[Haskell-cafe] Does Haskell have this SML syntax?

Galaxy Being borgauf at gmail.com
Fri Mar 26 05:26:47 UTC 2021

I'm sure you've answered my question, but I'm too much of a beginner to
fathom it. If you could explain, that would be great, but I could also go
off and try to grok it myself. Again, thanks.

On Fri, Mar 26, 2021 at 12:09 AM Ignat Insarov <kindaro at gmail.com> wrote:

> Hello Galaxy Being!
> You can do this:
>     module Y where
>     substitute ∷ (α → Bool) → (α, [α]) → [α]
>     substitute predicate = \ thing → case thing of
>       (_, [ ]) → [ ]
>       (substitution, (x: xs)) →
>         let remainder = substitute predicate (substitution, xs) in
>           if predicate x
>           then substitution: remainder
>           else x: remainder
> It is even nicer since we can factor out the common part of the `if`
> block into a `let … in`. You can also enable the `LambdaCase` language
> extension and it will let you elide the `thing` thing.
> I am not sure if this is what your question is really about… In
> principle, of course Haskell has currying. Actually, functions are
> usually written in curried form in Haskell. Please let me know if I
> missed the substance of your question!
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