Math.Checksum.ISBN

International Standard Book Number

https://en.wikipedia.org/wiki/International_Standard_Book_Number

Covers only ISBN-10. For ISBN-13 simply use Math.Checksum.EAN.

Documentation

checksum :: String -> Exceptional String Int

checksum "346811124" == Success 10

valid :: String -> Maybe String

valid "346811124X" == Nothing
valid "3468111240" == Just "check sum does not match"