How to return the next letter in the alphabet of given letter wrapped around in Haskell
char, haskell, modulo
Solution
Two ways come to mind
import Data.Char
returnNext c = chr (((1 + ord c - ord 'A') `mod` 26) + ord 'A')
Which is kind of ugly to say the least.
And:
returnNext 'Z' = 'A'
returnNext c = chr (ord c + 1)
Both behave differently when not given a letter of the alphabet, but since you didn't specify what should happen in this case I'll assume it's OK.
Problem
I'm trying to implement a function that returns the next letter in alphabetical order. For example: ``` > returnNext 'A' 'B' ``` But also: ``` > returnNext 'Z' 'A' ``` The function should thus cycle between char codes in alphabetical order (mod 26).