#725: Distinguish speculative and required build-depends upper bound ---------------------------------+------------------------------------------ Reporter: ezyang | Owner: Type: enhancement | Status: new Priority: normal | Milestone: Component: cabal-install tool | Version: 1.6.0.3 Severity: normal | Keywords: Difficulty: unknown | Ghcversion: Platform: | ---------------------------------+------------------------------------------ Comment(by wk):
Recording this extra information in the context of hackage is much easier.
I don't understand exactly what you mean, but it seems to exclude recording this "extra information" for unpublished packages and local developments?
For one thing it can be discovered automatically.
You can discover automatically whether it compiles. You cannot, in general, discover automatically whether it works correctly.
Adding this information to .cabal files is more tricky, we need a syntax for it and users have to specify it.
I don't think the syntax question is tricky --- if you know the semantics you want to enable, you have tons of options. One particularly easy option would interpret the current ranges as establishing mappings to {{{KnownToWork}}}, and add a separate notation (perhaps using a {{{!}}} prefix) to establish mappings to {{{KnownToBreak}}}. Versions not mentioned in either would be interpreted as being mapped to {{{UnKnown}}}. I estimate that most currently-listed excluded upper bounds are intended to mean {{{UnKnown}}} and not {{{KnownToBreak}}}. Therefore, this would even be backwards-compatible. (The semantics of sequences of such positive or negative ranges would most naturally be {{{Map.foldWithKey Map.insert}}}, that is, a right-biased version of {{{Map.union}}}.) If {{{UnKnown}}} gives rise only to a warning instead of to a refusal to even attempt compilation (as it does now), that will make it also much easier for package authors to be honest about old versions they did not check against. Wolfram -- Ticket URL: http://hackage.haskell.org/trac/hackage/ticket/725#comment:5 Hackage http://haskell.org/cabal/ Hackage: Cabal and related projects