On Fri, 4 Jun 2021, Olaf Klinke wrote:
On Thu, 3 Jun 2021, MigMit wrote:
At this point I'm not sure how it is different from a simple function. The HoleyMonoid example
holey = now "x = " . later show . now ", y = " . later show
when paired with 'argn'-style variables essentially becomes
holey arg1 arg2 = "y = " ++ show arg2 ++ "; x = " ++ show arg1
So, what kind of syntax do you have in mind?
What I'm after is documentation of n-ary functions. Suppose
f :: a -> a -> Maybe a f arg1 arg2 = if arg1 < arg2 then Nothing else Just arg2
The docstring of f should be a function that, given descriptions of the arguments, generates a description of the result. E.g.
doc_f = "if " <> arg1 <> " is smaller than " <> arg2 <> " then Nothing else Just " <> arg2
Say you have concrete arguments which are already tagged with a description: x :: (String,a) y :: (String,a)
One could then have an operator <%> that acts like function application but at the same time takes care of documentation:
func desc_f f <%> x <%> y :: (String,c)
Here 'func' is an operator that translates the hypothetical docstring type into a real function.
I don't fully understand the problem, but for me it sounds like an Applicative functor: data T a = Cons String a x,y :: T a func desc_f f <*> x <*> y :: T c