From e50306f64e8c5889df1bdac1a08ea6904cfc7ac1 Mon Sep 17 00:00:00 2001
From: "Yann Esposito (Yogsototh)" <Yann.Esposito@gmail.com>
Date: Thu, 3 Mar 2011 17:04:08 +0100
Subject: [PATCH] Standard library

---
 stdlib.lsp | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)
 create mode 100644 stdlib.lsp

diff --git a/stdlib.lsp b/stdlib.lsp
new file mode 100644
index 0000000..762df9f
--- /dev/null
+++ b/stdlib.lsp
@@ -0,0 +1,51 @@
+(define (not x)         (if x #f #t))
+(define (null? obj)     (if (eqv? obj '()) #t #f))
+(define (list . objs)   objs)
+(define (id obj)        obj)
+(define (flip func)     (lambda (arg1 arg2) (func arg2 arg1)))
+(define (curry func arg1) (lambda (arg) (apply func (cons arg1 (list arg)))))
+(define (compose f g)   (lambda (arg) (f (apply g arg))))
+(define zero?           (curry = 0))
+(define positive?       (curry > 0))
+(define negative?       (curry < 0))
+(define (odd? num)      (= (mod num 2) 1))
+(define (even? num)     (= (mod num 2) 0))
+
+(define (foldr func end lst)
+  (if (null? lst)
+    end
+    (func (car lst) (foldr func end (cdr lst)))))
+
+(define (foldl func accum lst)
+  (if (null? lst)
+    accum
+    (fold1 func (func accum (car lst)) (cdr lst))))
+
+(define fold foldl)
+(define reduce fold)
+
+(define (unfold func init pred)
+  (if (pred init)
+    (cons init '())
+    (cons init (unfold func (func init) pred))))
+
+(define (sum . lst)     (fold + 0 lst))
+(define (product . lst) (fold * 1 lst))
+(define (and . lst)     (fold && #t lst))
+(define (or . lst)      (fold || #f lst))
+
+(define (max first . rest) (fold (lambda (old new) (if (> old new) old new)) first rest))
+(define (min first . rest) (fold (lambda (old new) (if (< old new) old new)) first rest))
+(define (length lst)    (fold (lambda (x y) (+ x 1)) 0 lst))
+(define (reverse lst)   (fold (flip cons) '() lst))
+
+(define (mem-helper pred op) (lambda (acc next) (if (and (not acc) (pred (op next))) next acc)))
+(define (memq obj lst)      (fold (mem-helper (curry eq? obj) id) #f lst))
+(define (memv obj lst)      (fold (mem-helper (curry eqv? obj) id) #f lst))
+(define (member obj lst)    (fold (mem-helper (curry equal? obj) id) #f lst))
+(define (assq obj alist)    (fold (mem-helper (curry eq? obj) car) #f alist))
+(define (assv obj alist)    (fold (mem-helper (curry eqv? obj) car) #f alist))
+(define (assoc obj alist)   (fold (mem-helper (curry equal? obj) car) #f alist))
+
+(define (map func lst)      (foldr (lambda (x y) (cons (func x) y)) '() lst))
+(define (filter pred lst)   (foldr (lambda (x y) (if (pred x) (cons x y) y)) '() lst))