Nested functions & "is not" operator

Author: slackydev

README.md

@@ -4,18 +4,8 @@
 It features a Pascal-inspired syntax, iwth features taken from a number of newer languages. 
 
 The aim is a programming language that will be a direct conduit from a developer's mind to the machine, 
-not a maze of mandatory abstractions, unsafe patterns, or verbose boilerplate.
+not a maze of mandatory abstractions, or symbolic verbose boilerplate.
 
-The philosophy is simple:
-
-- Pragmatic: Express inherits the strong safety guarantees of Pascal but sheds its verbosity. 
-  It offers the low-level, but unlike C-family languages it's cleaner, less symbol-heavy syntax. 
-  The result is a language that feels intuitive and modern, choosing proven concepts over novelty.
-- Clear by design: The syntax is minimal and consistent. There is no hidden "fallthrough" in switch statements and no mandatory semicolons. Type inference, lightweight record types, and universal extension methods reduce boilerplate and allow the code to clearly express the programmer's intent.
-- Write Fast, Refine for Safety. Express is designed to support a rapid development workflow. The principle is simplicity first; safety is a tool for refinement, not a barrier to entry.
-  You can declare variables with type inference (var x := 10) to get your ideas working quickly. Later, you can add explicit types (var x: Int64 = 10) to make the code more robust.
-  Similarly, method overrides are implicit by default, simplifying OOP. In the future, an optional `@override` attribute will allow you to ask the compiler to verify that you are correctly overriding a parent method, adding a layer of safety when you need it.
-  This "progressive enhancement" approach is central to the language, a language that lets you write code quickly, and then helps you make it correct.
 
 ---
 
@@ -231,7 +221,6 @@ Enums and Sets: For more expressive and safe code.
 
 - Operator Overloading: Allowing user-defined types to work with standard operators.
 - Properties: Class and record fields with custom getter/setter logic.
-- Nested Functions: To enable more powerful functional patterns.
 - Default function parameters with assign by name
 - Strings are currently limited to Ansistring.
 

compiler/xpr.compilercontext.pas

@@ -63,7 +63,13 @@   TXprVar = record // might be best to make this a class, records are clumpsy he
     function InCurrentScope(ctx: TCompilerContext): Boolean;
   end;
 
+  TNamedVar = record
+    Name: string;
+    XprVar: TXprVar;
+  end;
+
   TXprVarList = specialize TArrayList<TXprVar>;
+  TVarList    = specialize TArrayList<TNamedVar>;
   TStringToObject = specialize TDictionary<string, XType>;
   TXprTypeList = specialize TArrayList<XType>;
 
@@ -248,6 +254,8 @@   TCompilerContext = class(TObject)
     function EmitUpcastIfNeeded(VarToCast: TXprVar; TargetType: XType; DerefIfUpcast:Boolean): TXprVar;
     procedure VarToDefault(TargetVar: TXprVar);
     function GetManagedDeclarations(): TXprVarList;
+    function GetClosureVariables(): TVarList;
+
     function GenerateIntrinsics(Name: string; Arguments: array of XType; SelfType: XType; CompileAs: string = ''): XTree_Node;
     function ResolveMethod(Name: string; Arguments: XTypeArray; SelfType, RetType: XType; DocPos:TDocPos): TXprVar;
     procedure ResolveToFinalType(var PseudoType: XType);
@@ -560,7 +568,7 @@ procedure TCompilerContext.DecScope();
 
 function TCompilerContext.GetStackPos(): SizeInt;
 begin
-  Result := StackPosArr[Scope]{+SizeOf(Pointer)};
+  Result := StackPosArr[Scope];
 end;
 
