[Haskell-cafe] How to dynamic plan in Haskell?

[Magicloud Magiclouds]

I see. Did not got the filterM part in mind. Thanks.

On Sat, May 18, 2019 at 1:48 PM Francesco Ariis <fa-ml at ariis.it> wrote:
>
> Hello,
>
> On Sat, May 18, 2019 at 12:33:00PM +0800, Magicloud Magiclouds wrote:
> > I solved the question. But I could not figure out a FP style solution.
> >
> > Question:
> >
> > 1 - 9, nine numbers. Show all the possible combinations that sum up to
> > 10. Different orders are counted as the same.
>
> A possible solution takes advantage of powersets with the [] Monad.
>
>     λ> :m +Control.Monad
>     λ> f cs = filterM (\x -> [True, False]) cs
>     λ> filter ((==10) . sum) (f [1..10])
>
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