Tony Morris

Or map... Do you know why Set and Map don't have a map function?

map must preserve structure. Consider Set(['a', 'b', 'c']).map(x => x.length) // Set(1)

map only needs to preserve identity and composition. Consider ((->) t) with no length or structure, yet has map.

I can pronounce those characters individually, but I don't understand ((->) t). Can you point me somewhere?

Now substitute (f) with ((->) t) (a -> b) -> ((->) t a) -> ((->) t b) (a -> b) -> (t -> a) -> (t -> b) ∘

I appreciate your effort, but I'm still not getting it. I'm a Fire Keramik. What is ((->) t) in words? Something I can look up?

It is commonly called "reader." Do you know Haskell syntax? map :: (a -> b) -> f a -> f b

I'm haskell-curious. I don't know reader yet though.