Investigate IsList instance

[ilyakooo0]

I think it might be possible to define an IsList instance for matrices.

[bolt12]

It would be interesting indeed! Do you have in mind something simple such as using the already provided `toList`/`fromLists` functions?

…

On Sun, 31 May 2020, 19:02 iko, ***@***.***> wrote: I think it might be possible to define an IsList <https://hackage.haskell.org/package/base-4.14.0.0/docs/GHC-Exts.html#t:IsList> instance for matrices. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#16>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AE2SULNDVCYE47YU3ETKIALRUKLSRANCNFSM4NPIGORA> .

[leftaroundabout]

The problem with an IsList instance is that it would have to generate either a runtime error or even worse unexpected behaviour when supplying a list of wrong length. There is some discussion in a GHC issue concerning proper vector literals. I suggested adding the possibility to constrain the allowed length for IsList instances, which would make it suitable also for this library.

class IsList l where
  type Item l
  type AllowedLength l (n :: Nat) :: Constraint

and am thinking about submitting this as a GHC proposal.