[Haskell-cafe] Define a module in multiple files
Roel van Dijk
vandijk.roel at gmail.com
Mon Nov 30 13:07:14 EST 2009
On Mon, Nov 30, 2009 at 6:27 PM, Ozgur Akgun <ozgurakgun at gmail.com> wrote:
> Nice idea, but this way you still need to modify the single module which
> glues them alltogether.
> I wanted to allow the users of the module add some functionality to the
> module itself.
I don't think that is possible.
But a user could easily create a new module which offers all the
functionality of the old one plus the user's own additions.
-- Some library module
module A (a) where
a = 1
-- Custom module written by user
module UserModule (module A, myFunction) where
userPrint = print
-- Program which uses UserModule
module Main where
main = userPrint a
The idea is that UserModule re-exports all symbols from module A. So
importing UserModule brings all symbols from A in scope and possibly
extra symbols defined in UserModule itself.
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