Adds apply and lt (<) to sl3.c

sl3-apply.patch

--- sl3.c	2008-02-07 02:29:40.000000000 +0000
+++ sl3-apply.c	2013-10-18 21:01:20.000000000 +0100
@@ -33,7 +33,7 @@
 } obj;
 typedef obj * (*primop)(obj *);
 obj *all_symbols, *top_env, *nil, *tee, *quote, 
-    *s_if, *s_lambda, *s_define, *s_setb;
+    *s_if, *s_lambda, *s_define, *s_apply, *s_setb;
 
 #define cons(X, Y)            omake(CONS, 2, (X), (Y))
 #define car(X)                ((X)->p[0])
@@ -224,6 +224,11 @@
 		  setcdr(pair, newval);
 		  return newval;
 		}
+                if(car(exp) == s_apply) {
+                  obj *proc = eval(car(cdr(exp)), env);
+                  obj *args = eval(car(cdr(cdr(exp))), env);
+                  return apply(proc, args, env);
+                }
 		return apply(eval(car(exp), env), evlis(cdr(exp), env), env);
     case PRIMOP: return exp;
     case PROC:   return exp;
@@ -286,6 +291,10 @@
   return intval(car(args)) == intval(car(cdr(args))) ? tee : nil;
 }
 
+obj *prim_lt(obj *args) {
+  return intval(car(args)) < intval(car(cdr(args))) ? tee : nil;
+}
+
 obj *prim_cons(obj *args) { return cons(car(args), car(cdr(args))); }
 obj *prim_car(obj *args)  { return car(car(args)); }
 obj *prim_cdr(obj *args)  { return cdr(car(args)); }
@@ -301,11 +310,13 @@
   s_if     = intern("if");
   s_lambda = intern("lambda");
   s_define = intern("define");
+  s_apply  = intern("apply");
   s_setb   = intern("set!");
   extend_top(intern("+"), mkprimop(prim_sum));
   extend_top(intern("-"), mkprimop(prim_sub));
   extend_top(intern("*"), mkprimop(prim_prod));
   extend_top(intern("="), mkprimop(prim_numeq));
+  extend_top(intern("<"), mkprimop(prim_lt));
   extend_top(intern("cons"), mkprimop(prim_cons));
   extend_top(intern("car"),  mkprimop(prim_car));
   extend_top(intern("cdr"),  mkprimop(prim_cdr));

http://www.sonoma.edu/users/l/luvisi/sl3.c