Compiler, delta: int, op: OpCode, stacklen: var int): int =
   # delta -> 0 if the jump does not pop
   # delta -> -1 if the jump pops the condition from the stack
   comp.writeChunk(delta, op)
   comp.writeChunk(0, 0xffffff.toDU8)
+  when assertionsCompiler:
+    stacklen = comp.stackIndex
   comp.chunk.len - argSize
 
-proc patchJump*(comp: Compiler, offset: int) =
+proc patchJump*(comp: Compiler, offset: int, stacklen: int) =
+  when assertionsCompiler:
+    if comp.stackIndex != stacklen:
+      comp.error("Assertion failed: loop doesn't preserve stackindex.")
   let jump = (comp.chunk.len - offset - argSize)
 
   if (jump > argMax):
@@ -25,7 +29,10 @@ proc patchJump*(comp: Compiler, offset: int) =
   comp.chunk.code[offset] = jumpt[0]
   comp.chunk.code[offset + 1] = jumpt[1]
 
-proc emitLoop*(comp: Compiler, loopstart: int, delta: int, op: OpCode) =
+proc emitLoop*(comp: Compiler, loopstart: int, delta: int, op: OpCode, stacklen: int) =
+  when assertionsCompiler:
+    if comp.stackIndex != stacklen:
+      comp.error("Assertion failed: loop doesn't preserve stackindex.")
   comp.writeChunk(delta, op)
 
   let offset = comp.chunk.len - loopstart + argSize

src/ndspkg/compiler/scope.nim

@@ -6,8 +6,6 @@ import ../scanner
 import ../chunk
 import ../config
 
-# the following order of imports here is important
-# it defines the allowed dependency precedence between the compiler files
 import types
 import utils
 import jumps
@@ -65,7 +63,8 @@ proc jumpToEnd*(comp: Compiler, scope: Scope) =
   else:
     delta = comp.stackIndex - scope.goalStackIndex
   comp.writePops(delta)
-  let jmp = comp.emitJump(delta, opJump)
+  var s = 0 # discard the saved stack length
+  let jmp = comp.emitJump(delta, opJump, s)
   scope.jumps.add(jmp)
   
 proc endScope*(comp: Compiler): Scope =
@@ -94,7 +93,7 @@ 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:
-    comp.patchJump(jump)
+    comp.patchJump(jump, popped.goalStackIndex)
   if function:
     comp.writeChunk(0, opReturn)
   # remove locals from the comp object that were of this scope

src/ndspkg/compiler/statement.nim

@@ -3,8 +3,6 @@
 import ../scanner
 import ../chunk
 
-# the following order of imports here is important
-# it defines the allowed dependency precedence between the compiler files
 import types
 import utils
 import precedence

src/ndspkg/compiler/variables.nim

@@ -6,8 +6,6 @@ import ../scanner
 import ../chunk
 import ../types/value
 
-# the following order of imports here is important
-# it defines the allowed dependency precedence between the compiler files
 import types
 import utils
 import precedence
@@ -60,9 +58,10 @@ proc resolveLocal(comp: Compiler, name: string): tuple[index: int, upvalue: bool
   let cfunc: Scope = if comp.scopes.len() > 0: comp.scopes[comp.scopes.high()].parentFunction else: nil
   while i >= 0:
     let local = comp.locals[i]
+    i.dec
     if local.name == name:
       if local.depth == -1:
-        comp.error("Can't read local variable in its own initializer.")
+        continue
       let upvalue = local.scope.parentFunction != cfunc
       if not upvalue:
         return (local.index, false)
@@ -70,7 +69,6 @@ proc resolveLocal(comp: Compiler, name: string): tuple[index: int, upvalue: bool
         # resolveUpvalue
         local.captured = true
         return (comp.addUpvalue(local), true)
-    i.dec
   return (index: -1, upvalue: false)
 
