RECUR keyword added
This commit is contained in:
Michael Schimmel
+59
-90
@@ -21,9 +21,6 @@ uses
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FMX.ScrollBox,
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FMX.Memo,
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FMX.Controls.Presentation,
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Myc.Fmx.AstEditor,
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Myc.Fmx.AstEditor.Node,
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Myc.Fmx.AstEditor.Workspace,
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Myc.Data.Scalar,
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Myc.Data.Value,
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Myc.Ast.Nodes,
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@@ -36,7 +33,10 @@ uses
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Myc.Ast.RTL,
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FMX.Layouts,
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FMX.Objects,
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Myc.Ast.Debugger;
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Myc.Ast.Debugger,
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Myc.Fmx.AstEditor,
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Myc.Fmx.AstEditor.Node,
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Myc.Fmx.AstEditor.Workspace;
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type
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// A test record
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@@ -281,31 +281,42 @@ var
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sw: TStopwatch;
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begin
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// Create a setup script to define a memoize-compatible 'fib' function globally.
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// This is rewritten to be tail-recursive using the 'recur' keyword.
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var fibAst :=
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TAst.Block(
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[
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// 1. var fib; (Declare the name so it can be captured by the lambda. Initializer is nil)
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// 1. var fib_iter = lambda(n, a, b) { ... }; (The tail-recursive part)
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TAst.VarDecl(
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TAst.Identifier('fib_iter'),
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TAst.LambdaExpr(
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[TAst.Identifier('n'), TAst.Identifier('a'), TAst.Identifier('b')],
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TAst.TernaryExpr(
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TAst.BinaryExpr(TAst.Identifier('n'), boEqual, TAst.Constant(TScalar.FromInt64(0))),
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TAst.Identifier('a'), // Base case 1
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TAst.TernaryExpr(
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TAst.BinaryExpr(TAst.Identifier('n'), boEqual, TAst.Constant(TScalar.FromInt64(1))),
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TAst.Identifier('b'), // Base case 2
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TAst.Recur( // Tail-recursive step
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[
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TAst.BinaryExpr(TAst.Identifier('n'), boSubtract, TAst.Constant(TScalar.FromInt64(1))),
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TAst.Identifier('b'),
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TAst.BinaryExpr(TAst.Identifier('a'), boAdd, TAst.Identifier('b'))
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]
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)
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)
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)
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)
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),
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// 2. var fib;
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TAst.VarDecl(TAst.Identifier('fib')),
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// 2. var fib_impl = lambda(n) { ... fib(n-1) + fib(n-2) ... };
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// 3. fib = lambda(n) { fib_iter(n, 0, 1) }; (The public-facing function)
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TAst.Assign(
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TAst.Identifier('fib'),
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TAst.LambdaExpr(
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[TAst.Identifier('n')],
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TAst.TernaryExpr(
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TAst.BinaryExpr(TAst.Identifier('n'), boLess, TAst.Constant(TScalar.FromInt64(2))),
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TAst.Identifier('n'),
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TAst.BinaryExpr(
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// Recursive calls now use the re-bindable name 'fib' instead of 'Self'
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TAst.FunctionCall(
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TAst.Identifier('Self'),
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[TAst.BinaryExpr(TAst.Identifier('n'), boSubtract, TAst.Constant(TScalar.FromInt64(1)))]
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),
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boAdd,
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TAst.FunctionCall(
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TAst.Identifier('Self'),
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[TAst.BinaryExpr(TAst.Identifier('n'), boSubtract, TAst.Constant(TScalar.FromInt64(2)))]
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)
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)
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TAst.FunctionCall(
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TAst.Identifier('fib_iter'),
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[TAst.Identifier('n'), TAst.Constant(TScalar.FromInt64(0)), TAst.Constant(TScalar.FromInt64(1))]
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)
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)
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)
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@@ -314,10 +325,10 @@ begin
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var fibScope := TAstBinder.Bind(fibAst, FGScope).CreateScope(FGScope);
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var visitor := CreateVisitor(fibScope);
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Result := visitor.Execute(fibAst);
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visitor.Execute(fibAst);
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Memo1.Lines.Clear;
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Memo1.Lines.Add('--- Recursive fib with AST---');
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Memo1.Lines.Add('--- Tail-Recursive fib with AST---');
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sw := TStopwatch.StartNew;
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root := TAst.FunctionCall(TAst.Identifier('fib'), [TAst.Constant(TScalar.FromInt64(30))]);
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@@ -330,7 +341,7 @@ begin
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Memo1.Lines.Add(Format('Result: fib(30) %s (calculated in %d ms)', [result.ToString, sw.ElapsedMilliseconds]));
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Memo1.Lines.Add('');
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Memo1.Lines.Add('--- Memoized recursive fib with AST (using global fib)---');
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Memo1.Lines.Add('--- Memoized tail-recursive fib with AST (using global fib)---');
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sw := TStopwatch.StartNew;
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root :=
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@@ -375,30 +386,39 @@ var
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sw: TStopwatch;
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begin
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Memo1.Lines.Clear;
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Memo1.Lines.Add('--- Recursive factorial(20) ---');
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Memo1.Lines.Add('--- Tail-Recursive factorial(20) ---');
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sw := TStopwatch.StartNew;
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// Rewritten to be tail-recursive to use 'recur'
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root :=
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TAst.Block(
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[
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// Define the tail-recursive helper function
