On 07/27/2014 10:48 AM, bearophile wrote: > In std.functional there is a curry(), that looks more like a partial > application. > > In the Python land I've recently seen a library for a more functional style > of coding: > https://pypi.python.org/pypi/PyMonad/ > > I don't like for Python most of the stuff in that PyMonad library, but two > bits look nice. I quote them here: > > << > > @curry > def add(x, y): > return x + y > > @curry > def func(x, y, z): > # Do something with x, y and z. > ... > > The above fuctions can be partially applied by passing them less than their > full set of arguments: > > add(7, 8) # Calling 'add' normally returns 15 as expected. > add7 = add(7) # Partial application: 'add7' is a function taking one > argument. > add7(8) # Applying the final argument retruns 15... > add7(400) # ... or 407, or whatever. > > # 'func' can be applied in any of the following ways. > func(1, 2, 3) # Call func normally. > func(1, 2)(3) # Partially applying two, then applying the last > argument. > func(1)(2, 3) # Partially applying one, then applying the last two > arguments. > func(1)(2)(3) # Partially applying one, partially applying again, then > applying the l > > > > Curried functions can be composed with the * operator. Functions are applied > from right to left: > > # Returns the first element of a list. > @curry > def head(aList): > return aList[0] > > # Returns everything except the first element of the list. > @curry > def tail(aList): > return aList[1:] > > second = head * tail # 'tail' will be applied first, then its result > passed to 'head' > second([1, 2, 3, 4]) # returns 2 > > > You can also compose partially applied functions: > > @curry > def add(x, y): > return x + y > > @curry > def mul(x, y): > return x * y > > comp = add(7) * mul(2) # 'mul(2)' is evaluated first, and it's result > passed to 'add(7)' > comp(4) # returns 15 > >>> > > > Perhaps I'd like in Phobos a "curry" (or another name) template that returns > a callable struct that allows both those operations: the currying with > arbitrary partial application and the "*" operator to perform function > composition (I think the two pieces of functionality go well together despite > being different things, because they are both used in a very functional style > of coding). > > Bye, > bearophile
So, in the next release std.functional.curry has been renamed to std.functional.partial: https://github.com/D-Programming-Language/phobos/pull/1979 I was starting to work on a proper curry replacement, but due to some real-life stuff I haven't had time. There's some starting code at https://issues.dlang.org/show_bug.cgi?id=4391 that I was basing mine off of, but I was running into some issues involving static, and a ton of issues with templated functions. This might be something worth looking into? -- Matt Soucy http://msoucy.me/ -- Matt Soucy http://msoucy.me/
