[Haskell-cafe] Expanding do notation

Lennart Augustsson lennart at augustsson.net
Sun Jan 8 09:45:16 EST 2006

Daniel Fischer wrote:
> Cool. So let's see if I got it.
> If I have
> n <- readIO
>      ...
> mapM_ (func n) list
>      ...
> in my programme, the runtime system will/might build object code for
> func n that is then used instead of using the general code for func and 
> supplying both arguments to that?
> That'd be wow, triple wow!
> And run-time compilation is a fitting name for that.

Well, it's possible to do that.  But I don't know of any Haskell
implementation that does.  Sure, you might get a little bit of
that if func is defined suitably, like
   func 0 = foo
   func 1 = bar
   func n = baz
Implementations that have the "full laziness" property will handle
one argument at a time to a function, and may do some work with just
one argument to func.  But it's nothing like having real run-time code

	-- Lennart

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