cooler macro example

1 files changed, 22 insertions, 4 deletions

diff --git a/files/test-lambda.l b/files/test-lambda.l
index b29ed7b..29e1f52 100644
--- a/files/test-lambda.l
+++ b/files/test-lambda.l
@@ -54,8 +54,6 @@
 (defmacro m (a) `(+ ,a 57))
 (m (+ 1 2))
 
-(define cadr (lambda (l) (car (cdr l))))
-
 (define map (lambda (fn list)
               (if (nil? list)
                   list
@@ -63,7 +61,27 @@
 
 (map (lambda (n) (+ n 1)) '(1 2 3))
 
+(define foldl (lambda (fn acc l)
+                (if (nil? l) acc
+                    (foldl fn (fn (car l) acc) (cdr l)))))
+(define foldr (lambda (fn acc l)
+                (if (nil? l) acc
+                    (fn (car l) (foldr fn acc (cdr l))))))
+
+
+(define cdar (lambda (l) (car (cdr l))))
+
 (defmacro let (vars body)
-  `((lambda ,(map car vars) ,body) . ,(map cadr vars)))
+  `((lambda ,(map car vars) ,body) . ,(map cdar vars)))
+
+(defmacro let* (vars body)
+  (foldr (lambda (var rest) `(let (,var) ,rest)) body vars))
+
+(let ((a 9)
+      (b 13))
+  (+ a b))
 
-(let ((a 8) (b 9)) (+ a b))
+(let* ((a 8)
+       (b (- a 3))
+       (c (+ a b)))
+  (- c 3))