From e6aeef5e54759c26912c4987cb86b3add2d77349 Mon Sep 17 00:00:00 2001
From: Felix Perktold <Felix.Perktold@student.uibk.ac.at>
Date: Tue, 13 Jan 2026 14:16:10 +0100
Subject: added some lisp functions

---
 Makefile                     |  3 +++
 lisp.c                       |  8 ++++++--
 lisp/standard_functions.lisp | 40 +++++++++++++++++++++++++++++++++++++---
 3 files changed, 46 insertions(+), 5 deletions(-)

diff --git a/Makefile b/Makefile
index 095a7ae..a04723e 100644
--- a/Makefile
+++ b/Makefile
@@ -37,4 +37,7 @@ test.o: test.c lisp.h lex.yy.o
 run: main
 	./main
 
+run_std: main
+	./main lisp/standard_functions.lisp
+
 .PHONY: clean test run
diff --git a/lisp.c b/lisp.c
index a559330..4e143f1 100644
--- a/lisp.c
+++ b/lisp.c
@@ -222,7 +222,7 @@ value *eval(env *e, value *v) {
 		if (!found) {
 			printf("symbol %s not found\n", v->as.sym);
 			return cons(make_symbol("quote"),
-				cons(v, make_nil()));
+				cons(v, make_nil())); //TODO: return error
 		}
 		return found;
 	}
@@ -318,9 +318,13 @@ value *apply(value *lval, value *args) {
 		value *result = eval(sub_env, lval->as.lambda.body);
 
 		// if arguments left, try applying them to evaluated lambda
-		if (arg->type == VT_PAIR) {
+		if (arg->type == VT_PAIR && result->type == VT_LAMBDA) {
 			return apply(result, arg);
 		}
+		// if arguments left but result is not a lambda, explicitely return false TODO: return an error
+		if (arg->type == VT_PAIR) {
+			return make_nil();
+		}
 		return result;
 	}
 
diff --git a/lisp/standard_functions.lisp b/lisp/standard_functions.lisp
index 9658ef9..5ad4298 100644
--- a/lisp/standard_functions.lisp
+++ b/lisp/standard_functions.lisp
@@ -1,15 +1,49 @@
-; comparisons
+;; comparisons
 (define <= (lambda (x y)
     (if (< x y)
       1
-      (if (eq? x y) 1 ()))))
+      (if (equal? x y) 1 ()))))
 (define > (lambda (x y) (< y x)))
 (define >= (lambda (x y) (<= y x)))
 
-; boolean funs
+(define even? (lambda (n)
+               (if (equal? n 0)
+                 1
+                 (odd? (- n 1)))))
+
+(define odd? (lambda (n)
+               (if (equal? n 0)
+                 ()
+                 (even? (- n 1)))))
+;; boolean funs
 (define and (lambda (x y)
               (if x 
                 (if y 1 ())
                 ())))
 (define or (lambda (x y) (if x 1 y)))
+(define xor (lambda (x y) (if x (null? y) y)))
 (define nand (lambda (x y) (null? (and x y))))
+
+;; common recursive functions
+(define ! (lambda (n)
+            (if (equal? n 0)
+              1
+              (* n
+                 (! (- n 1))))))
+
+(define fib (lambda (n)
+              (if (<= n 2)
+                1
+                (+ (fib (- n 1))
+                   (fib (- n 2))))))
+
+(define ack (lambda (n m)
+              (if (equal? n 0)
+                (+ m 1)
+                (if (equal? m 0)
+                  (print (ack (print (- n 1)) (print 1)))
+                  (ack (- n 1) (ack n (- m 1)))))))
+
+(define seq (lambda (n)
+              (seq (print (+ n 1)))))
+
-- 
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