chapter A self-hosting (wip)

Author: metaleap

hello.lisp

@@ -0,0 +1,14 @@
+; run with: `rlwrap go run *.go hello.lisp` or `rlwrap go run *.go hello.lisp World`
+
+(def greet
+    (fn (name)
+        (def repeat (not (bool name)))
+        (set name (or name (readLine "Name: ")))
+        (if (= "" name)
+            (set repeat :false)
+            (println "Hello, " name "!"))
+        (if repeat (greet :nil) :nil)))
+
+(if (isEmpty osArgs)
+    (greet :nil)
+    (map greet osArgs))

interp.go

@@ -5,10 +5,10 @@ import (
 	"fmt"
 )
 
-const disableTracing = true
-const disableTcoFuncs = false // caution: cannot def `macro`s if `true`; setting is just for quick temporary via-REPL trouble-shootings to see if TCO got somehow broken.
+const disableTcoFuncs = false // caution: if `true`, cannot def `macro`s; this bool is just for quick temporary via-REPL trouble-shootings to see if TCO got somehow broken (or to enable call tracing for trouble-shooting)
+const disableTracing = true || !disableTcoFuncs
 
-// to confirm TCO still works, uncomment the 2 commented lines in `evalAndApply` below.
+// to confirm TCO still works, uncomment the 2 commented lines in `evalAndApply` below that are referring to `id`.
 // another way: run `(sum2 10000000 0)` with TCO disabled (stack overflow) and then re-enabled (no stack overflow), where `sum2` is in github.com/kanaka/mal/blob/master/impls/tests/step5_tco.mal
 
 func evalAndApply(env *Env, expr Expr) (Expr, error) {

main.go

@@ -114,7 +114,7 @@ const srcMiniStdlibMacros = `
 
 (def or
 	(macro (any1 any2)
-		´(if ~any1 :true ~any2)))
+		´(if ~any1 ~any1 ~any2)))
 
 (def postfix ;;; turns (1 2 +) into (+ 1 2)
 	(macro (call)

std.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"errors"
 	"fmt"
 	"io"
 	"os"
@@ -57,6 +58,9 @@ var (
 		"quit":         ExprFunc(stdQuit),
 		"exit":         ExprFunc(stdQuit),
 		"time-ms":      ExprFunc(stdTimeMs),
+		"bool":         ExprFunc(stdBool),
+		"seq":          ExprFunc(stdSeq),
+		"conj":         ExprFunc(stdConj),
 	}}
 )
 
@@ -205,12 +209,22 @@ func stdIs(args []Expr) (Expr, error) {
 		if _, ok = args[1].(*ExprFn); !ok {
 			_, ok = args[1].(ExprFunc)
 		}
+	case ":macro":
+		if fn, _ := args[1].(*ExprFn); fn != nil {
+			ok = fn.isMacro
+		}
 	case ":err":
 		_, ok = args[1].(ExprErr)
 	case ":atom":
 		_, ok = args[1].(*ExprAtom)
+	case ":nil":
+		ok = (isEq(exprNil, args[1]))
+	case ":true":
+		ok = (isEq(exprTrue, args[1]))
+	case ":false":
+		ok = (isEq(exprFalse, args[1]))
 	default:
-		return nil, fmt.Errorf("expected not `%s` but one of: `:list`, `:ident`, `:str`, `:num`, `:vec`, `:hashmap`, `:fn`, `:keyword`, `:atom`, `:err`", kind)
+		return nil, fmt.Errorf("expected not `%s` but one of: `:list`, `:ident`, `:str`, `:num`, `:vec`, `:hashmap`, `:fn`, `:macro`, `:keyword`, `:atom`, `:err`, `:nil`, `:true`, `:false`", kind)
 	}
 	return exprBool(ok), nil
 }
@@ -662,3 +676,46 @@ func stdQuit(args []Expr) (Expr, error) {
 func stdTimeMs(args []Expr) (Expr, error) {
 	return ExprNum(time.Now().UnixMilli()), nil
 }
+
+func stdBool(args []Expr) (Expr, error) {
+	if err := checkArgsCount(1, 1, args); err != nil {
+		return nil, err
+	}
+	return exprBool((!isEq(exprFalse, args[0])) && !isEq(exprNil, args[0])), nil
+}
+
+func stdSeq(args []Expr) (Expr, error) {
+	if err := checkArgsCount(1, 1, args); err != nil {
+		return nil, err
+	}
+	if isEq(exprNil, args[0]) {
+		return args[0], nil
+	}
+	switch it := args[0].(type) {
+	case ExprList:
+		if len(it) == 0 {
+			return exprNil, nil
+		}
+		return it, nil
+	case ExprVec:
+		if len(it) == 0 {
+			return exprNil, nil
+		}
+		return (ExprList)(it), nil
+	case ExprStr:
+		if len(it) == 0 {
+			return exprNil, nil
+		}
+		expr := make(ExprList, 0, len(it))
+		for _, char := range it {
+			expr = append(expr, ExprStr(char))
+		}
+		return expr, nil
+	}
+
+	return nil, fmt.Errorf("expected a list, vector, string or :nil instead of `%s`", str(true, args[0]))
+}
+
+func stdConj(args []Expr) (Expr, error) {
+	return nil, errors.New("TODO")
+}