 procedure TCompilerContext.IncStackPos(Size:Int32=STACK_ITEM_ALIGN);
@@ -697,6 +705,10 @@ function TCompilerContext.GetVar(Name: string; Pos:TDocPos): TXprVar;
   // Search scopes from the inside out (current scope -> parent -> ... -> global)
   for i := Self.Scope downto GLOBAL_SCOPE do
   begin
+    // XXX: new design, only do local and global here
+    if (i <> self.Scope) and (i <> GLOBAL_SCOPE) then
+      continue;
+
     // prefer local w/ namespace
     if CurrentNamespace <> '' then
     begin
@@ -984,7 +996,7 @@ function TCompilerContext.RegVar(Name: string; var Value: TXprVar; DocPos: TDocP
 
   exists := self.VarDecl[varScope].Get(XprCase(PrefixedName), declList);
   if exists then
-  begin
+  begin          //XXX: Make it all just Add - verify integrity of it
     if (Value.VarType.BaseType in [xtMethod, xtExternalMethod]) then
       declList.Add(Result)
     else
@@ -1026,7 +1038,7 @@ function TCompilerContext.RegGlobalVar(Name: string; var Value: TXprVar; DocPos:
 
 function TCompilerContext.RegMethod(Name: string; var Value: TXprVar; DocPos: TDocPos): Int32;
 begin
-  Result   := Self.RegVar(XprCase(Name), Value, DocPos, True);
+  Result := Self.RegVar(XprCase(Name), Value, DocPos, True);
 end;
 
 
@@ -1381,6 +1393,27 @@ function TCompilerContext.GetManagedDeclarations(): TXprVarList;
         end;
 end;
 
+function TCompilerContext.GetClosureVariables(): TVarList;
+var
+  i,j,k: Int32;
+  xprVar: TNamedVar;
+begin
+  Result.Init([]);
+  // looks crazy, but it's not that bad
+
+  with Self.VarDecl[scope] do
+    for i:=0 to RealSize-1 do
+      for j:=0 to High(Items[i]) do
+      begin
+        k := Items[i][j].val.High();
+        if k < 0 then continue;
+
+        xprVar.XprVar := Self.Variables.Data[Items[i][j].val.data[k]];
+        xprVar.Name   := Items[i][j].key;
+        Result.Add(xprVar);
+      end;
+end;
+
 
 
 function GetConversionCost(FromType, ToType: XType): Integer;
@@ -1520,13 +1553,14 @@ function TCompilerContext.ResolveMethod(Name: string; Arguments: XTypeArray; Sel
     Ambiguous := False;
     for i := 0 to CandidateList.High do
     begin
+      if name = 'recurse' then  WriteLn(Name,': ',CandidateList.Data[i].NestingLevel);
+
       CandidateVar := CandidateList.Data[i];
       if not (CandidateVar.VarType is XType_Method) then Continue;
       FType := XType_Method(CandidateVar.VarType);
 
       if (SelfType <> nil) and not FType.TypeMethod then Continue;
-      if Length(FType.Params) <> Length(EffectiveArgs) then Continue;
-
+      if FType.RealParamcount <> Length(EffectiveArgs) then Continue;
       TotalScore := (CandidateVar.NestingLevel * SCOPE_PENALTY);
 
 
@@ -1602,6 +1636,7 @@ function TCompilerContext.ResolveMethod(Name: string; Arguments: XTypeArray; Sel
   CURRENT_SCOPE: Int32;
 begin
   Result := Resolve(Self.GetVarList(Name));
+  if name = 'recurse' then WriteLn(Name,': ',Result.NestingLevel);
 
   if (Result = NullVar) then
   begin
@@ -1855,6 +1890,7 @@ function XType.Equals(Other: XType): Boolean;
 
 function XType.IsManagedType(ctx: TCompilerContext): Boolean;
 begin
+  Assert(Self <> nil, 'It should be impossible');
   Result := ((Self.BaseType in XprRefcountedTypes)) or
             ((Self is XType_Record) and ctx.IsManagedRecord(Self));
 end;

compiler/xpr.interpreter.pas

@@ -804,16 +804,6 @@ procedure TInterpreter.Run(var BC: TBytecode);
         bcCOPY_GLOBAL:
           Pointer(Pointer(BasePtr + pc^.Args[0].Data.Addr)^) := Pointer(Global(pc^.Args[1].Data.Addr)^);
 
