Not finding instances for `(->)`

[Synthetica9]

Examples:

• liftA2 :: (b -> c -> d) -> (a -> b) -> (a -> c) -> (a -> d), No results found
  • liftA3 :: (b -> c -> d -> e) -> (a -> b) -> (a -> c) -> (a -> d) -> (a -> e), No results found
• (<*>) :: (a -> b -> c) -> (a -> b) -> (a -> c), Wrong results found
• join :: (a -> a -> b) -> (a -> b), wrong results found

Same for Arrow instances.

[ndmitchell]

Instances for -> are pretty tricky - I'm not sure they will ever work, but good to record it.

[treeowl]

Relatedly(?), I tried searching for

(a -> b) -> (b -> c) -> a -> c

and

cat a b -> cat b c -> cat a c

but neither turned up Control.Category.>>>. To get it, I had to go all the way to

Category cat => cat a b -> cat b c -> cat a c

which doesn't seem very helpful for discovering the function.

Similarly, I tried

[a] -> [a]

and

[String] -> [String]

and neither turned up Data.List.sort. Hmm.....