Add record, union concepts

1 files changed, 42 insertions, 0 deletions

diff --git a/stdlib/maybe-with-unions.lisp b/stdlib/maybe-with-unions.lisp
new file mode 100644
index 0000000..53a5024
--- /dev/null
+++ b/stdlib/maybe-with-unions.lisp
@@ -0,0 +1,42 @@
+; LIB
+
+(union! Maybe
+    (just value)
+    (nothing))
+
+(let! Maybe/map (\[f m]
+    (match (kind m)
+        "Maybe/Just" (Maybe/just (f (Maybe/Just/get-value m)))
+        "Maybe/Nothing" (Maybe/nothing))))
+
+(let! Maybe/and-then (\[f m]
+    (match (kind m)
+        "Maybe/Just" (f (Maybe/Just/get-value m))
+        "Maybe/Nothing" (Maybe/nothing))))
+
+; TESTING
+
+;; (let! print-line! (\[s]
+;;     (print! (concat s "\n"))))
+
+;; (let! a (Maybe/just 10))
+;; (let! b (Maybe/nothing))
+
+;; (Maybe/map (+ 5) a)
+;; (Maybe/map (+ 5) b)
+
+;; (Maybe/and-then (\[n] (Maybe/just (+ n 5))) a)
+;; (Maybe/and-then (\[n] (Maybe/just (+ n 5))) b)
+
+;; (let! m (Maybe/just 10))
+;; (match m
+;;     (Maybe/just _)
+;;         (print-line! (fmt "found just {0}!" [(Maybe/Just/get-value m)]))
+;;     (Maybe/nothing)
+;;         (print-line! "found nothing!"))
+
+;; (let! m (Maybe/just 10))
+;; (pipe m [
+;;     (Maybe/map (+ 5))
+;;     (Maybe/and-then (\[val] (Maybe/just (- val 3))))
+;; ])