[Haskell] "global variables" and code optimization

Jan-Willem Maessen - Sun Labs East Janwillem.Maessen at Sun.COM
Fri Sep 10 09:34:42 EDT 2004

Keith Wansbrough wrote:
>... [Bernd discusses his problems using unsafeperformIO to generate unique names, and Keith responds]
> Why not just thread (newLabelNr :: Int) through your code to the places that need it?  If you do this with other things too, then put them in a record.  This is a kind of "poor-man's" state monad.

Alternatively, if you're threading something through your program, why 
not thread a splittable supply of new names?  You can use the supply 
to generate fresh identifiers directly, and it all behaves purely 
functionally.  There's code for unique supplies here:


Look down the page for "Arbitrary Splittable Supplies".

-Jan-Willem Maessen

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