[Haskell-cafe] Cabal and more than one version

Duncan Coutts duncan.coutts at worc.ox.ac.uk
Wed Nov 19 04:04:01 EST 2008

On Tue, 2008-11-18 at 16:53 -0800, Jason Dusek wrote:
> In the ticket, someone says:
>     True though I suspect it looks a bit weird to the
>     uninitiated. We know to read the conditional syntax as an
>     implication constraint which can be applied in either
>     direction but I suspect many people read it in a directed
>     functional way.
>   Does that mean you don't have to actually set 'splitBase'
>   explicitly?

No, that is the point. You do not have to. The choice for the flag is
completely determined automatically by the version of the base package
that is chosen.

Because in this construct the flag choice is completely determined by
another choice by the user/environment (the version of a package) then
we do not really need a flag at all. That's why we're considering adding
some syntactic sugar for these kinds of common cases.

But it really would be just syntactic sugar. The semantics are
sufficiently powerful already.


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