-        bcLOAD_NONLOCAL: //static link walk
-          begin
-            raise Exception.Create('NONLOCAL: NOT IMPLEMENTED');
-            //ParentFramePtr := PPointer(BasePtr + SizeOf(Pointer))^; //statick link is stored here
-            //for linkwalk := 1 to pc^.Args[3].Data.i32 - 1 do
-            //  ParentFramePtr := Pointer(Pointer(ParentFramePtr + SizeOf(Pointer))^);
-
-            //Pointer(Pointer(BasePtr + pc^.Args[0].Data.Addr)^) := Pointer(ParentFramePtr + pc^.Args[1].Data.Addr);
-          end;
-
         bcNEWFRAME:
           begin
             // This might save us from a lot of bullshit:

compiler/xpr.langdef.pas

@@ -22,7 +22,7 @@   TOperatorDef = record
   end;
 
 const
-  BinPrecedence: array [0..36] of TOperatorDef = (
+  BinPrecedence: array [0..37] of TOperatorDef = (
     // Level 0: Assignments
     (OP:tkASGN;       Prec:0;   Assoc:-1),
     (OP:tkPLUS_ASGN;  Prec:0;   Assoc:-1),
@@ -47,6 +47,7 @@   TOperatorDef = record
     (OP:tkEQ;         Prec:5;   Assoc:1),
     (OP:tkNE;         Prec:5;   Assoc:1),
     (OP:tkKW_IS;      Prec:5;   Assoc:1),
+    (OP:tkKW_ISNOT;   Prec:5;   Assoc:1),
 
     // Level 6: Relational Operators
     (OP:tkLT;         Prec:6;   Assoc:1),

compiler/xpr.parser.pas

@@ -1371,6 +1371,11 @@ function TParser.RHSExpr(Left:XTree_Node; leftPrecedence:Int8=0): XTree_Node;
       Result := XTree_DynCast.Create(Left, Right, FContext, DocPos)
     else if (OP = op_IS) and (Right is XTree_Identifier) then
       Result := XTree_TypeIs.Create(Left, Right, FContext, DocPos)
+    else if (OP = op_ISNOT) and (Right is XTree_Identifier) then
+    begin
+      WriteLn('ISNOT');
+      Result := XTree_UnaryOp.Create(op_not, XTree_TypeIs.Create(Left, Right, FContext, DocPos), FContext, DocPos)
+    end
     else
       Result := XTree_BinaryOp.Create(op, Left, Right, FContext, DocPos);
   end;

compiler/xpr.tokenizer.pas

@@ -40,6 +40,7 @@ interface
     tkKW_IN,
     tkKW_INHERITED,
     tkKW_IS,
+    tkKW_ISNOT,
     tkKW_NEW,
     tkKW_NIL,
     tkKW_OF,
@@ -241,6 +242,7 @@ function isNoDocPos(Pos: TDocPos): Boolean; inline;
     'in',
     'inherited',
     'is',
+    'is not',
     'new',
     'nil',
     'of',
@@ -400,7 +402,13 @@ procedure TTokenizer.AddIdent();
   while Current in ['a'..'z','A'..'Z','_','0'..'9'] do Inc(pos);
   tmp := Copy(data, i, pos-i);
   tok := KeywordMap.GetDef(XprCase(tmp), tkIdent);
-  self.Append(tok, tmp);
+
+  if (FArrHigh > 0) and (tok = tkNOT) and (self.Tokens[FArrHigh-1].Token = tkKW_IS) then
+  begin
+    self.Tokens[FArrHigh-1].Token := tkKW_ISNOT;
+    self.Tokens[FArrHigh-1].Value := 'is not';
+  end else
+    self.Append(tok, tmp);
 end;