Add is.convert to convert a test to a function

[wooorm]

Useful for reuse.

Closes GH-5.

[ChristianMurphy]

Code looks good,
I'm not sure I follow how it's intended to be used.
Would it look like

function test () {/* some test*/}

const tester = convert(test);
tester(/* a node */);

?

[wooorm]

@ChristianMurphy Thanks for asking that question, it’s in my head, but before I answer I’d like to make sure that you saw the docs (https://github.com/syntax-tree/unist-util-is/blob/2ac6b804c42eba6cce804ff5984a71e192836aee/readme.md#isconverttest) and that they aren’t useful enough?

[ChristianMurphy]

I saw that
The comment:

Create a test function from test, that can later be called with a node, index, and parent

Is what made me think it might be a partially applied function.

[wooorm]

The idea is that it would save a little bit of overhead if you know you’re values (node, index, parent) are correct. That it can be used in utilities like unist-util-visit-parents that use that test a lot.

The example you provided in #7 (review) is correct, and:

Is what made me think it might be a partially applied function.

Yup, it’s creating a function from any valid test value, that is thus “applied”

[ChristianMurphy]

Cool, makes sense, just double checking