Regarding lazy ranges, @timotheecour was interested in implementing D ranges in Nim, see [https://github.com/timotheecour/vitanim/tree/master/drange/src/drange](https://github.com/timotheecour/vitanim/tree/master/drange/src/drange).
I often struggled with the same need, Nim offers genericHead but no subtype retrieval from a container by default. See my feature request [#6454](https://github.com/nim-lang/Nim/issues/6454). At the moment I would use auto, you can't do as much in type signatures (even if you use a macro the V would likely not be expanded). type Range[V] = object v: V slice: Slice[int] var r: Range[seq[int]] = Range[seq[int]](v: @[0, 10, 20, 30, 40], slice: 2..3) # r represents the range [20, 30] var x : r.v[0].type # ok: r.v[0].type is int, the type of the elements, so x is an int #If I want a generic proc to get the first element of a Range: proc first[V](r: Range[V]): auto = #ohhh, here r.v[0].type doesn't work: "undeclared field v" return r.v[r.slice.a] echo first(r) # Would be 20 Run
