Consider better namespacing?

[hyphenrf]

Right now we use Seq.* namespace unhygienically, which as a pro/con allows users to override with their custom Seq module.
An alternative would be to introduce better hygiene (maybe Ppx_seq.Stdlib.Seq.*?) to make overriding the module harder, and the behaviour more consistent.
The problem with this is probably that now ppx_seq becomes a runtime, not a compile time, dependency.

This is open for suggestions as my experience with large OCaml codebases is Seq.Nil.

[hyphenrf]

More things that are currently unhygienic:

• +, -, succ, compare (on purpose) ¹
• =, < in use with compare (fixed)
• inf, fin in generated code for sequences (fixed) ²

Footnotes

1. The alternative is Haskell's approach, requiring an implementation to an enum interface where impl details are irrelevant.
   One problem with this is that we want the default behaviour with int to be as frictionless as possible..
   So there must be a way to provide a default int implementation if we go this route. ↩

2. There must be ways more experienced ppx authors make sure the names in their generated code never clash with the names in the program. ↩