Question

Simple question, simple answer for someone who actually uses scheme. How can I find out if a variable is a letter of the alphabet?

I assumed it was something like this (letter? x) where x is some indefinate type. Can anyone tell me what boolean function could be used?

edit:

How could I make something that looks like this: (somFunction-isALetter? a)
Return: #t

Where a is not a variable.

Answer 1

In Racket, the char-alphabetic? function only takes characters as arguments, but it’s easy to define a function that returns false for all non-characters instead of failing:

(define (letter? x) (and (char? x) (char-alphabetic? x)))