haskell - Removing duplication (with Applicative ((->) t), perhaps?) -


i playing around simple function else's stack overflow question, , wrote expression:

f x ++ f y

obviously best way write expression in real life, given have variables in scope anyway, saw duplication of f a, , thought "hey, maybe can remove applicative instance functions". wound with: 

lifta2 (++) (flip f x) (flip f y)

which awful. there nicer way remove duplication?obviously remove duplication binding f a in where clause, intended exercise in using built-in functions.

you do

((++) `on` f a) x y

that doesn't use applicative, though (sorry).


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