(a -> b) -> [a] -> [b] -base -syb +bytestring

(>$<) :: Contravariant f => (b -> a) -> f a -> f b
bytestring Data.ByteString.Builder.Prim
A fmap-like operator for builder primitives, both bounded and fixed size. Builder primitives are contravariant so it's like the normal fmap, but backwards (look at the type). (If it helps to remember, the operator symbol is like ($) but backwards.) We can use it for example to prepend and/or append fixed values to an primitive. > showEncoding ((\x -> ('\'', (x, '\''))) >$< fixed3) 'x' = "'x'" > > fixed3 = char7 >*< char7 >*< char7 Note that the rather verbose syntax for composition stems from the requirement to be able to compute the size / size bound at compile time.