MACwMP

Monadic array comprehension with meta programming in JS

What's this?

Implementation of Haskell-like array comprehension, probabily in the most eccentric way.

$[x + y | x <- [1, 2, 3], y <- [4, 5, 6], x * y % 2 === 0]
// -> [ 5, 7, 6, 7, 8, 7, 9 ]

How does it work?

1. With Sweet.js, define a macro for array comprehension operator $.
2. The macro builds array comprehension into async/await syntax.
3. Replace global Promise with CArray (stands for comprehensible array)
   • Async/await is like do expression in Haskell
   • Now it executes monad comprehension for array
4. Build async/await syntax into Promise chaining
   • Do expression in Haskell can also be transformed into bind chaining
5. Profit!

Run examples

npm run build -- examples/simple.js
node dist/simple.js

You can see each build step with each build script.

# build macro
./scripts/build-macro.sh examples/simple.js
cat dist/simple.macro.js

# build async/await into Promise chaining with Babel
./scripts/build-babel.sh dist/simple.macro.js
cat dist/simple.babel.js

# concat monad stuff
./scripts/build-monad.sh dist/simple.babel.js
cat dist/simple.js

License

MIT