Instructions

• Install opam (these instructions assume opam version 2+). If you are using Windows, it is highly recommended that you use Windows Subsystem for Linux (WSL). More detailed instructions on how to install opam on WSL can be found here
• Create a new switch using OCaml 4.14.0 (you can replace "homework" with any switch name you'd like; it's likely the code will work with other versions but we have only confirmed it works in 4.09.0 and 4.14.0)

opam init
opam switch create homework 4.14.0
eval $(opam env)

• Install dependencies:

opam install core dune merlin ounit2

• Build with make. This will create symlinks to four binaries. They are:

  • while: a While interpreter
  • w3a: a While3addr interpreter
  • compile: a While to While3addr compiler

  All of these binaries take input on stdin and output on stdout (i.e., you can run a While program by running ./while < program.while, not by passing a file as input).

Python

Python requires a version of at least 3.10 to use (the project makes use of the new match statement). It also needs z3 to solve constraints. Install z3 via

pip3 install z3-solver

The important python3 file entrypoints are src/repair/repair.py and src/repair/interpreter.py repair.py takes two arguements, testPath and outPath, testPath informs us of the Test Suite and outPath outputs a new program that passes all the test cases. Interpreter.py runs a w3a program along with some given inputs. python3 src/repair/interpreter file args. The file is a path to the file containing a valid a w3a program. args is either an int for an integer argument, or a space separated list of integers to denote a list arguement. This implies that a w3a program only has a single input.

File specification for writing a Test suite will loook like

buggyProgPath input1 : output1 input2 : output2 inputn : outputn

Run python src/repair/repair.py filePath outPath will try to fix file at buggyProgPath and generate a program to try to pass the three tests given in the file. The generated program is located at outPath.

Program Report Gives moere detail on the research in automatic program repair, the specification of the project, tradeoffs, and how to reproduce the setup.

Resources

• You might be interested in reading Adam Chlipala's overview of the philosophic differences between OCaml and SML: http://adam.chlipala.net/mlcomp/
• This page has a nice side-by-side comparison of the syntax of SML and OCaml: https://people.mpi-sws.org/~rossberg/sml-vs-ocaml.html
• We are using the Core library maintained by Jane Street as it is more feature-rich than the OCaml standard library. The API documentation on that page should be useful.
• If you're using Vim or Emacs, Merlin is a very useful tool that adds features like autocompletion and function signature lookup. The Merlin GitHub page will help you get set up.
• If you're using Emacs, Tuareg mode is a good editing mode.
• OCaml is a compiled or interpreted language, so it can be run in a REPL. You can use the standard OCaml REPL, but we recommend UTop, which can be installed with opam install utop.
• The official OCaml site has a lot of resources for learning OCaml.
• Real World OCaml is a great book for learning OCaml and is available free online.