 # EXPRESSIONS

src/ndspkg/scanner.nim

@@ -11,7 +11,7 @@ type
 
   TokenType* = enum
     tkNone, # the default tokentype, if encountered anywhere, erroring out is the best course of action
-    tkLeftParen, tkRightParen, tkLeftBrace, tkRightBrace, tkComma, tkDot,
+    tkLeftParen, tkRightParen, tkLeftBrace, tkRightBrace, tkComma, tkDot, tkColon, tkDoublecolon,
     tkMinus, tkPlus, tkSemicolon, tkSlash, tkStar, tkBang, tkBangEqual,
     tkGreater, tkGreaterEqual, tkLess, tkLessEqual, tkEqual, tkEqualEqual,
     tkStartList, tkStartTable, tkLeftBracket, tkRightBracket,
@@ -198,7 +198,12 @@ proc scanToken*(scanner: Scanner): Token =
       elif scanner.match('{'): return scanner.makeToken(tkStartTable)
       else: return scanner.scanLabel()
     else:
+      if c == ':' and scanner.match(':'):
+        return scanner.makeToken(tkDoublecolon)
       if c.canStartIdent():
-         return scanner.scanIdentifier()
+        # : can start ident, but if on its own it's probably syntactic sugar for tables
+        if c == ':' and not scanner.peek().canContIdent():
+          return scanner.makeToken(tkColon)
+        return scanner.scanIdentifier()
       else:
         return scanner.errorToken("Unexpected character.")

src/ndspkg/types/stack.nim

@@ -72,6 +72,15 @@ proc settip*[T](stack: var Stack[T], newtip: T)  =
       raise newException(Defect, "Stacktop is nil or smaller than start")
   stack.top[]= newtip
 
+proc swap*[T](stack: var Stack[T]) =
+  when boundsChecks:
+    if stack.top == nil or stack.len() < 2:
+      raise newException(Defect, "Stacktop is nil, or not high enough for swap.")
+  let temp = stack.top[]
+  var below = stack.top.psub(sizeof(T))
+  stack.top[] = below[]
+  below[] = temp
+
 proc deleteTopN*[T](stack: var Stack[T], n: Natural) =
   stack.top = stack.top.psub(sizeof(T) * n)
   when boundsChecks:

src/ndspkg/vm.nim

@@ -186,6 +186,8 @@ proc run*(chunk: Chunk): InterpretResult =
       of opPopSA:
         let amt = ip.readUI8()
         stack.popn(amt)
+      of opSwap:
+        stack.swap()
       of opConstant:
         let val: NdValue = ip.readConstant(chunk)
         stack.add(val)

tests/closures.nds

@@ -82,8 +82,8 @@ argcap(8.1)();
 
 // oop: constructors, getters, setters
 
-var newAnimal = funct(pspecies, color) {
-  var species = pspecies; // copy it so that it's mutable, if args ever get immutable
+var newAnimal = funct(species, color) {
+  var species = species; // copy it so that it's mutable, if args ever get immutable
   var animal = @{
     "getSpecies" = funct() :result = species,
     "setSpecies" = funct(newSpecies) species = newSpecies,

tests/math.nds

@@ -0,0 +1,8 @@
+print (0/0 == 0/0);
+//expect:false
+
+print (1/0 == 3/0);
+//expect:true
+
+print (1/0 == -2/0);
+//expect:false

tests/sugar.nds

@@ -0,0 +1,43 @@
+// testing syntactic sugars
+
+// :: piping function call
+
+var double = funct(num) :result = num * 2;
+
+var four = 2 :: double();
+
+var multiply = funct(num, factor) :result = num * factor;
+
+var six = 2 :: multiply(3);
+
+print (four);
+print (six);
+//expect:4.0
+//expect:6.0
+
+print (1 + 2 * 3 :: tostring() + "2");
+//expect:7.02
+
+// indexing tables with .
+
+var nested = @{
+  "lvl1" = @{
+    "lvl2" = @{
+      "lvl3" = 5
+    }
+  }
+};
+
+nested.lvl1.lvl2.lvl3 = 6;
+print(nested.lvl1.lvl2.lvl3);
+//expect:6.0
+
+nested["lvl1"].lvl2["lvl3"] = 2;
+print(nested.lvl1["lvl2"].lvl3);
+//expect:2.0
+
+nested["lvl1"]["lvl2"]["lvl3"] = -5.4;
+nested .lvl1 .lvl2 .lvl3 :: print;
+//expect:-5.4
+
+// creating tables with : and no [] idents