Prelude> id . map id $ [1,2]
[1,2]
Prelude> let f q = q . map q $ [1,2] in f id
<interactive>:48:5: error:
• Non type-variable argument in the constraint: Num [b]
(Use FlexibleContexts to permit this) f :: forall b. Num [b] => ([b] -> b) -> b
In the expression: let f q = q . map q $ [...] in f id
In an equation for ‘it’: it = let f q = q . map q $ ... in f id