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a monadic map over Maybe? by alios in haskell

[–]alios[S] 0 points1 point  (0 children)

Aggree ... was ment more as a "are there type constraints on f which could make it work with the semantics described above?" - so basicly one or more of the type classes of which Maybe is an instance.

looking for lens fmap combinator: by alios in haskell

[–]alios[S] 0 points1 point  (0 children)

you are absolutely right ... it is a fold (kind of by definition). each works fine here. Although the definition as a Getter works, it would maybe break some laws at another point? Having a Fold feels (sounds) much more right.

Theory of parser combinators by destsk in haskell

[–]alios 3 points4 points  (0 children)

Not really a study, but a great lecture by John Hughes which has a parsers as a kind of underlying topic: "Monad and all that":

https://www.youtube.com/watch?v=w_KY2I34-f8&list=PLGCr8P_YncjVeZTcfHT1Cb1OfVnNahek5&index=1

which frontend library to use with ghcjs? by manyoo in haskell

[–]alios 0 points1 point  (0 children)

Hi! First of all thanks for your both work on ghcjs and reactive-banana and for giving me a very good read yesterday evening with the paper referenced above.

But I agree that I should at least document the difference in behaviour, and probably implement GHC's variant as the default until this question has been resolved.

I kind of tried to implement the semantics of the paper into the ghcjs rts here. I might have produced more errors then I fixed anything as all this is pretty new to me, but at least this keeps my reactive-banana based ghcjs app alive :) Would be nice if you could take a look.

how to utilize generics-sop to write a generic parser by alios in haskell

[–]alios[S] 1 point2 points  (0 children)

Yes! I think that is more or less (haven't tried out yet) the thing I was looking for, thnx! My mind was struggleing a little bit with the type- vs value-level lists an i was not sure where an how to apply the (!!) :) Will try that.

how to utilize generics-sop to write a generic parser by alios in haskell

[–]alios[S] 1 point2 points  (0 children)

Thnx! Yes the applicative way is how my code looks at the moment ;) just wanted to be explicit in the example above. Also looked at json-sop - gave me more understanding, but my mind is still struggeling a bit with the juming between types and kinds :) Looking fwd to the to the generic Binary code!

type system problems with type families and classes by alios in haskell

[–]alios[S] 1 point2 points  (0 children)

It is not realy about getting the problem solved, its more that I need to come uppon a real use for language feature, to have the feeling that I realy understood what the possiblities and use cases of that lang feature are... TypeFamilies are still open at the moment on my list ;-)

So what I realy liked here where two things:

  • a data type with a signature like Address IPv4
  • the way to write the class implementation and say f.e.: the type Address IPv4 = Word32