From cc6c9ed98b37967fe03319b6e2974896312888b8 Mon Sep 17 00:00:00 2001
From: yoyo <ghwns674@gmail.com>
Date: Wed, 11 Sep 2024 13:44:56 +0900
Subject: [PATCH] add fnlet

---
 bltin.c |  3 +++
 dat.h   |  1 +
 eval.c  | 35 +++++++++++++++++++++++++----------
 obj.c   |  2 +-
 4 files changed, 30 insertions(+), 11 deletions(-)

diff --git a/bltin.c b/bltin.c
index 09c7e95..1d3a086 100644
--- a/bltin.c
+++ b/bltin.c
@@ -20,6 +20,7 @@ Object Not	= (Object){.type=OBLTIN, .beg= "not"};
 
 Object Bquote= (Object){.type=OBLTIN, .beg="`"};
 Object Lambda= (Object){.type=OBLTIN, .beg="lambda"};
+Object Let= (Object){.type=OBLTIN, .beg="let"};
 Object Progn=(Object){.type=OBLTIN, .beg="progn"};
 Object Car	= (Object){.type=OBLTIN, .beg="car"};
 Object Cdr	= (Object){.type=OBLTIN, .beg="cdr"};
@@ -35,6 +36,7 @@ extern Object* fnmul(Object *, Object *);
 extern Object* fndiv(Object *, Object *);
 extern Object* fnmod(Object *, Object *);
 extern Object* fnlambda(Object *, Object *);
+extern Object* fnlet(Object *, Object *);
 extern Object* fnprogn(Object *, Object *);
 extern Object* fndefine(Object *, Object *);
 extern Object* fnmacro(Object *, Object *);
@@ -72,6 +74,7 @@ bltinlookup(Object *obj)
 		{&Define ,fndefine},
 		{&Macro ,fnmacro},
 		{&Setq ,fnsetq},
+		{&Let ,fnlet},
 		{&Quote ,fnquote},
 		{&Bquote,  fnbquote},
 		{&Car ,fncar},
diff --git a/dat.h b/dat.h
index c661949..cfd3dc2 100644
--- a/dat.h
+++ b/dat.h
@@ -69,6 +69,7 @@ extern Object Define;
 extern Object Progn;
 extern Object Macro;
 extern Object Setq;
+extern Object Let;
 extern Object Eq;
 extern Object Not;
 extern Object Ne;
diff --git a/eval.c b/eval.c
index 5ebb5ba..8a819f6 100644
--- a/eval.c
+++ b/eval.c
@@ -130,26 +130,41 @@ fnprogn(Object *env, Object *list)
 Object*
 fnsetq(Object *env, Object *list)
 {
-	if(exprlen(list)!=2 || list->car->type!=OIDENT)
+	if(list->type != OCELL || exprlen(list)!=2 || list->car->type!=OIDENT)
 		error("Malformed setq");
 	Object *cur = env;
-	Object *p = 0;
+	Object *p = &Nil;
 	for(; cur!=&Nil; cur=cur->up)
-	for(p=cur->vars; p!=&Nil; p=p->cdr)
-		if(strequal(list->car, p->car->car))
-				goto found;
+	for(p=cur->vars; p!=&Nil; p=cdr(p))
+		if(strequal(list->car, car(car(p))))
+			return p->car->cdr = eval(env, car(cdr(list)));	
 	error("setq not exist variable");
-found:;
-	return p->car->cdr = eval(env, list->cdr->car);	
+	return 0;
+}
+
+Object*
+fnlet(Object *env, Object *list)
+{
+	if(exprlen(list) < 2)
+		error("let (vars) bodys");
+	Object *nenv = newenv(gc, &Nil, &Nil, env) ;
+	for(Object *p=list->car; p!=&Nil; p=cdr(p)){
+		Object *var = car(car(p));
+		if(var->type != OIDENT)
+			error("expected ident");
+		Object *val = eval(env, car(cdr(car(p))));
+		nenv->vars = newacons(gc, var, val, nenv->vars);
+	}
+	return progn(nenv, cdr(list));
 }
 
 Object*
 fndefine(Object *env, Object *list)
 {
-	if(exprlen(list)!=2 || list->car->type!=OIDENT)
+	if(exprlen(list)!=2 || car(list)->type!=OIDENT)
 		error("Malformed define");
-	Object *val = eval(env, list->cdr->car);
-	env->vars = defvar(env, list->car, val);
+	Object *val = eval(env, car(cdr(list)));
+	env->vars = defvar(env, car(list), val);
 	return val;
 }
 
diff --git a/obj.c b/obj.c
index 15e1627..8e1213e 100644
--- a/obj.c
+++ b/obj.c
@@ -63,7 +63,7 @@ newsymbol(GC *gc, char *str, int len)
 		&Nil,  &Minus, &Plus, &Mul, &Mod, &Div, &Ge, &Le,
 		&Lt, &Gt, &Ne, &Lambda, &Car, &Cdr, &Quote, &Cons,
 		&Define, &Setq, &Eq, &If, &Macro, &Progn, &Bquote,
-		&Comma, &Not, &Splice,
+		&Comma, &Not, &Splice, &Let,
 	};
 	for(int i = 0; i < sizeof(syms)/sizeof(syms[0]); ++i){
 		Object *c = syms[i];