1 files changed, 73 insertions, 0 deletions
diff --git a/lib/csc/list.scheme b/lib/csc/list.scheme
new file mode 100644
index 0000000..ea25454
--- /dev/null
+++ b/lib/csc/list.scheme
@@ -0,0 +1,73 @@
+(define-library (csc list)
+  (export
+    all
+    any
+    filter
+    foldl
+    foldr
+    intersperse
+    map-maybe)
+  (import (scheme base))
+  (begin
+
+
+    (define (any1 f l)
+      (and (not (null? l))
+           (or (f (car l))
+               (any1 f (cdr l)))))
+
+
+    (define (any f . ls)
+      (and (not (any1 null? ls))
+           (or (apply f (map car ls))
+               (apply any f (map cdr ls)))))
+
+
+    (define (all f . ls)
+      (or (any null? ls)
+          (and (apply f (map car ls))
+               (apply all f (map cdr ls)))))
+
+
+    (define (foldl f acc . ls)
+      (if (any null? ls)
+        acc
+        (apply foldl f (apply f acc (map car ls)) (map cdr ls))))
+
+
+    (define (foldr f acc . ls)
+      (if (any null? ls)
+        acc
+        (apply f (append (map car ls) (list (apply foldr f acc (map cdr ls)))))))
+
+
+    (define (map-maybe f l)
+      (foldr
+        (lambda (x acc)
+          (define fx (f x))
+          (if fx
+            (cons fx acc)
+            acc))
+        '()
+        l))
+
+
+    (define (filter f l)
+      (foldr
+        (lambda (x acc)
+          (if (f x)
+            (cons x acc)
+            acc))
+        '()
+        l))
+
+
+    (define (intersperse sep l)
+      (if (null? l)
+        '()
+        (cons (car l)
+          (foldr
+            (lambda (x acc)
+              (cons sep (cons x acc)))
+            '()
+            (cdr l)))))))