{-| Match a letter or digit

>>> match alphaNum "1"
"1"
>>> match alphaNum "a"
"a"
>>> match alphaNum "A"
"A"
>>> match alphaNum "."
""
-}
alphaNum :: Pattern Char
alphaNum = satisfy isAlphaNum
alphaNum :: Pattern Char
alphaNum = satisfy isAlphaNum
alphaNum = satisfy isAlphaNum