screp
A grep-like CLI that uses Parsec parser combinators instead of regex.
Installation
cabal build screp
cabal install screp
Make sure ~/.local/bin is in your PATH:
export PATH="$HOME/.local/bin:$PATH"
Or install from Hackage:
cabal install screp
Usage
screp PATTERN FILE...
screp [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 |
| Ref |
ref "name" |
Named parser from import file |
Examples
# Find digits
screp 'some digit' file.txt
# Find email patterns (inline)
screp 'some alphaNum <+> char '\''@'\'' <+> some alphaNum <+> char '\''.'\'' <+> some letter' contacts.txt
# Find TODO comments
screp 'string "TODO"' -r ./src/
# Search recursively with extension filter
screp -r -e .hs 'string "import"' ./src/
# Count matches
screp -c 'digit' data.txt
# JSON output
screp --json 'some digit' file.txt
# Non-greedy matching: find everything between X and Y
screp 'string "START" <+> manyTill anyChar (string "END")' file.txt
Using Custom Parsers (--import)
For complex patterns, define parsers in a Haskell file and reference them with ref:
Parsers.hs:
module Parsers (parsers) where
import Text.Parsec
import Text.Parsec.String
import Data.Map (Map)
import qualified Data.Map as Map
parsers :: Map String (Parser String)
parsers = Map.fromList
[ ("email", email)
, ("phone", phone)
]
email :: Parser String
email = do
user <- many1 alphaNum
char '@'
domain <- many1 alphaNum
char '.'
tld <- many1 letter
pure $ user ++ "@" ++ domain ++ "." ++ tld
phone :: Parser String
phone = do
a <- count 3 digit
char '-'
b <- count 3 digit
char '-'
c <- count 4 digit
pure $ a ++ "-" ++ b ++ "-" ++ c
Usage:
# Find emails using custom parser
screp --import Parsers.hs 'ref "email"' contacts.txt
# Find phone numbers
screp --import Parsers.hs 'ref "phone"' contacts.txt
Requirements for custom parsers:
- Module must export
parsers :: Map String (Parser String)
- Requires
parsec and containers packages installed
Options
-r, --recursive Search directories recursively
-e, --extension EXT Only search files with extension (e.g., .hs, .txt)
-i, --import FILE Haskell file with named parsers (for 'ref "name"')
-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
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.Config - External parser execution via runghc
Scrappy.Grep.Output - Result formatting
