Try 𝜑-calculus online: click here.

Try out these live examples:

1. Factorial
2. Factorial with user-defined fixpoint combinator
3. Fibonacci numbers

This is an experimental interpreter for a variant of 𝜑-calculus. Right now we implement it as a term rewriting system with the following features (see formal rules):

1. We support this syntax

   1. Objects: [x -> ^0.y, y -> [z -> ?]] (here ? stands for free attribute marker ø)
   2. Attributes: [y -> ^0.x].y.z
   3. Single named application: [x -> ?, @ -> ^0.x](x -> ^0.y) (@ stand for 𝜑 attribute)

2. By default, the interpreter will try to immediately parse and dataize an expression written in the editor.

3. If dataization fails, it will nevertheless show original term and its weak head normal form (after last reduction step).

4. At the moment, infinite recursion can hang the page and editor, — simply reload the page!

How to contribute

• Clone this repository

  git clone --recurse-submodules -j8 https://github.com/br4ch1st0chr0n3/try-phi
  cd try-phi

• Install Node.js

• Install codemirror dependencies

  npm --prefix codemirror i

• Install nix

VS Code

• Install VS Code

• Open it in try-phi folder

  code .

• Open terminal in VS Code (Ctrl+ `)

• Install stack

• Build project. Also, use this command to rebuild the project

  sh build.sh

• Install Haskell extension. It will enable linter and documentation on hover

  • "Multi cradle ..." error troubleshooting

• Open app/Main.hs and hover onto a function and check if docs appear

• Open index.html in browser, e.g.:

  firefox index.html

  • In case nothing changes, clear browser cache

• Optionally, the extension stylish-hindent for formatting the code

• Use Nix Environment Selector

• If typechecking doesn't work, reload VS Code

• You can see Haskell code's output at localhost:8080/ after

  stack run