Switch from BatEnum to Seq

[karoliineh]

A try on switching to the more standard Seq.t in Enum instances where possible as proposed in #1437

Some things that I noticed:

• Enum.cartesian_product is called product in Seq
• Enum.uncombine is called unzip (or split) in Seq
• Enum.fold is called fold_left in Seq
• There is no corresponding function to Enum.uniq in Seq
• There is no to_seq in BatHashtbl
• There is no to_seq_keys in BatHashtbl as in the Ocaml standard library Hashtbl

TODO

• Fix Gobview.
• Wait for Add reset, find_opt and Seq functions to BatHashtbl ocaml-batteries-team/batteries-included#1133 to release? Release 3.9.0 ocaml-batteries-team/batteries-included#1135
• Bump OCaml lower bound to 4.14? Many Seq functions are that new. (Bump OCaml lower bound to 4.14 #1448)
• Merge Upgrade batteries to version 3.9.0 gobview#51.

[michael-schwarz]

What is still missing here?

[sim642]

What is still missing here?

A new batteries release would allot switching many Hashtbl-related places: ocaml-batteries-team/batteries-included#1135.

[sim642]

Batteries 3.9.0 has now been released, so that should allow porting some of the previously problematic places as well.

[sim642]

There's now a conflict with PR #1623 which added a component to IntDomTuple.

[michael-schwarz]

@karoliineh: Is this now ready for review?

[karoliineh]

@karoliineh: Is this now ready for review?

Yes

[michael-schwarz]

Should we add semgrep rules to prevent adding new code that uses BatEnum?

[sim642]

Should we add semgrep rules to prevent adding new code that uses BatEnum?

Yes, although I just tried and after these changes the rule still seems to find remaining instances.
Either some couldn't (yet?) easily be switched over, or they have been introduced during the year this has been open.
We should merge this now and then someone can perhaps do another pass. I'll put my semgrep rule in a new draft PR.