394 B
394 B
Composition problem
The Problem; example with lists:
f x = [x] ⇒ f 1 = [1] ⇒ (f.f) 1 = [[1]] ✗
g x = [x+1] ⇒ g 1 = [2] ⇒ (g.g) 1 = ERROR [2]+1 ✗
h x = [x+1,x*3] ⇒ h 1 = [2,3] ⇒ (h.h) 1 = ERROR [2,3]+1 ✗
The same problem with most f :: a -> F a
functions and functor F
.