[Haskell-cafe] How to "Show" an Operation?
chrisb at cs.st-andrews.ac.uk
Thu Jun 10 14:19:35 EDT 2010
Can you not just use trace?
f x = trace "in f " x
g x = trace "in g" x
That should show the order of evaluation.
On 10 Jun 2010, at 18:44, Martin Drautzburg wrote:
> On Thursday, 10. June 2010 00:08:34 Luke Palmer wrote:
>> Or just:
>> apply = val_of
>> So, to summarize: if you have something that isn't a function and you
>> want to use it like a function, convert it to a function (using
>> another function :-P). That's all. No syntax magic, just say what
>> you're doing.
> Thanks Luke
> The reason I was asking is the following: suppose I have some code which uses
> some functions, and what it primarily does with those functions is CALL them
> in different orders.
> Now at a later point in time I decide I need to give names to those functions
> because at the end I need to print information about the functions which
> together solved a certain problem. Think of my problem as "In which order do
> I have to call f,g,h such that (f.g.h) 42 = 42?".
> I don't want to change all places where those functions are called
> into "apply" style. Therefore I was looking for some idiom like the python
> __call__() method, which, when present, can turn just about anything into a
> I could change the *definition* of my original functions into "apply" style
> and the rest of the code would not notice any difference. But that does not
> really help, because in the end I want to Show something like [g,h,f], but my
> functions would no longer carry names.
> Alternatively I could associate functions with names in some association
> function, but that function simply has to "know to much" for my taste.
> The thing is, I only need the names at the very end. Throughout the majority
> of the computation they should stay out of the way.
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