3 Couldn't match type `a' with `t a'
4 `a' is a rigid type variable bound by
5 a type expected by the context: [a] -> [t a] at mc22.hs:10:9
6 Expected type: [a] -> [t a]
7 Actual type: [a] -> [a]
8 Relevant bindings include foo :: [t [Char]] (bound at mc22.hs:8:1)
9 In the return type of a call of `take'
10 In the expression: take 5
11 In a stmt of a monad comprehension: then group using take 5