Category "type-deduction"

How template deduce const pointer type?

I've tried following codes in cppinsights: #include <iostream> #include <string> #include <type_traits> #include <vector> template<t

What does " Non type-variable argument in the constraint" really mean?

For example: map (+1) 2 in ghci yields <interactive>:23:1: error: * Non type-variable argument in the constraint: Num [b] (Use FlexibleContexts to