Regex Module

Compiled regular expression patterns for matching, searching, replacing, and splitting strings.

Functions

`Regex.captures`

Regex -> String -> Maybe [Maybe String]

Return the capture groups from the first match of a regex.

Example:

import Regex
import Result

case Regex.compile "([0-9]{4})-([0-9]{2})-([0-9]{2})" of
    Ok r  -> Regex.captures r "2024-01-15"
    Err _ -> Nothing

-- Just [Just "2024", Just "01", Just "15"]

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Notes: Returns Nothing if the pattern does not match. The whole match (group 0) is excluded; only numbered capture groups are returned. Optional groups that did not participate in the match appear as Nothing.

See also: Regex.find, Regex.findAll

`Regex.compile`

String -> Result Regex String

Compile a regular expression pattern string into a Regex value.

Example:

import Regex
import Result

case Regex.compile "[0-9]+" of
    Ok r  -> Regex.test r "abc123"
    Err e -> False

-- True

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Notes: Uses the regex crate syntax. Returns Err with a descriptive message if the pattern is invalid.

See also: Regex.test, Regex.find

`Regex.find`

Regex -> String -> Maybe String

Find the first match of a regex in the input string.

Example:

import Regex
import Result

case Regex.compile "[0-9]+" of
    Ok r  -> Regex.find r "abc123def456"
    Err _ -> Nothing

-- Just "123"

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See also: Regex.findAll, Regex.captures

`Regex.findAll`

Regex -> String -> [String]

Find all non-overlapping matches of a regex in the input string.

Example:

import Regex
import Result

case Regex.compile "[0-9]+" of
    Ok r  -> Regex.findAll r "a1b22c333"
    Err _ -> []

-- ["1", "22", "333"]

Try it

See also: Regex.find, Regex.captures

`Regex.replace`

Regex -> String -> String -> String

Replace the first match of a regex in the input string.

Example:

import Regex
import Result

case Regex.compile "[0-9]+" of
    Ok r  -> Regex.replace r "X" "a1b22c333"
    Err _ -> "a1b22c333"

-- "aXb22c333"

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Notes: Only the first match is replaced. Use replaceAll to replace every match.

See also: Regex.replaceAll

`Regex.replaceAll`

Regex -> String -> String -> String

Replace all non-overlapping matches of a regex in the input string.

Example:

import Regex
import Result

case Regex.compile "[0-9]+" of
    Ok r  -> Regex.replaceAll r "X" "a1b22c333"
    Err _ -> "a1b22c333"

-- "aXbXcX"

Try it

See also: Regex.replace

`Regex.split`

Regex -> String -> [String]

Split the input string on all matches of a regex.

Example:

import Regex
import Result

case Regex.compile "\\s+" of
    Ok r  -> Regex.split r "hello world  foo"
    Err _ -> []

-- ["hello", "world", "foo"]

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Notes: If the pattern does not match, returns a single-element list containing the whole input.

See also: Regex.findAll

`Regex.test`

Regex -> String -> Bool

Test whether a compiled regex matches anywhere in the input string.

Example:

import Regex
import Result

case Regex.compile "^[0-9]+$" of
    Ok r  -> Regex.test r "12345"
    Err _ -> False

-- True

Try it

See also: Regex.compile, Regex.find