Make prev and next faster (#74)

elm-community · Dec 17, 2021 · a4562d6 · a4562d6
1 parent 9c1276b
commit a4562d6
Showing 1 changed file with 14 additions and 4 deletions.
diff --git a/src/Maybe/Extra.elm b/src/Maybe/Extra.elm
@@ -698,8 +698,13 @@ Advanced functional programmers will recognize this as the implementation of `*>
 
 -}
 next : Maybe a -> Maybe b -> Maybe b
-next =
- map2 (\b a -> always a b)
+next a b =
+ case a of
+ Nothing ->
+ Nothing
+
+ Just _ ->
+ b
 
 
 {-| Take two `Maybe` values. If the second one equals `Nothing`, return `Nothing`. Otherwise return the first value.
@@ -717,5 +722,10 @@ Advanced functional programmers will recognize this as the implementation of `<*
 
 -}
 prev : Maybe a -> Maybe b -> Maybe a
-prev =
- map2 always
+prev a b =
+ case b of
+ Nothing ->
+ Nothing
+
+ Just _ ->
+ a