Community

• Brew (macOS and Linux)

brew install melody

• Arch Linux (maintained by @ilai-deutel)

paru -Syu melody

git clone https://aur.archlinux.org/melody.git
     cd melody
     makepkg -si

• NixOS (maintained by @jyooru)

{ pkgs, ... }:
     {
       environment.systemPackages = with pkgs; [
         melody
       ];
     }

nix-env -iA nixos.melody

CLI Usage

USAGE:
    melody [OPTIONS] [INPUTFILEPATH]
ARGS:     <INPUTFILEPATH>    Read from a file                          Use '-' and or pipe input to read from stdin
OPTIONS:     -f, --test-file <TEST_FILE>             Test the compiled regex against the contents of a file
--generate-completions <COMPLETIONS>             Outputs completions for the selected shell             To use, write the output to the appropriate location for your shell
-h, --help             Print help information
-n, --no-color             Print output with no color
-o, --output <OUTPUTFILEPATH>             Write to a file
-r, --repl             Start the Melody REPL
-t, --test <TEST>             Test the compiled regex against a string
-V, --version             Print version information

Changelog

See the changelog here or in the release page

Syntax

Quantifiers

• ... of - used to express a specific amount of a pattern. equivalent to regex {5} (assuming 5 of ...)
• ... to ... of - used to express an amount within a range of a pattern. equivalent to regex {5,9} (assuming 5 to 9 of ...)
• over ... of - used to express more than an amount of a pattern. equivalent to regex {6,} (assuming over 5 of ...)
• some of - used to express 1 or more of a pattern. equivalent to regex +
• any of - used to express 0 or more of a pattern. equivalent to regex *
• option of - used to express 0 or 1 of a pattern. equivalent to regex ?

Symbols

• <char> - matches any single character. equivalent to regex .
• <space> - matches a space character. equivalent to regex
• <whitespace> - matches any kind of whitespace character. equivalent to regex \s or [ \t\n\v\f\r]
• <newline> - matches a newline character. equivalent to regex \n
• <tab> - matches a tab character. equivalent to regex \t
• <return> - matches a carriage return character. equivalent to regex \r
• <feed> - matches a form feed character. equivalent to regex \f
• <null> - matches a null characther. equivalent to regex \0
• <digit> - matches any single digit. equivalent to regex \d or [0-9]
• <vertical> - matches a vertical tab character. equivalent to regex \v
• <word> - matches a word character (any latin letter, any digit or an underscore). equivalent to regex \w or [a-zA-Z0-9_]
• <alphabetic> - matches any single latin letter. equivalent to regex [a-zA-Z]
• <alphanumeric> - matches any single latin letter or any single digit. equivalent to regex [a-zA-Z0-9]
• <boundary> - Matches a character between a character matched by <word> and a character not matched by <word> without consuming the character. equivalent to regex \b
• <backspace> - matches a backspace control character. equivalent to regex [\b]

Special Symbols

• <start> - matches the start of the string. equivalent to regex ^
• <end> - matches the end of the string. equivalent to regex $

Unicode Categories

Note: these are not supported when testing in the CLI (-t or -f) as the regex engine used does not support unicode categories. These require using the u flag.

• <category::letter> - any kind of letter from any language

• <category::mark> - a character intended to be combined with another character (e.g. accents, umlauts, enclosing boxes, etc.)

• <category::separator> - any kind of whitespace or invisible separator

• <category::symbol> - math symbols, currency signs, dingbats, box-drawing characters, etc

• <category::number> - any kind of numeric character in any script

• <category::punctuation> - any kind of punctuation character

• <category::other> - invisible control characters and unused code points

These descriptions are from regular-expressions.info

Character Ranges

• ... to ... - used with digits or alphabetic characters to express a character range. equivalent to regex [5-9] (assuming 5 to 9) or [a-z] (assuming a to z)

Literals

• "..." or '...' - used to mark a literal part of the match. Melody will automatically escape characters as needed. Quotes (of the same kind surrounding the literal) should be escaped

Raw

• \...\ - added directly to the output without any escaping

Groups

• capture - used to open a capture or named capture block. capture patterns are later available in the list of matches (either positional or named). equivalent to regex (...)
• match - used to open a match block, matches the contents without capturing. equivalent to regex (?:...)
• either - used to open an either block, matches one of the statements within the block. equivalent to regex (?:...|...)

Assertions

• ahead - used to open an ahead block. equivalent to regex (?=...). use after an expression
• behind - used to open an behind block. equivalent to regex (?<=...). use before an expression

Variables

• let .variablename = { ... } - defines a variable from a block of statements. can later be used with .variablename. Variables must be declared before being used. Variable invocations cannot be quantified directly, use a group if you want to quantify a variable invocation

let .aandb = {
    "a";
    "b";
  }
.aandb;   "c";
// abc

Extras

• / ... /, // ... - used to mark comments (note: // ... comments must be on separate line)

File Extension

The Melody file extensions are .mdy and .melody

Crates

• melodycompiler - The Melody compiler 📦 📖
• melodycli - A CLI wrapping the Melody compiler 📦 📖
• melody_wasm - WASM bindings for the Melody compiler

compiler/normal (8 lines)
                            time:   [4.3556 µs 4.3674 µs 4.3751 µs]
  slope  [4.3556 µs 4.3751 µs] R^2            [0.9996144 0.9996931]
  mean   [4.3377 µs 4.3678 µs] std. dev.      [16.019 ns 30.154 ns]
  median [4.3270 µs 4.3777 µs] med. abs. dev. [3.1402 ns 41.334 ns]

compiler/long input (1M lines)
                            time:   [470.04 ms 472.35 ms 474.78 ms]
  mean   [470.04 ms 474.78 ms] std. dev.      [2.0458 ms 5.3453 ms]
  median [469.54 ms 475.24 ms] med. abs. dev. [734.10 µs 6.8144 ms]

compiler/deeply nested
                            time:   [4.2357 µs 4.2561 µs 4.2782 µs]
  slope  [4.2357 µs 4.2782 µs] R^2            [0.9988854 0.9988087]
  mean   [4.2474 µs 4.2752 µs] std. dev.      [13.698 ns 29.574 ns]
  median [4.2426 µs 4.2819 µs] med. abs. dev. [2.7127 ns 43.193 ns]