Add Future.bichain #411
Add Future.bichain #411
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## master #411 +/- ##
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Coverage 100% 100%
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Files 45 46 +1
Lines 1957 1976 +19
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+ Hits 1957 1976 +19
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I don't know to which algebraic properties for the left branch of bichain you're referring to. I was also thinking of adding a |
test/prop/0.algebra.js
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| property('bichain left identity', _x, _fm, function (x, f){ | ||
| return eq(bichain(f)(reject)(reject(x)))(f(x)); | ||
| }); |
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I think this is the wrong interpretation of "left identity". I don't think it means "identity on the left branch", but rather it exists because for Monad, you can't test identity in a single equation. This also explains your confusion:
I don't know to which algebraic properties for the left branch of bichain you're referring to.
Once you have changed left identity to apply to the right branch, you need separate tests for testing left and right identity on the left branch.
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Essentially what we're testing is that chain (resolve) is the identity function for m. So what you should be testing is that bichain (reject) (resolve) is the identity function for m.
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In the chain equations, this property is verified in two steps:
left | chain (f) (resolve (x)) = f (x)
right | chain (resolve) (m) = mThere was a problem hiding this comment.
So for bichain it should probably look like:
left | bichain (f) (g) (reject (x)) = f (x)
left | bichain (f) (g) (resolve (x)) = g (x)
right | bichain (reject) (resolve) (m) = mThere was a problem hiding this comment.
I don't understand now the difference between right and left identity. I always thought it was related to the branches. In any case, from your comments I have changed the code and hopefully it is right now.
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I don't really understand the naming of the assertions either. Maybe the idea was something like: "identity as asserted from the left side" and "identity as asserted from the right side". Maybe we can get @puffnfresh to recall how he got to the naming, and whether our interpretation of it is right.
I think of the two assertions as:
- "given that
chain (f) (resolve (x))is the equivalent off (x)"; (left identity) - "
chain (resolve) (m)should be the equivalent ofm". (right identity)
But I might be wrong. The code looks good to me now, but let's wait a bit and see if Brian will respond :)
Close #332