Matches an integer.

parse "42" int -- Ok 42

Matches a "word", comprised of alphanumeric characters and _.

parse "hello world" word -- Ok "hello"

Matches an alphabetic character.

Matches an alphanumeric character.

Matches a digit, e.g. 8.

Matches an uppercase alphabetic characters, e.g. A.

Matches a lowercase alphabetic characters, e.g. z.

Matches the space character, ``.

Matches the tab character, \t.

Matches either a space or a tab.

Matches zero or more blank characters.

Matches a newline character.