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TAst.VarDecl(
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TAst.Identifier('factorial'),
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TAst.Identifier('fact_iter'),
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TAst.LambdaExpr(
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[TAst.Identifier('n')],
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[TAst.Identifier('n'), TAst.Identifier('acc')],
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TAst.TernaryExpr(
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TAst.BinaryExpr(TAst.Identifier('n'), boLess, TAst.Constant(TScalar.FromInt64(2))),
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TAst.Constant(TScalar.FromInt64(1)),
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TAst.BinaryExpr(
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TAst.Identifier('n'),
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boMultiply,
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TAst.FunctionCall(
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TAst.Identifier('Self'),
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[TAst.BinaryExpr(TAst.Identifier('n'), boSubtract, TAst.Constant(TScalar.FromInt64(1)))]
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)
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TAst.BinaryExpr(TAst.Identifier('n'), boLessOrEqual, TAst.Constant(TScalar.FromInt64(1))),
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TAst.Identifier('acc'), // Base case: return the accumulator
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TAst.Recur( // Tail-recursive step
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[
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TAst.BinaryExpr(TAst.Identifier('n'), boSubtract, TAst.Constant(TScalar.FromInt64(1))),
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TAst.BinaryExpr(TAst.Identifier('acc'), boMultiply, TAst.Identifier('n'))
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]
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)
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)
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)
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),
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// Define the public-facing factorial function
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TAst.VarDecl(
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TAst.Identifier('factorial'),
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TAst.LambdaExpr(
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[TAst.Identifier('n')],
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TAst.FunctionCall(TAst.Identifier('fact_iter'), [TAst.Identifier('n'), TAst.Constant(TScalar.FromInt64(1))])
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)
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),
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// Call the main function
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TAst.FunctionCall(TAst.Identifier('factorial'), [TAst.Constant(TScalar.FromInt64(20))])
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]
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);
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@@ -566,54 +586,6 @@ begin
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var setupAst :=
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TAst.Block(
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[
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// TAst.VarDecl(
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// TAst.Identifier('CreateSMA'),
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// TAst.LambdaExpr(
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// [TAst.Identifier('len')],
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// TAst.Block(
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// [
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// TAst.VarDecl(TAst.Identifier('sum'), TAst.Constant(TScalar.FromDouble(0.0))),
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// TAst.VarDecl(TAst.Identifier('count'), TAst.Constant(TScalar.FromInt64(0))),
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// TAst.LambdaExpr(
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// [TAst.Identifier('series'), TAst.Identifier('val')],
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// TAst.Block(
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// [
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// TAst.Assign(
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// TAst.Identifier('sum'),
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// TAst.BinaryExpr(TAst.Identifier('sum'), boAdd, TAst.Identifier('val'))
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// ),
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// TAst.Assign(
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// TAst.Identifier('count'),
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// TAst.BinaryExpr(TAst.Identifier('count'), boAdd, TAst.Constant(TScalar.FromInt64(1)))
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// ),
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// TAst.IfExpr(
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// TAst.BinaryExpr(TAst.Identifier('count'), boGreater, TAst.Identifier('len')),
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// TAst.Assign(
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// TAst.Identifier('sum'),
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// TAst.BinaryExpr(
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// TAst.Identifier('sum'),
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// boSubtract,
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// TAst.Indexer(TAst.Identifier('series'), TAst.Identifier('len'))
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// )
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// ),
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// nil
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// ),
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// TAst.BinaryExpr(
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// TAst.Identifier('sum'),
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// boDivide,
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// TAst.TernaryExpr(
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// TAst.BinaryExpr(TAst.Identifier('count'), boLess, TAst.Identifier('len')),
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// TAst.Identifier('count'),
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// TAst.Identifier('len')
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// )
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// )
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// ]
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// )
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// )
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// ]
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// )
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// )
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// ),
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TAst.VarDecl(
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TAst.Identifier('smaFast'),
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TAst.FunctionCall(TAst.Identifier('CreateSMA'), [TAst.Constant(TScalar.FromInt64(smaFastLength))])
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@@ -961,14 +933,11 @@ begin
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TAst.Identifier('countDown'),
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TAst.LambdaExpr(
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[TAst.Identifier('n')],
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// if (n > 0) then Self(n-1) else 'done'
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// if (n > 0) then recur(n-1) else 'done'
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TAst.IfExpr(
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TAst.BinaryExpr(TAst.Identifier('n'), boGreater, TAst.Constant(TScalar.FromInt64(0))),
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// This is the tail call position.
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TAst.FunctionCall(
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TAst.Identifier('Self'),
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[TAst.BinaryExpr(TAst.Identifier('n'), boSubtract, TAst.Constant(TScalar.FromInt64(1)))]
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),
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// This is the tail call position, now using recur.
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TAst.Recur([TAst.BinaryExpr(TAst.Identifier('n'), boSubtract, TAst.Constant(TScalar.FromInt64(1)))]),
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// Base case of the recursion
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TAst.Constant(TScalar.FromString('done'))
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)
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