Abstraction, intuition, and the “monad tutorial fallacy” (2009)

Re:Abstraction, intuition, and the “monad tutorial fallacy” ... by pharmakom on Friday October 01, 2021 @02:57AM (#28715473)

Promise<Promise<T>> is collapsed to Promise<T> automatically, which violates monad laws.

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Re:Abstraction, intuition, and the “monad tutorial fallacy” ... by eyelidlessness on Friday October 01, 2021 @11:05AM (#28719401)

What’s interesting is this seems to say the exact opposite of what the other direct response says. But I also don’t think this is exactly true.

    Promise.resolve(
      Promise.resolve('foo')
    )

At runtime is Promise<Promise<string>>. It only collapses when chained to then (or await’ed), just as in the sibling comment’s flatMap example.

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