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-rw-r--r--examples/maybe.lisp28
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diff --git a/examples/maybe.lisp b/examples/maybe.lisp
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+++ b/examples/maybe.lisp
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+; LIB
+
+(let just (\[a]
+ ["maybe" "just" a]))
+(let nothing (\[]
+ ["maybe" "nothing"]))
+
+(let at (\[n seq]
+ (match seq
+ [] (nothing)
+ (match n
+ 0 (head seq)
+ (at (- n 1) (tail seq))))))
+
+(let from-just (at 2))
+(let kind (at 1))
+
+(let map (\[f m]
+ (match (kind m)
+ "just" (just (f (from-just m)))
+ "nothing")))
+
+; TESTING
+
+(let m (just 10))
+(match (kind m)
+ "just" (from-just m)
+ "nothing" "nothing")