[Haskell-cafe] Re: Module.T naming style

Simon Marlow simonmar at microsoft.com
Mon Jul 18 05:48:23 EDT 2005

On 15 July 2005 16:13, Malcolm Wallace wrote:

>> Hand-writing .hi files is how GHC used to work (up to version 0.29,
>> IIRC).  It's not entirely satisfactory because you can get into
>> situations where you have to 'make' several times to get to a fixed
>> point, and you can construct examples that never reach a fixed point.
> I believe, provided the hand-written boot file gives accurate type
> signatures in the first place, there is no (correctness) need to
> compile any file a second time.  At least, this is the case in nhc98
> where the interface file records only type signatures.  However,
> certainly if you /do/ re-compile, often the /sequence/ of signatures
> in the .hi file never reaches a fixpoint.

Yes - actually I was thinking of the case where you modify something in
a mutually-recursive group and recompile.  It's tempting (especially for
me, since I'm lazy) to just type 'make;make;make;make' rather than
modify any .hi files by hand.  So the .hi files don't initially contain
correct information, but you hope they converge.

It's possible by writing wrong type signatures in .hi files to diverge
instead of converge.  I can't remember the particular example right now;
IIRC it was due to Lennart.


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