[swift-evolution] Changing the curried static methods

[Brandon Williams]

Sorry for the confusion, I’m not looking for help to model something in
particular. These are examples to show the difference between the current
curried static convention and the one I think is more expressive.

To iterate, right now CGRect.insetBy(rect)(insets) just reads incorrectly
to me. Considering that Swift aims to be expressive through method names
and argument labels, I would expect this to be CGRect.insetBy(insets)(rect).


On Sun, Mar 13, 2016 at 10:54 PM Erica Sadun <erica at ericasadun.com> wrote:

> > If static methods had their arguments flipped, we'd be able to easily
> construct functions like `CGRect.insetBy(10.0, 10.0)` and
> `CGRect.offsetBy(-20.0, 10.0)`. These are now free functions without any
> mention to a specific rectangle. We could compose them to get a function
> that simulataneously insets and translates, all without mentioning a
> rectangle. With today's static methods we'd have to apply `flip` to each
> one, i.e. `flip(CGRect.insetBy)(10.0, 10.0)`.
> >
> > This becomes very powerful with constructing data pipelines that
> describe how to transform data without ever actually mentioning the data.
> There are quite a few examples of things like this in Cocoa. A nice one is
> Core Image, in which you can build a pipeline of filters that you can feed
> images into.
> >
>
> By your description, it sort of sounds like you could want to create a
> method cascade:
>
> myRect
>    ..insetBy(args)
>    ..offsetBy(args)
>
> In this, the instance passes through each of the function calls, joining
> them into a fluent declaration
> with an implicit receiver.
>
> But it also sounds like you want to use functional chaining. Core Image
> can chain because it always has
> inputImage and outputImage and set defaults:
>
> myRect = myRect.insetBy(args).offsetBy(args)
>
> Alternative, you could be doing some kind of weird chaining thing where so
> long as the output and inputs match
> up they can be composed together:
>
> f = (x: insetByAble).insetBy(args)->(T:offsetByAble).offsetBy(args)->U
> myRect = f(myRect)
>
> But in the end, it kind of almost really sounds like you just want to
> write a function
>
> f(x: CGRect) -> CGRect {
>    x.insetBy(10.0, 10.0)
>    x.offsetBy(-20.0, 10.0)
>    return x
> }
>
> Which of these are you aiming for?
>
> -- E
>
>
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