Implement naive export system

1 files changed, 60 insertions, 0 deletions

diff --git a/stdlib/maybe.lisp b/stdlib/maybe.lisp
new file mode 100644
index 0000000..0bc7ac4
--- /dev/null
+++ b/stdlib/maybe.lisp
@@ -0,0 +1,60 @@
+; LIB
+
+(let! just (\[a]
+    ["maybe" "just" a]))
+(let! nothing (\[]
+    ["maybe" "nothing"]))
+
+(let! unsafe-at (\[n seq]
+    (match seq
+        []
+            (fatal! "unsafe-at out of bounds")
+        otherwise
+            (match n
+                0
+                    (head seq)
+                otherwise
+                    (unsafe-at (- n 1) (tail seq))))))
+
+(let! unpack-just (unsafe-at 2))
+(let! kind (unsafe-at 1))
+
+(let! map (\[f m]
+    (match (kind m)
+        "just" (just (f (unpack-just m)))
+        "nothing" (nothing))))
+
+(let! and-then (\[f m]
+    (match (kind m)
+        "just" (f (unpack-just m))
+        "nothing" (nothing))))
+
+; TESTING
+
+;; (let! print-line! (\[s]
+;;     (print! (concat s "\n"))))
+
+;; (let! a (just 10))
+;; (let! b (nothing))
+
+;; (map (+ 5) a)
+;; (map (+ 5) b)
+
+;; (and-then (\[n] (just (+ n 5))) a)
+;; (and-then (\[n] (just (+ n 5))) b)
+
+;; (let! m (just 10))
+;; (match m
+;;     (just _)
+;;         (print-line! (fmt "found just {0}!" [(unpack-just m)]))
+;;     (nothing)
+;;         (print-line! "found nothing!"))
+
+(let! lazy exports [
+    just
+    nothing
+    unpack-just
+    kind
+    map
+    and-then
+])