Morte

Morte is a super-optimizing intermediate language for functional languages.

morte centers around a single idea: a strongly normalizing, typed, and polymorphic lambda calculus is the ideal language for super-optimization of programs. Optimization is just normalization of lambda terms. All abstractions desugar to lambda abstraction.

Quick start

• Install the stack tool
• stack setup
• stack install morte

This creates the morte executable under stack's default bin directory (typically ~/.local/bin/ on Unix-like systems). This executable reads Morte expressions from stdin, type-checks them, outputs their type to stderr and outputs the optimized program to stdout. For example:

$ morte
\(a : *) -> \(x : a) -> x <Enter>
<Ctrl-D>
∀(a : *) → a → a

λ(a : *) → λ(x : a) → x
$ # There was nothing to optimize

To learn more, read the Morte tutorial.

You can also use a front-end. Current front ends are

• Annah

with hopefully more to come.

How to contribute

Morte needs a front-end compiler to translate high-level abstractions to the calculus of constructions and a back-end compiler to translate Morte to an executable. I'm currently working on both of these, but if you would like to contribute then contact me or open an issue on the issue tracker to discuss this.

Development Status

The main volatility in the API is in error reporting, specifically how to preserve better error messages for front-end compilers.

Additionally, morte may eventually switch to using attoparsec instead of alex/happy. When this happens it might affect the grammar in subtle and unanticipated ways.

morte may also eventually expand the grammar and introduce other syntactic niceties, but I'm currently playing it safe and keeping the grammar small for now.

One feature I'd eventually like to implement is the use of free theorems to further simplify Morte code, but this is not urgent and definitely a lower priority than implementing front-end and back-end compilers. If implemented, this would be entirely backwards compatible.

Regenerating .travis.yml

Using https://github.com/hvr/multi-ghc-travis

../multi-ghc-travis/make_travis_yml.hs morte.cabal alex-3.1.4 happy-1.19.5 > .travis.yml

You need to put this in the before_install section so that cabal can find alex and happy:

 - export HAPPYVER=1.19.5
 - export ALEXVER=3.1.4
 - export PATH=/opt/ghc/$GHCVER/bin:/opt/cabal/$CABALVER/bin:/opt/happy/$HAPPYVER/bin:/opt/alex/$ALEXVER/bin:$PATH

License (BSD 3-clause)

Copyright (c) 2014 Gabriella 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 Gabriella 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.