purescript-small-ffi

This repo is a fork of pelotom/purescript-easy-ffi, which stopped publishing releases for updated Purescript versions.

Most foreign imports in PureScript follow a familiar pattern:

-- In Module.purs
foreign import foo :: Number -> Number -> Number -> Number

// In Module.js
export function foo (x) {
  return function (y) {
    return function (z) {
      return (x + y) * z; // <- the actually interesting part!
    };
  };
};

With small-ffi you can scrap all that boilerplate and write the above as:

foo :: Number -> Number -> Number -> Number
foo = unsafeForeignFunction ["x", "y", "z"] "(x + y) * z"

We can also define foreign functions returning monadic actions, by including an empty argument, e.g.

log :: String -> Effect Unit
log = unsafeForeignProcedure ["string", ""] "console.log(string);" -- note the extra ""

which is equivalent to this:

foreign import log :: String -> Effect Unit

export function log (string) {
  return function () {
    console.log(string);
  };
};

The only difference between unsafeForeignFunction and unsafeForeignProcedure is that the former takes an expression as its second argument, and the latter a statement.