One potential difference between the two is that the current behavior
allows the `Main` module to import `main` from another module, while the
new behavior would fail in that case.
For example, a file that has only a single line:
import SomeOtherModule(main)
This still seems like a fairly unusual corner case (with an obvious work
around), so I don't think it matters much, but I thought I'd mention it so
that we are aware of it.
On Tue, May 16, 2017 at 7:18 AM, Joachim Breitner
Hi,
a very small proposal to be considered for Haskell':
Currently, the report states
An abbreviated form of module, consisting only of the module body, is permitted. If this is used, the header is assumed to be ‘module Main(main) where’.
I propose to change that to
An abbreviated form of module, consisting only of the module body, is permitted. If this is used, the header is assumed to be ‘module Main where’.
The rationale is that a main-less main module is still useful, e.g. when you are working a lot in GHCi, and offload a few extensions to a separate file. Currently, tools like hdevtools will complain about a missing main function when editing such a file.
It would also work better with GHC’s -main-is flag, and avoid problems like the one described in https://ghc.haskell.org/trac/ghc/ticket/13704
I don’t see any downsides. When compiling to a binary, implementations are still able to detect that a Main module is not imported by any other module and only the main function is used, and optimize as if only main were exported.
Greetings, Joachim
-- Joachim “nomeata” Breitner mail@joachim-breitner.de • https://www.joachim-breitner.de/ XMPP: nomeata@joachim-breitner.de • OpenPGP-Key: 0xF0FBF51F Debian Developer: nomeata@debian.org _______________________________________________ Haskell-prime mailing list Haskell-prime@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-prime