No instance for (Show ([(Char, Char)] -> Char))

Question

So I have to make a function that finds a pair with its 1st letter and returning the 2nd letter.

I actually found one answer but with the map function and I couldn\'

Answer 1

It seems that you typed something like this in ghci:

*Main> lookUp 'c'

An expression like lookUp 'c' is a partial evaluation / curried form of the lookUp function. It's type is:

*Main> :t lookUp 'c'
lookUp 'c' :: [(Char, Char)] -> Char

which is the exact type that ghci says there is no Show instance for.

To test your function, be sure to supply both x and the the list of Char pairs:

*Main> lookUp 'c' [ ('a','A'), ('b','B'), ('c','C') ]
'C'