add '`', '\''

bltin.c

@@ -15,6 +15,8 @@ Object Gt	= (Object){.type=OBLTIN, .beg= ">"};
 Object Ne	= (Object){.type=OBLTIN, .beg= "!="};
 Object Eq	= (Object){.type=OBLTIN, .beg= "=="};
 
+Object Comma= (Object){.type=OBLTIN, .beg=","};
+Object Bquote= (Object){.type=OBLTIN, .beg="`"};
 Object Lambda= (Object){.type=OBLTIN, .beg="lambda"};
 Object Progn=(Object){.type=OBLTIN, .beg="progn"};
 Object Car	= (Object){.type=OBLTIN, .beg="car"};
@@ -39,6 +41,7 @@ extern Object* fndefn(Object *, Object *);
 extern Object* fnsetq(Object *, Object *);
 extern Object* fnundef(Object *, Object *);
 extern Object* fnquote(Object *, Object *);
+extern Object* fnbquote(Object *, Object *);
 extern Object* fncar(Object *, Object *);
 extern Object* fncdr(Object *, Object *);
 extern Object* fncons(Object *, Object *);
@@ -70,6 +73,7 @@ bltinlookup(Object *obj)
 		{&Defn ,fndefn},
 		{&Setq ,fnsetq},
 		{&Quote ,fnquote},
+		{&Bquote,  fnbquote},
 		{&Car ,fncar},
 		{&Cdr ,fncdr},
 		{&Cons ,fncons},

dat.h

@@ -11,7 +11,6 @@ enum OType
 	OIDENT,
 	OSTRING,
 	OINT,
-	OLAMBDA,
 	OFUNC,
 	OMACRO,
 	OENV,
@@ -53,6 +52,8 @@ struct Object
 
 extern GC *gc;
 extern Object Nil;
+extern Object Comma;
+extern Object Bquote;
 extern Object Minus;
 extern Object Plus;
 extern Object Mul;

eval.c

@@ -123,6 +123,37 @@ fnquote(Object *env, Object *list)
     return list->car;
 }
 
+static Object*
+evalcomma(Object *env, Object *p)
+{
+	enum { VISITED = 1 << 9 };
+
+	if(p->type == OCELL){
+		if(p->flag & VISITED)
+			return p;
+		p->flag |= VISITED;
+		if(p->car == &Comma){
+			p = eval(env, p->cdr);
+			p->flag |= VISITED;
+			return p;
+		}
+		p->car = evalcomma(env, p->car);
+		p->cdr = evalcomma(env, p->cdr);
+	}
+	return p;
+}
+
+Object*
+fnbquote(Object *env, Object *list)
+{
+	if(list->cdr != &Nil){
+		printexpr(list);
+		error("fnbquote expected cdr is nil");	
+	}
+	list = evalcomma(env, list->car);
+	return list;
+}
+
 Object*
 fncar(Object *env, Object *list)
 {

main.c

@@ -38,9 +38,6 @@ SExprint(Object *obj)
 	case OMACRO:
 		printf("<macro>");
 		goto func;
-	case OLAMBDA:
-		printf("<lambda>");
-		goto func;
 	case OFUNC:
 		printf("<func>");
 func:

obj.c

@@ -63,6 +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, &Defn, &Macro, &Progn,
+		&Bquote, &Comma,
 	};
 	for(int i = 0; i < sizeof(syms)/sizeof(syms[0]); ++i){
 		Object *c = syms[i];
@@ -84,4 +85,4 @@ newstr(GC *gc, int len)
 	obj->ptr = obj->beg = (char*)&obj[1];
 	obj->end = obj->beg + len;
 	return obj;
-}
+}

parser.c

@@ -7,8 +7,8 @@
 
 const char symbolchars[] = "!*/%-=+<>'";
 
-static Object* lparlist(FILE *);
-static Object* list(FILE *);
+static Object* lparlist(FILE *, int *);
+static Object* list(FILE *, int *);
 
 static char
 get(FILE *f)
@@ -74,10 +74,9 @@ number(FILE *f)
 }
 
 static Object*
-quote(FILE *f)
+quote(FILE *f, Object *car, int *bq)
 {
-	Object *car = &Quote;
-	Object *ccdr = list(f);
+	Object *ccdr = list(f, bq);
 	Object *cdr = newcons(gc, ccdr, &Nil);
 	return newcons(gc, car, cdr);
 }
@@ -116,53 +115,79 @@ atom(FILE *f, char c)
 }
 
 static Object*
-lparlist(FILE *f)
+lparlist(FILE *f, int *bq)
 {
 	Object *car = 0;
 	Object *cdr = 0;
+	Object *res = 0;
 	char c = slookup(f);
 	switch(c){
+	case '`':
+		*bq += 1;
+		get(f);
+		car = quote(f, &Bquote, bq);
+		cdr = lparlist(f, bq);
+		res = newcons(gc, car, cdr);
+		*bq -= 1;
+		return res;
 	case '\'':
 		get(f);
-		car = quote(f);
-		cdr = lparlist(f);
+		car = quote(f, &Quote, bq);
+		cdr = lparlist(f, bq);
+		return newcons(gc, car, cdr);
+	case ',':
+		if(*bq <= 0)
+			error("comma is illegal outside of backquote");
+		get(f);
+		car = newcons(gc, &Comma, list(f, bq));
+		cdr = lparlist(f, bq);
 		return newcons(gc, car, cdr);
 	case '.':
 		get(f);	
-		return list(f);
+		return list(f, bq);
 	case '(':
-		car = list(f);
-		cdr = lparlist(f);
+		car = list(f, bq);
+		cdr = lparlist(f, bq);
 		return newcons(gc, car, cdr);
 	case ')':
 		return &Nil;
+	default:
+		car = atom(f, c);
+		cdr = lparlist(f, bq);
+		return newcons(gc, car ,cdr);
 	}
-	car = atom(f, c);
-	cdr = lparlist(f);
-	return newcons(gc, car ,cdr);
 }
 
 static Object*
-list(FILE *f)
+list(FILE *f, int *bq)
 {
 redo:
+	Object *res = 0;
 	char c = slookup(f);
 	switch(c){
 	case ';':
+		get(f);
 		skipline(f);
 		goto redo;
+	case '`':
+		*bq += 1;
+		get(f);
+		res = quote(f, &Bquote, bq);
+		*bq -= 1;
+		return res;
 	case '\'':
 		get(f);
-		return quote(f);
+		return quote(f, &Quote, bq);
 	case '(':{
 		get(f);
-		Object *obj = lparlist(f);
+		res = lparlist(f, bq);
 		slookup(f);
 		expect(f, ')');
-		return obj;
+		return res;
 		}
+	default:
+		return atom(f, c);
 	}	
-	return atom(f, c);
 }
 
 void
@@ -183,5 +208,10 @@ skipline(FILE *f)
 Object*
 nextexpr(FILE *f)
 {
-	return list(f);
+	int bq = 0;
+	Object *expr = list(f, &bq);
+	if(bq != 0){
+		error("Bad backquote in expr");	
+	}
+	return expr;
 }