What Color Is Your Monad

Re:What Color Is Your Monad by ackfoobar on Wednesday February 16, 2022 @10:32PM (#30369245)

The examples for for-comprehension looks very compelling. But it's painful in practice. It is still way too clunky compared to line-by-line imperative* code.

    something(a = effectfulA(), b = effectfulB())

This would be three lines in a for-comprehension. With noisy variable names.

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> We can even combine things, so F could be CorrelationId => Promise<*>

And then you need to litter your code with `liftF` and whatnot.

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*You are still doing imperative programming whether you use the language's built-in flow control or use an IO monad.

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Re:What Color Is Your Monad by shirogane86x on Thursday February 17, 2022 @06:05AM (#30371818)

small nitpick/counter example: in Haskell, you could make your example look like:

   something <$> effectfulA <*> effectfulB

<$> and <> are very common in haskell code and basically second nature to any haskeller, and that's how I would personally write it (don't know if scala has equivalents). Idris in my opinion does this even better, in Idris it would look like the following:
something !effectfulA !effectfulB -- using !-notation, or: [| something effectfulA effectfulB |] -- using idiom brackets
the two exist separately because !-notation is more general, while idiom brackets abstract _only function application_, and they desugar to map (aka <$>) and ap (aka <>), rather than !-notation which desugars to bind (aka >>=, aka <- in do blocks) I think given these they are roughly equivalent, with the added benefit (at least IMHO) that the side-effectful/monadic actions are very clearly marked even at a syntactic level

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Re:What Color Is Your Monad by ackfoobar on Thursday February 17, 2022 @12:53PM (#30376273)

Scala has overloading, currying not-by-default, optional and named parameters. Some similar stuff exist*, but they interfere with those Scala features, which I value more.

* https://eed3si9n.com/learning-scalaz/Applicative.html

I know the Haskell operators, but the Idris syntax are new to me.

BTW * has to be escaped with a \.

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Re:What Color Is Your Monad by shirogane86x on Thursday February 17, 2022 @02:39PM (#30377656)

I see that scala(z)'s operators are adapted from haskell which seems to make it quite nice, although I don't know the finer details.

Also thanks for letting me know about the escaping, sadly I can't edit the comment anymore

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