have traverse take a type representative rather than an "of" function #220
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| A value which has a Traversable must provide a `traverse` method. The `traverse` | ||
| method takes two arguments: | ||
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| u.traverse(f, of) | ||
| u.traverse(A, f) |
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So HAPPY right now that the order was finally switched. 🎈 🍰 🎉 🌈 🦄
EDIT:
Well could potentially, Maybe be switched.
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I didn't like the old order, but I couldn't justify a breaking change to scratch my itch. But if we're making a breaking change anyway we can flip the parameters while we're at it. :)
Out of interest, why do you prefer the new order?
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Well for me, the TR is the more stable of the two parameters. It defines a classification if you will.
I could have a whole family of a -> f b functions, but they all tie to one f.
So using some point-free traverse, it just seems natural to fix that parameter and get a function back for that fixed Applicative. If that makes sense?
EDIT:
(I am not really that good at this stuff, so my reasoning may be 💯 🗑)
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I'm with you 💯 per cent. :)
| const u = [x]; | ||
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| const a = u[traverse](Id[of], Id[of]); |
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I think in this old version, it should have been:
const a = u[traverse](Id[of], Id[of]);
const b = t(u);and because of that, new version should be like this:
const identityʹ = T => eq => x => {
const u = [x];
const a = u[traverse](T[of], T);
const b = T[of](u);
return eq(a, b);
}and on caller side:
test(traversable.identity(Id)(equality))
| Array.prototype[fl.map] = Array.prototype.map; | ||
| Array.prototype[fl.map] = function(f) { | ||
| return this.map(x => f(x)); | ||
| }; |
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In addition to mutating globally defined prototypes and featuring bugs such as the one above, this file contains a hack for Array#fantasy-land/equals, convincing me that the laws do not belong in this repository (#174). We really need sanctuary-type-classes to avoid monkey patching.
Sanctuary's property-based tests are really nice. See, for example, Functor.js. I'd like to move these tests to fantasyland/fantasy-laws and remove the laws directory from this repository. :)
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Will do. :)
Sanctuary is missing some of the laws, as we've only defined tests for those applicable to Maybe and/or Either. sanctuary-js/sanctuary#323 adds tests for Alt, Plus, and Alternative. Once that pull request has been merged I'll create fantasyland/fantasy-laws and submit an initial pull request.
davidchambers
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Closes #207
I intend to merge sanctuary-js/sanctuary-type-classes#28 regardless, but it would be nice to make this improvement here too. :)