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Snap project starter executable plus some libraries for building web apps
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NOTE: 0.6 requires Chris Smith's fork of the configurator package. It is available here:

Snap Framework

This is the first developer prerelease of the Snap Framework snap tool. For more information about Snap, read the or visit the Snap project website at

Snap is a nascent web framework for Haskell, based on iteratee I/O (as popularized by Oleg Kiselyov).

Library contents

This is the snap executable and supporting library, which contains:

  • a command-line utility for creating initial Snap applications

  • a library allowing Snap applications to recompile actions on the fly in development mode, with no performance loss in production mode.

Building snap

The snap tool and library are built using Cabal and Hackage. Just run

cabal install

from the snap toplevel directory.

Building the Haddock Documentation

The haddock documentation can be built using the supplied shell script:


The docs get put in dist/doc/html/.

Building the testsuite

Snap is still in its very early stages, so most of the "action" (and a big chunk of the code) right now is centred on the test suite. Snap aims for 100% test coverage, and we're trying hard to stick to that.

To build the test suite, cd into the test/ directory and run

$ cabal configure
$ cabal build

From here you can invoke the testsuite by running:

$ ./

The testsuite generates an hpc test coverage report in test/dist/hpc.

Roadmap to Understanding Snaplets

  1. Read
  2. Generate and read the haddock docs.
  3. Look at the code in the example directory, and the example applications in the test directory. The test code has the nice property that it actually functions as a pretty good example app and covers a lot of the use cases.
  4. If you're interested in the implementation, read
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