[Swift-devel] Standard Library Proposal/Discussion Page

[Mihael Hategan]

On Tue, 2015-01-20 at 21:59 -0600, Ketan Maheshwari wrote:
> Neat!
> 
> Comments:
> 
> -- Statistical functions in a standard library seem out of place to me. One
> may ask, why just stop with statistical functions and not also include
> vector and matrix related functions such as cross and dot products or
> fancier stuff like finding eigen values, etc.

They were in Swift/T and I thought they were useful. Dot products can be
done with the zip() function. Cross products can be done with two nested
foreach loops (although I did consider an outer join function). There
are way too many ways to calculate eigenvalues efficiently, and there
are also all kinds of weird algorithms to do so when you need only some
eigenvalues, either the smallest or the largest. So I don't think we
should get into that business.

So I think the bottom line is that if there is something that is likely
helpful for a lot of users and doesn't require a lot of work, then we
should probably have it there.

> 
> -- sqrt and cbrt seem redundant as we already provide pow with float
> exponent.

True. But it looks like most languages provide all of them anyway  (I
can't really think of a language that doesn't have sqrt). I guess it's
just nicer to write sqrt(2) than of pow(2, 0.5).

Mihael

> 
> Regards,
> Ketan
> 
> On Tue, Jan 20, 2015 at 6:56 PM, Mihael Hategan <hategan at mcs.anl.gov> wrote:
> 
> > Hi,
> >
> > I made a wiki page on github where we could discuss the standard
> > library: https://github.com/swift-lang/swift-k/wiki/StandardLibrary
> >
> > It's a draft and there are some rough edges. In particular:
> >
> > - regular expression support: substitutions can be done either directly
> > or with a combination between a function that returns capture groups and
> > a formatting function that replaces certain tokens with elements of an
> > array. One could overload the format() function to, in addition to
> > standard formatting specs, also support something like %s[index]. Or
> > have a separate formatting function that only deals with this specific
> > problem. I'm not sure.
> >
> > - some of the array functions may be difficult to implement as
> > specified, or there may be different functions that solve the problems
> > better. In particular when joining arrays of arrays, there is some
> > freedom in how to order the elements of the resulting array.
> >
> > - read and write: it may not be easy to implement a read that can return
> > any type in T. There is some precedent in other languages that support
> > serialization for this.
> >
> > Anyway, I added red exclamation marks and red question marks where
> > things aren't quite clear.
> >
> > I'm assuming that most of us will agree on most of the things. However,
> > if you have a wildly different proposal, it might be wise to create
> > another page instead of editing this one.
> >
> > Mihael
> >
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> >