1 files changed, 86 insertions, 0 deletions
diff --git a/stdlib/common.lisp b/stdlib/common.lisp
new file mode 100644
index 0000000..2db5d62
--- /dev/null
+++ b/stdlib/common.lisp
@@ -0,0 +1,86 @@
+(let! compose (\[f g]
+    (\[x] (f (g x)))))
+
+(let! id (\[a] a))
+
+(let! mod (\[n k]
+    (- n (* k (/ n k)))))
+
+(let! not (\[b]
+    (match b
+        true false
+        false true)))
+
+(let! is-even (\[n]
+    (match (mod n 2)
+        0 true
+        1 false)))
+
+(let! is-odd (compose not is-even))
+
+;; map :: (a -> b) -> [a] -> [b]
+(let! map (\[f lst]
+    (match lst
+        []
+            []
+        otherwise
+            (prepend (f (head lst)) (map f (tail lst))))))
+
+(map (+ 1) [1 2 3])
+
+;; foldr :: (a -> b -> b) -> b -> [a] -> b
+(let! foldr (\[f accumulator lst]
+    (match lst
+        []
+            accumulator
+        otherwise
+            (f (head lst) (foldr f accumulator (tail lst))))))
+
+;; filter :: (a -> Bool) -> [a] -> [a]
+(let! filter (\[pred lst]
+    (match lst
+        [] []
+        otherwise (match (pred (head lst))
+            true
+                (prepend (head lst) (filter pred (tail lst)))
+            false
+                (filter pred (tail lst))))))
+
+(let! fibo (\[n]
+    (let! lazy fibo-1 (fibo (- n 1)))
+    (let! lazy fibo-2 (fibo (- n 2)))
+    (match n
+        0  0
+        1  1
+        _  (+ fibo-1 fibo-2))))
+
+(let! reverse_ (\[v a]
+    (let! lazy x (head v))
+    (let! lazy xs (tail v))
+    (let! lazy xa (prepend x a))
+    (match v
+        [] a
+        _  (reverse_ xs xa))))
+
+(let! reverse (\[v]
+    (reverse_ v [])))
+
+(let! flow (\[fs] (foldr compose id (reverse fs))))
+(let! pipe (\[x fs] ((flow fs) x)))
+
+(let! lazy exports [
+    compose
+    id
+    mod
+    not
+    is-even
+    is-odd
+    map
+    foldr
+    filter
+    fibo
+    reverse_
+    reverse
+    flow
+    pipe
+])