Floating-point nitpicking: floor(Inf) and floor(NaN)
floor(Inf) and floor(NaN) do not appear to be defined in Standard Haskell. (They both come down to "properFraction" which is only defined for Ratio.) This differs from (for example) the Standard ML Basis Library, where it is specified that floor(Int) should raise Overflow and floor(NaN) should raise Domain. Hence Hugs and GHC do different things. Hugs returns floor(Inf) = 0 and floor(NaN) = 0 GHC returns floor(Inf) = very very large integer and floor(NaN) = even larger integer. (This is because the GHC implementation of properFraction simply ignores the case of Inf/NaN and treats the artificially high exponent encoded in those floating-point numbers as if it were a real one.) My own opinion is that Standard ML is right here and that floor(x) should raise an exception (In Haskell terms, fail) when x does not correspond to a real number.
Re: Importing instances without pangling Make
At the time of writing, I am waiting for yet another long Haskell re-make of lots of modules to complete. The frustrating thing is, that at least 90% of these remakes are actually completely unnecessary. I'm afraid I've not gone through your detailed suggestions, but in the short term, would a crude hack that I used to use with Algol68C help? For that I forced the compiler to output interface files to somewhere temporary and then used diff on them to see if there were any substantive differences. If there were none, (and compilations referring to them would therefore behave no differently) I would not copy the temporary version into the real place. All in a wrapper script around the compiler, of course. Jón -- Jón Fairbairn [EMAIL PROTECTED] 18 Kimberley Road[EMAIL PROTECTED] Cambridge CB4 1HH+44 1223 570179 (after 14:00 only, please!)
Re: Importing instances without pangling Make
Suppose that B had imported C only to export it again (either by listing it in the export list, or not having any export list at all). Wrong. If B imports C and has no export list, nothing from C is re-exported, only definitions from B itself, with the single exception of C's instance decls. Regards, Malcolm
Re: Importing instances without pangling Make
George Russell wrote: This scheme is not the cleverest that could be devised. For example it is still necessary to recompile whole chains of modules if you add an import declaration. (Not to a system library, imports from those are counted as "stable" in GHCs and my system.) To fix this you would need to keep more information in the .hi file. Actually we can catch most of these cases too. Alter algorithm A so that if we have no changes to instances declarations in this file, the version numbers in directly imported modules are all the same, and the only change is that we import some modules we didn't import before, then only bump the version number if the import leads to new modules being imported which contain instance declarations. I think you can compute this at very close to zero cost at the start of compilation, when you are doing the imports.
Re: Importing instances without pangling Make
Malcolm Wallace wrote: Wrong. If B imports C and has no export list, nothing from C is re-exported, only definitions from B itself, with the single exception of C's instance decls. OK, but this has no influence at all on my suggestions except to make them work slightly better.
Re: Importing instances without pangling Make
Jon Fairbairn wrote: I'm afraid I've not gone through your detailed suggestions, but in the short term, would a crude hack that I used to use with Algol68C help? No, fraid not. GHC already does this hack anyway. Algol68C didn't have interface declarations. Still, nice to find someone else who remembers it.
RE: Importing instances without pangling Make
Seems like you're not using -recomp. --sigbjorn -Original Message- From: George Russell [mailto:[EMAIL PROTECTED]] Sent: Friday, February 25, 2000 8:53 AM To: [EMAIL PROTECTED] Subject: Importing instances without pangling Make
Re: Importing instances without pangling Make
Sigbjorn Finne wrote: Seems like you're not using -recomp. No I'm not. What about documenting it somewhere?
Re: Importing instances without pangling Make
Sven Panne wrote: George Russell wrote: [...] Supposing you now make a change to C. For example, suppose you add a line pangle = "pangle" to the end of C, and add "pangle" to the list of exports from C. Then you recompile C. You will find that C.hi now has a new version number "2". Strange, this is not the case with my version of GHC (from the CVS repository two days ago). Ooops, too quick! :-} I didn't read closely enough and didn't add `pangle' to the export list... Anyway, in my experience -recomp plus explicit import lists are a big gain in recompilation time. Cheers, Sven -- Sven PanneTel.: +49/89/2178-2235 LMU, Institut fuer Informatik FAX : +49/89/2178-2211 LFE Programmier- und Modellierungssprachen Oettingenstr. 67 mailto:[EMAIL PROTECTED]D-80538 Muenchen http://www.informatik.uni-muenchen.de/~Sven.Panne
Re: Importing instances without pangling Make
George Russell wrote: Sigbjorn Finne wrote: Seems like you're not using -recomp. No I'm not. What about documenting it somewhere? I take that back. I AM using it in the big program I mentioned, but I still get huge swathes of unnecessary compilations. Maybe it needs to be still cleverer.
RE: Importing instances without pangling Make
George Russell [EMAIL PROTECTED] writes: Sigbjorn Finne wrote: Seems like you're not using -recomp. No I'm not. What about documenting it somewhere? I think that's a fine suggestion which GHC HQ will probably do something about (Section 3.7.4 doesn't actually mention it by name.) Re: recomp checker, Patrick Sansom wrote up a paper about it (see http://www.dcs.gla.ac.uk/~sansom/ ) - Simon has improved and modified the story a bit since then, but the underlying idea is still very much the same. --sigbjorn
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My Name is William Uruguay Montevideo South America Y have a lot of manuals and program about Hakell and more Y like verimach y have Hugs and few manuals printed but 20 and more time y have dowload ghc but dont work it It is posibilite to have with a cdroom ym pay for these veri good program my email is [EMAIL PROTECTED] My adrres is William Artifoni Alto Peru 1928 (Malvin) Ap 1 Montevideo Uruguay ok by by
