[Haskell-cafe] Solving the configuration problem with parametrized modules
mail at joachim-breitner.de
Thu Sep 8 12:00:57 CEST 2011
Am Donnerstag, den 08.09.2011, 09:21 +0200 schrieb Paul R:
> Joachim> point taken, if you are already building on a transformer
> Joachim> stack, adding yet another layer is not a problem. I’m having
> Joachim> mainly pure code in mind.
> I think we need an other word than "pure" here. Usually, we understand
> "pure" as "always producing the same result when given the same
> parameters". Here, "always" really means "always", and does not depend
> on the run-time context of the program. So obviously, a really pure
> function can't use side-effect run-time constants.
> IIUC, what you want is "run-time qualified" functions, or functions that
> "In the scope of a run, always produce the same result when given the
> same parameters". Is that right ?
yes, although I understand “pure” as that, e.g. always within one run of
the program. This is in line with some other “constants” as those in in
GHC.Constants and System.Info in base.
What breaks if we allow functions to be pure only within one run of the
Joachim "nomeata" Breitner
mail at joachim-breitner.de | nomeata at debian.org | GPG: 0x4743206C
xmpp: nomeata at joachim-breitner.de | http://www.joachim-breitner.de/
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