Muq MUF provides a simple regular expression syntax roughly comparable to that of Perl 4. (4)

Regular expressions are treated as a sublanguage used to compile
named functions which may then be called just like any other
MUF function. The definition of a regular expression
function begins with the `rex:`

keyword, which is
followed by the function name and then the regular expression
proper, delimited by the printable character of your choice,
typically slashes:

root: rex: re1 /^abc[def]/ root: "abcd" re1 root: t pop "abcg" re1 root: nil pop root: rex: re2 /^abc[d-f]/ root: "abcd" re2 root: t pop "abcg" re2 root: nil pop root: rex: re3 /^abc|def|ghi/ root: "abc" re3 "jkl" re3 root: t nil pop pop root: rex: re4 /^a[bc]*d/ root: "acbd" re4 "acb" re4 root: t nil pop pop root:

The basic Perl4 set of special escape characters are supported:

^ match start of string $ match end of string [a-z] any char from a through z [^a-z] any char BUT a through z \s whitespace \S non-whitespace \d digit: [0-9] \D non-digit \w word character: [0-9a-zA-Z] \W non-word character x* zero or more 'x's. x+ one or more 'x's. x? zero or one 'x'x. x{2,4} two to four 'x's.

Parens in a regular expression serve to group it, and also indicate a part which should be returned as an additional result of the function:

root: rex: re6 /^a(b*)c/ root: "ac" re6 root: t "" pop pop root: "abbbbbbbc" re6 root: t "bbbbbbb" pop pop root: "adc" re6 root: nil ""

As usual, numeric escapes such as `\2`

will match whatever
the corresponding (second, in this case) pair of parens in the
regular expression matched:

root: rex: re5 /^(abc)\1$/ root: "abcabc" re5 root: t "abc" pop pop root: "abcacb" re5 root: nil ""

Regular expressions can be a great aid in digesting formatted text:

root: rex: matchDate /^\s*(\w+)\s*(\d+)(\w*),\s*(\d+)\s*$/ root: " July 4th, 1999 " matchDate root: t "July" "4" "th" "1999" pop pop pop pop pop root: "Aug8,1999" matchDate root: t "Aug" "8" "" "1999"

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