Hi Serguey, I don’t know what extra functionality you require but, for what is worth, my library red-black-record features a Symbol-to-Type map . It’s implemented as a type-level red-black-tree. https://hackage.haskell.org/package/red-black-record-2.0.2.2/docs/Data-RBR.h... The map can be manipulated with the Insert, Delete and Value associated type families. Regards, Daniel Díaz

Hello cafe.

I am trying to express some environment in types to constrain program behavour. For this I need associative list of types, something along the lines of [(Symbol, *)] so that I can lookup on "variable" name and get type associated with it.

I looked into HList library but it does not provide one most generally useful way (albeit there are dozen or so of ways in there).

So where can I get most modern HList-like library? Or what should I read to get most modern HList myself?