elm-lang/virtual-dom/VirtualDom.js, F2(), F3(), A2(), A3()

[jeff...@gmail.com]

The source code for Elm virtual-dom contains a file VirtualDom.js

In this file are calls to functions F2(), F3(), A2(), A3().

I can't find where these functions are defined or what they do, and I would like to know.

[OvermindDL1]

https://github.com/elm-lang/elm-make/blob/master/src/Pipeline/Generate.hs

In the Elm core, they are just wrappers like:

```javascript

function F2(fun)

{

  function wrapper(a) { return function(b) { return fun(a,b); }; }

  wrapper.arity = 2;

  wrapper.func = fun;

  return wrapper;

}

function A2(fun, a, b)

{

  return fun.arity === 2

    ? fun.func(a, b)

    : fun(a)(b);

}

```

[Joey Eremondi]

https://github.com/elm-lang/elm-make/blob/master/src/Pipeline/Generate.hs

They get bundled into the Runtime of a generated Elm file.

They allow for currying of JS functions. F2 takes a 2-argument JS function and returns a curried version of it (takes one argument, and returns another function taking one argument).

A2 is for applying two arguments to a curried function.

You need to use these when returning functions to Elm, or calling Elm functions, since they're meant for dealing with the function format Elm uses internally.

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[jeff...@gmail.com]

Thanks.