By the way, these are not "partial functions", and shouldn't be called that. These are "partial function applications".
On Saturday, August 4, 2018 at 12:03:50 PM UTC-4, Fabrizio Messina wrote: > > > Hello, I would like to propose a new method to create a partial function. > > At the moment we have to load the *partial* function from the *functool* > library, and apply it to an existing function, e.g. > > from functools import partial > > > def add(x: int, y: int) -> int: > return x + y > > > add_2 = partial(add, 2) > > > > While partial expose the mechanism excellently its instantiation method > is, at times, not very friendly, I would like to propose a syntactic sugar > to create partial functions, in the case you create a partial function > using *curly braces*: > > > def add(x: int, y: int) -> int: > return x + y > > add_2 = add{2} > > > At the moment this causes SyntaxError so the change is retro-compatible. > > In the case of key word arguments we could have: > > sort_by_x = sort{key=lambda element: element.x} > > > That could be good as it would be an easy way to pre-load functions > without having to eagerly compute it, but without needing to pass the > entire function parameters to to other scopes. > > > # prepare the function > get_sorted_users: Callable[[], Iterator[User]] = sort{users, key=lambda > user: user.creation_date} > > # continue with job at hand > ... > > # some where else, maybe another process > sorted_users = list(get_sorted_users()) > > > > Even create a factory method on the fly: > @dataclass > class Product: > name: str > category: Category > price: Decimal > > > smartphone_factory = Product{category=smartphone_category} > > > > Now all this can already be done with partial, but adding this syntactic > sugar would reduce the perception of `partial` as an advanced feature, > alleviating the use of closures created only for the sake of avoiding an > explicit partial. > > In my opinion this syntactic sugar has a lot of potential adoption seen > the general interest in functional programming. >
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