Randomized templating language DSL

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This package is not currently in any snapshots. If you're interested in using it, we recommend adding it to Stackage Nightly. Doing so will make builds more reliable, and allow to host generated Haddocks.

BSD3 licensed by Vanessa McHale

Madlang DSL for generating random text

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This is the Madlang DSL for generating text. You specify a template, and Madlang will create randomized text from the template.

Madlang is an interpreted language, written in Haskell. It runs from the command line, but also provides a Haskell library that can be integrated into other projects, compiled to a web app, or used as an EDSL.

There is also a vim plugin for syntax highlighting, available here.

It can be used for twitter bots (among other things) and provides human-readable syntax for generating text.


An example is worth a thousand words, so suppose you wanted to generate a mediocre fortune telling bot. You could write the following code:

:define person
    0.7 "A close friend will "
    0.3 "You will "
:define goodfortune
    0.2 person "make rain on the planet Mars"
    0.8 "nice things will happen today :)"
:define fortune
    0.5 "drink a boatload of milk"
    0.5 "get angry for no reason"
:define intense
    1.0 person "wrestle in the WWE".to_upper
    1.0 person "bite in a bottle of hot sauce".to_upper
    0.7 person fortune
    0.1 intense
    0.2 goodfortune


There are two keywords in madlang you'll use most: :define and :return. :return is the main string we'll be spitting back; there can be only one per file. :define on the other hand can be used to make functions. These functions are combinations of templates, organizing pairs of weights and strings.

There is a Shakespearean insult generator demo available in demo/shakespeare.mad



If you're on windows or linux, grabbing release binaries simplest. Find them here.


If you're on linux or mac, you can get up-to-date binaries via nix.

Download nix with

curl | sh

From there, nix-env -i madlang will install the proper executables.


Download stack with

curl -sSL | sh

Then run stack install madlang --resolver nightly and you'll get the madlang executable installed on your path. This may take a bit of time, as it will build all dependencies of madlang first.


To use it, try

 $ madlang run demo/shakespeare.mad

You can do madlang --help if you want a couple other options for debugging.

Using the library

One function you might want to use is runFile; it reads a file and generates randomized text:

 λ:> runFile [] "demo/shakespeare.mad"
 "Thou hasty-witted gleeking puttock!"

To use the library as an EDSL, there are two options: splicing in a file or using a quasi-quoter, viz.

demo :: IO T.Text
demo = run
    $(madFile "demo/shakespeare.mad")

demo :: IO T.Text
demo = run [|madlang
:define f
    1.0 "heads"
    1.0 "tails"
    1.0 f|]

Haddock documentation of all library functionality is located here. ## Syntax Highlighting

Syntax highlighting for the DSL is provided in the vim plugin here. It includes integration with syntastic.

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