On Tuesday 23 March 2004 11:36, Graham Klyne wrote: > I think you're a rather stuck with the "temporary variables" (which they'= re > not really), but it might be possible to hide some of the untidiness in an > auxiliary monadic function.
That seems to be the common suggestion: write my own visitors.
I'm just surprised that there isn't a more elegant mechanism for getting=20 interoperability between monadic and non-monadic functions. The current=20 state of affairs just seems awkward. =20
[Warning: quasi-rant]
Caveat: I'm not smart enough, and I don't know enough, to criticize Haskell= ,=20 so please don't misconstrue my comments. To quote Einstein: "When I'm aski= ng=20 simple questions and I'm getting simple answers, I'm talking to God." I=20 simply mistrust, and therefore question, systems where simple things are=20 overly involved.
The standard explaination about why monads are so troublesome always sounds= =20 like an excuse to me. We have monads, because they allow side-effects. Ok= =2E =20 If programs that used side effects were uncommon, I'd be fine with them bei= ng=20 troublesome -- but they aren't. Maybe it is just me, but my Haskell progra= ms=20 invariably develop a need for side effects within a few tens of lines of=20 code, whether IO, Maybe, or whatnot. And I can't help but think that=20 language support to make dealing with monads easier -- that is, to integrat= e=20 monads with the rest of the language, so as to alleviate the need for=20 constant lifting -- would be a Good Thing.
I'd make one further point in response... I don't think the "heavy lifting" here is because of Monads in general: some Monads (Maybe, lists, etc) mix very easily with pure functional code. I think it's the IO Monad in particular: here you are creating interactions between two fundamentally different environments: the real-world, which is fundamentally stateful and non-referentially-transparent, and mathematical functions that are quite the opposite.
Hmmm. Could I say that Haskell requires "heavy lifting"?
:-)
#g
------------ Graham Klyne For email: http://www.ninebynine.org/#Contact
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