markwright / haskell-mvc-library

Model-view-controller

MVC v1.1.6

Use the mvc library to distill concurrent programs into pure and single-threaded programs using the Model-View-Controller pattern. The mvc library makes pervasive purity practical.

mvc is guided by a single overarching design principle: application architectures inspired by category theory scale in the large because they reduce complexity and prevent proliferation of concepts. Use mvc if you wish to learn how to practically apply theory to tame large applications.

Quick start

• Install the Haskell Platform
• cabal install mvc
• Read the documentation in the MVC module and the MVC.Prelude module

Optionally begin from this program skeleton:

import MVC
import qualified MVC.Prelude as MVC
import qualified Pipes.Prelude as Pipes

external :: Managed (View String, Controller String)
external = do
    c1 <- MVC.stdinLines
    c2 <- MVC.tick 1
    return (MVC.stdoutLines, c1 <> fmap show c2)

model :: Model () String String
model = asPipe (Pipes.takeWhile (/= "quit"))
    
main :: IO ()
main = runMVC () model external

Features

• Determinism: Perform property-based testing on your model (like QuickCheck)

• Purity: Move a substantial amount of your application logic into pure code

• Semantics: Equationally reason about your concurrency-free and pure core

• Best practices: Statically enforce decoupling

• Concise API: Only four types, and 8 primitive functions

• Elegant semantics: Use practical category theory

• Extensive Documentation: The haddocks contain extensive tips and idioms

Development Status

The API is stable because I do not plan to generalize the API further. Any future generalizations will be released as separate libraries. The goal of this library is to serve as a stepping stone towards understanding more sophisticated and general application architectures, so I wish to preserve its simplicity for pedagogical reasons.

Future development will focus on building an ecosystem of pre-built Views and Controllers that applications can use, with a focus on tools useful for user interfaces and games.

How to contribute

• Build derived libraries

• Write mvc tutorials

License (BSD 3-clause)

Copyright (c) 2014 Gabriel Gonzalez All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

• Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

• Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

• Neither the name of Gabriel Gonzalez nor the names of other contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.