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UnnaturalCode is a system with the purpose of augmenting the compiler's own syntax error location strategies. It is designed to assist the developer in locating syntax errors in their software. For more information, please consult the UnnaturalCode paper (preprint).

UnnaturalCode should be considered proof-of-concept quality software. The primary author of UnnaturalCode, Hazel Victoria Campbell can be reached at


Clone this repository with the recursive option:

git clone --recursive

Alternatively, clone this repository, then initialize git-submodules.

git submodule update --init

This will also clone MITLM.

macOS: MITLM requires gfortran, which must be installed before running pip install.

brew install gcc

Then, prior to the pip install, set the LIBRARY_PATH as appropriate:

export LIBRARY_PATH="$(dirname $(brew list gcc | grep libgfortran.a | tail -1)):$LIBRARY_PATH"

Create a virtualenv (optional), then:

pip install -e .

Must set the PATH for the following compilers:


  • Babel
  • V8
  • EsLint
  • JavaScriptCore

Execute the following for each compiler:


An example for Babel:

export PATH=/home/dhvani/node_modules/.bin:$PATH

Requirement for Java:

Path to ecj-4.7.jar (Eclipse compiler standalone jar) must be set in


To start the HTTP server:

python -m unnaturalcode.http


Assume that UnnaturalCode is licensed under the AGPL3+ unless otherwise specified.

© 2010-2012 Abram Hindle, Prem Devanbu, Earl T. Barr, Daryl Posnett

© 2012-2014 Hazel Victoria Campbell, Abram Hindle, Alex Wilson

UnnaturalCode is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

UnnaturalCode is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more details.

You should have received a copy of the GNU Affero General Public License along with UnnaturalCode. If not, see

Academic Use

Now we aren't going to impose any extra requirements, but we ask kindly if you are using this academically that you should consider citing our relevant work:

  author =       {Joshua Charles Campbell and Abram Hindle and José Nelson Amaral},
  title =        {{Syntax Errors Just Aren’t Natural: Improving Error Reporting with Language Models}},
  booktitle = {Proceedings of the 11th Working Conference on Mining Software Repositories},
  year =      {2014},
  pages =     {10}