It could certainly be implemented now, if it was restrictive to builtin
monad types - like `Option`. The real question would be what sort of syntax
fits in with Rust. Would there be a new bind operator, or have `bind`
instead of `let` in `do` blocks or just reuse let and have any option types
be automatically deconstructed in the binding (yuck).
For example using the first,
fn str_larger_than_five(str: ~str) {
> do {
> val <- from_str("1");
>
> return val > 5;
> }
> }
or perhaps a bind keyword would nicer (my preference, but requires an extra
keyword):
bind val = from_str("1");
return val > 5;
Of course the current usage of `do` would need to be removed in favour of
another keyword.
On Thu, Dec 12, 2013 at 10:55 AM, Brendan Zabarauskas
<[email protected]>wrote:
> Could `do` be implemented using sugar for now? Like, it expects such and
> such methods in order for it to work. We could put it behind a feature flag
> until we have HKT.
>
> ~Brendan
>
> On 12 Dec 2013, at 9:57 am, Zack Corr <[email protected]> wrote:
>
> > Yes, but Rust doesn't have HKT. I was suggesting it on this basis. I'd
> prefer `do` as well.
> >
> >
> > On Wed, Dec 11, 2013 at 5:25 PM, Ziad Hatahet <[email protected]> wrote:
> > On Tue, Dec 10, 2013 at 9:04 PM, Zack Corr <[email protected]> wrote:
> > I think the Monadic null operator (a.k.a. safe property access operator)
> would be pretty useful syntax sugar for mapping over option types, and
> certainly help with the whole "option vs fail" for error checking because
> it essentially allows monad-like functionality without actually having
> (first-class) monads.
> >
> >
> > I still think that having something like Haskell's `do`, or Scala's
> `for` is a better way to go about this. Especially that it generalizes over
> more than just `Option<T>`.
> >
> > --
> > Ziad
> >
> >
> > _______________________________________________
> > Rust-dev mailing list
> > [email protected]
> > https://mail.mozilla.org/listinfo/rust-dev
>
>
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