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pgrep: grep-like CLI using Parsec parsers instead of regex

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Deprecated in favor of screp

pgrep is a grep-like command-line tool that uses Parsec parser combinators instead of regular expressions for pattern matching. Write patterns using a familiar Haskell-like DSL with combinators like 'some digit', 'string TODO', or 'manyTill anyChar (string END)'.

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Versions [RSS] 0.1.0.0
Dependencies base (>=4.19.0 && <5), containers (>=0.7 && <0.8), directory (>=1.3.8 && <1.4), filepath (>=1.5.4 && <1.6), optparse-applicative (>=0.14 && <0.19), parsec (>=3.1.18 && <3.2), pgrep, process (>=1.6 && <1.7), scrappy-core (>=0.1.0.1 && <0.2) [details]
License BSD-3-Clause
Author Galen Sprout
Maintainer galen.sprout@gmail.com
Uploaded by lazyLambda at 2026-02-24T15:59:48Z
Category Text, Console
Home page https://github.com/Ace-Interview-Prep/pgrep
Bug tracker https://github.com/Ace-Interview-Prep/pgrep/issues
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Executables pgrep
Downloads 3 total (3 in the last 30 days)
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Status Docs available [build log]
Last success reported on 2026-02-24 [all 1 reports]

Readme for pgrep-0.1.0.0

[back to package description]

scrappy-file

File system utilities for the scrappy web scraping library, plus pgrep - a grep-like CLI that uses Parsec parsers instead of regex.

pgrep

Search files using Parsec parser patterns instead of regular expressions.

Installation

cabal build pgrep
cabal install pgrep

Make sure ~/.local/bin is in your PATH:

export PATH="$HOME/.local/bin:$PATH"

Usage

pgrep PATTERN FILE...
pgrep [OPTIONS] PATTERN FILE...

DSL Primitives

Primitive Example Description
char char 'x' Single character
string string "abc" Literal string
anyChar anyChar Any character
digit digit 0-9
letter letter a-z, A-Z
alphaNum alphaNum Letter or digit
space space Single whitespace
spaces spaces Zero or more whitespace
newline newline Newline character
oneOf oneOf "abc" Match one of chars
noneOf noneOf "xyz" Match none of chars

DSL Combinators

Combinator Syntax Description
Sequence p1 >> p2 Run p1 then p2, return p2's result
Concat p1 <+> p2 Run both, concatenate results
Alternative p1 <|> p2 Try p1, else p2
Many many p Zero or more
Some some p One or more
Optional optional p Zero or one
Try try p Backtracking
Between between '(' ')' p Parse between delimiters
Count count 3 p Exactly n repetitions
ManyTill manyTill p end Non-greedy: match p until end

Examples

# Find digits
pgrep 'some digit' file.txt

# Find email patterns
pgrep 'some alphaNum <+> char '\''@'\'' <+> some alphaNum <+> char '\''.'\'' <+> some letter' contacts.txt

# Find TODO comments
pgrep 'string "TODO"' -r ./src/

# Search recursively with extension filter
pgrep -r -e .hs 'string "import"' ./src/

# Count matches
pgrep -c 'digit' data.txt

# JSON output
pgrep --json 'some digit' file.txt

# Non-greedy matching: find everything between X and Y
pgrep 'string "START" <+> manyTill anyChar (string "END")' file.txt

Options

-r, --recursive      Search directories recursively
-e, --extension EXT  Only search files with extension (e.g., .hs, .txt)
-v, --verbose        Verbose output with full match text
-c, --count          Only print count of matches
-q, --quiet          Quiet mode (exit code only)
-m, --max-results N  Maximum number of results to show
--json               Output results as JSON

Output Format

Default output is grep-like:

file.txt:1:28:123
file.txt:2:5:test@example.com

Format: filepath:line:column:matched_text

Library API

The Scrappy.Grep.* modules expose:

  • Scrappy.Grep.DSL - AST types (ParserExpr, MatchResult)
  • Scrappy.Grep.DSL.Parser - Parse DSL strings to AST
  • Scrappy.Grep.DSL.Interpreter - Convert AST to Parsec parsers
  • Scrappy.Grep.Search - File/directory search functions
  • Scrappy.Grep.Output - Result formatting