haskell

wildling

Haskell library and CLI for pattern-based string generation. Zero third-party packages (GHC boot libraries only; hand-rolled JSON for templates). Targets GHC 9.0+.

Docs: Website · Sandbox · Syntax · Source

Example

http://${'dev,stage,prod'}\-${'api,web'}#{0-2}.example.${'com,net,org'}/@.html

(The \- is a literal hyphen; bare - would mean “one letter or digit”. @ is one lowercase letter.)

That builds URL-shaped candidates: scheme http://, then environment × service × optional digits × TLD, then a one-letter path page. Three environments, two services, zero–two digits ('', 0–9, 00–99), three TLDs, and a–z → 51948 strings — the kind of list you generate for fuzzing links or probing staging hosts, not type out.

A few of them:

• http://dev-api.example.com/a.html / http://stage-web.example.com/z.html
• http://dev-api0.example.net/a.html / http://prod-web9.example.org/m.html
• http://dev-api00.example.com/a.html / http://prod-web99.example.org/z.html

Named dictionaries (%{'hosts'}) work the same way when the word lists live in files.

Try it in the sandbox, or see pattern syntax for length ranges, dictionaries, and escapes.

Install

From this repository:

cd haskell
./build.sh
./bin/wildling "Year 19##"

From a release tag:

git clone --branch v2.0.7 --depth 1 https://github.com/dotmonk/wildling.git
cd wildling
./build.sh haskell

Produces dist/wildling plus dist/help.txt.

import qualified Data.Map.Strict as Map
import Wildling (createWildling, wildlingNext, WildlingResult(..))

main :: IO ()
main = do
  w <- createWildling ["Year 19##"] Map.empty
  let loop = do
        value <- wildlingNext w
        case value of
          WildlingFalse -> pure ()
          WildlingString s -> putStrLn s >> loop
  loop

CLI

./bin/wildling "Year 19##"
./bin/wildling --dictionary planets:../dictionaries/planets.txt "%{'planets'}"
./bin/wildling --template ./config.json

Help text and --check output follow docs/cli.md / docs/help.txt. Out-of-range --select / --range write out of range: <index> on stderr and exit 1.

Build

./build.sh   # Docker (gcc:14-bookworm): fetch GHC into .ghc (or apt fallback), ghc → dist/wildling

Project tests live in ../tests/ and are run with ../test.sh.