Re: Implicit reboxing of unboxed tuple in let-patterns

How about the following rule: unlifted patterns are always strict (i.e., you desugar them as if they had an explicit `!`). A pattern is "unlifted" if the type it examines is unlifted. Seems simple enough and, I think, it would do what most folks would expect. I guess a more explicit option would be to make it an error to use a lazy pattern on an unlifted type, and require programmers to manually add the `!` but I am not sure that gains much, and is more work in the compiler. -Iavor On Thu, Sep 3, 2020 at 10:38 AM Richard Eisenberg wrote:

On Sep 3, 2020, at 12:10 PM, Spiwack, Arnaud wrote:

This is all a tad tricky, I must say.

... which is one of the reasons I originally wanted one simple rule. I'm not now saying I was in the right, but it is an attractive resting point for this discussion.

To be clear, I don't think there's going to be any concrete action here without a proposal, so perhaps once this thread finds a resting point different than the status quo, someone will have to write it up.

Richard _______________________________________________ ghc-devs mailing list ghc-devs@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs