#179: support GHC's main-is extension ----------------------------+----------------------------------------------- Reporter: duncan | Owner: Type: enhancement | Status: new Priority: low | Milestone: _|_ Component: Cabal library | Version: 1.2.2.0 Severity: normal | Resolution: Keywords: | Difficulty: normal Ghcversion: 6.4.2 | Platform: Linux ----------------------------+----------------------------------------------- Comment (by cjs): Well, first of all, I think it's a bad idea that Cabal has an option with exactly the same name as a GHC option that ostensibly does something similar, but with different semantics. That said, the best we can do is something to make it more obvious that the semantics are different, unless we sacrifice backward compatability. As to why people want to use this, I can think of a couple of good reasons. One is that some people like to build an entire source tree into an object tree directly with ghc, in which case you cannot have multiple modules named Main (at least not simply). The second is that it can save an extra file, or six or eight, if you've got that many command-line programs to generate. So is there a good reason to refuse to support this, for those ghc users that work this way? It seems to me it would be easy enough to extend the syntax of this option slightly to allow specifying the module and/or function to use as main. Perhaps something along the lines of "main-is: Foo.hs Foo.foo". In other words: main-is: Foo.hs file Foo.hs, module Main, function main main-is: Foo.hs Bar file Foo.hs, module Bar, function main main-is: Foo.hs baz file Foo.hs, module Main, function baz main-is: Foo.hs Bar.baz file Foo.hs, module Bar, function baz This isn't quite compatable with ghc's main-is option, but it's close, at least, and maintains backward compatability with current main-is behaviour. Slightly more friendly might be to have the module name default to the module name declared inside the source file, if that's not too much work. -- Ticket URL: http://hackage.haskell.org/trac/hackage/ticket/179#comment:4 Hackage http://haskell.org/cabal/ Hackage: Cabal and related projects