Hi,
if param1 then sp = f1 . f2 . f3 else sp = f1 . f3
If you have many situations like these, i.e. where one or several
components are conditional, you can define a function
when True f = f
when False _ = id
And now you can define sp like this:
sp = f1 . when param1 f2 . f3
Regards,
Jonas
On 24 August 2011 14:35, dokondr
Hi, What is the Haskell way to compose functions in run-time? Depending on configuration parameters I need to be able to compose function in several ways without recompilation. When program starts it reads configuration parameters from a text file. For example, I have three functions, f1, f2, f3, each doing some string processing. I need to support two configurations of string processors :
if param1 then sp = f1 . f2 . f3 else sp = f1 . f3
I'd like to avoid 'if' somehow and instead use some declarative way to specify code to run in external configuration file. In other words I need some easy tools to create mini DSLs without all the efforts usually involved with implementing full-blown DSL.
Thanks, Dmitri
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