chickadee » srfi-14 » char-set:letter

In Unicode, a letter is any character with one of the letter categories (Lu, Ll, Lt, Lm, Lo) in the Unicode character database.

There are 52 ASCII letters

abcdefghijklmnopqrstuvwxyz ABCDEFGHIJKLMNOPQRSTUVWXYZ

There are 117 Latin-1 letters. These are the 115 characters that are members of the Latin-1 char-set:lower-case and char-set:upper-case sets, plus

(These two letters are considered lower-case by Unicode, but not by SRFI 14.)