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by mrkeen 649 days ago
> Which is good, because it means we never need to write things like “await await await await await foo()

But what your describing is the actual value proposition of monad though! It's literally the construct you use to avoid excessive unwraps.

Look at the type signature of bind:

  m a -> (a -> m b) -> m b
It returns m b. Not m (m b). Not m (m (m b)).

> but they aren’t straightjacketed into the ivory tower “laws” in absolutely every edge case

In other words, you can't abstract over them. If you have libraries that manipulate monads, they will be incompatible or buggy, because they will assume (by design) behaviour that a non-monad will not live up to.

1 comments

I should not need to explain to you that the problem is when b itself is internally an (m b’). Or when it is a sum of many types, of varying m-nests.

I can assure you that JS libraries work with Promises just fine.