similar as Mathias's thought, I would see the following approach more appropriate: boost::accumulative_function< r(a1, a2, ...)> because essentially, the currying is to call same thing repeatedly and remember the result each time. cheers, Jinqiang ZHANG On Wed, Aug 24, 2011 at 7:21 AM, Mathias Gaunard < mathias.gaunard@ens-lyon.org> wrote:
On 08/23/2011 11:15 PM, Mathias Gaunard wrote:
On 08/23/2011 09:38 PM, Eric Niebler wrote:
After playing around with functional languages, I've come to envy how easy they make it to curry functions. Call a 2-argument function with 1 argument and you get a function that takes 1 argument. Pass another argument and it evaluates the function. Simple. In contrast, C++ users have to use binders, which are not as nice.
On a lark, I implemented a wrapper that turns any TR1-style function object into a "curryable" function object (attached). Successive function call invocations bind arguments until enough arguments are bound to invoke the wrapped function. With it you can do the following:
curryable<std::plus<int> > p; auto curried = p(1); int i = curried(2); assert(i == 3);
Is there any interest in such a thing?
It could be argued that Phoenix actors should be doing this.
I also asked a lot of time ago for an easy function to turn a pfo into a phoenix actor, which I think would make phoenix much more ubiquitous.
assuming that function was called lazy, and Phoenix did currying automatically, you could do
int i = (lazy(std::plus<int>)(1) + 4)(3)
Sorry, this should have been
int i = (lazy(std::plus<int>())(1) + 4)(3) of course.
And I remember why Phoenix doesn't do currying: that's because that only works with monomorphic function objects.
Detecting and propagating monomorphism could be nice though. It could eventually provide better error messages, faster compilation times, and automatic currying on monomorphic function objects.
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