chapter 9: cleanups

Author: metaleap

ast.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"cmp"
-	"errors"
 	"fmt"
 	"reflect"
 	"strings"
@@ -160,25 +159,6 @@ func isEq(arg1 Expr, arg2 Expr) bool {
 	}
 }
 
-func newHashMap(seq Expr) (Expr, error) {
-	list, err := checkIsSeq(seq)
-	if err != nil {
-		return nil, err
-	}
-	if (len(list) % 2) != 0 {
-		return nil, errors.New("odd number of arguments to NewHashMap")
-	}
-	hash_map := ExprHashMap{}
-	for i := 1; i < len(list); i += 2 {
-		str, ok := list[i-1].(ExprStr)
-		if !ok {
-			return nil, errors.New("expected hash-map key string")
-		}
-		hash_map[str] = list[i]
-	}
-	return hash_map, nil
-}
-
 func str(srcLike bool, args ...Expr) string {
 	var buf strings.Builder
 	for i, arg := range args {

reader.go

@@ -80,8 +80,7 @@ func readList(r Reader, start string, end string) (Expr, error) {
 	}
 
 	var ast_list ExprList
-	token = r.peek()
-	for ; true; token = r.peek() {
+	for token = r.peek(); true; token = r.peek() {
 		if token == nil {
 			return nil, errors.New("expected '" + end + "', got EOF")
 		}
@@ -103,16 +102,15 @@ func readVec(r Reader) (Expr, error) {
 	if err != nil {
 		return nil, err
 	}
-	vec := ExprVec(list.(ExprList))
-	return vec, nil
+	return ExprVec(list.(ExprList)), nil
 }
 
 func readHashMap(r Reader) (Expr, error) {
 	list, err := readList(r, "{", "}")
 	if err != nil {
 		return nil, err
 	}
-	return newHashMap(list)
+	return stdHashmap(list.(ExprList))
 }
 
 func readForm(r Reader) (Expr, error) {

special_forms.go

@@ -255,9 +255,12 @@ func stdQuasiQuote(env *Env, args []Expr) (*Env, Expr, error) {
 }
 
 func stdTryCatch(env *Env, args []Expr) (*Env, Expr, error) {
-	if err := checkArgsCount(2, 2, args); err != nil {
+	if err := checkArgsCount(1, 2, args); err != nil {
 		return nil, nil, err
 	}
+	if len(args) == 1 {
+		return env, args[0], nil
+	}
 
 	catch, ok, err := isListStartingWithIdent(args[1], "catch", 3)
 	if err != nil {

std.go

@@ -543,7 +543,7 @@ func stdHashmapDel(args []Expr) (Expr, error) {
 
 	new_hashmap := make(ExprHashMap, len(hashmap)-len(keys_to_delete))
 	for k, v := range hashmap {
-		if !slices.ContainsFunc(keys_to_delete, func(it Expr) bool { return it.(ExprIdent) == ExprIdent(k) }) {
+		if !slices.ContainsFunc(keys_to_delete, func(it Expr) bool { return it.(ExprStr) == ExprStr(k) }) {
 			new_hashmap[k] = v
 		}
 	}