String Tapas Redux: Beyond mere string interpolation

[Tagir Valeev]

It's interesting that in both Scala and JavaScript when you define
custom interpolation policy, you get a collection of Strings instead
of a single string. So in the article, we see "error: file \{} not
found" but in Scala/JS you would get List.of("error: file ", " not
found")). While for localization, having a single string already baked
might be beneficial, I think in the general case, having separate
parts may be helpful for interpolation implementations, as no
additional parsing (search for \{}) would be necessary. Also, the
placeholder designation with \{} (or whatever else) is quite
arbitrary. If we just provide a list, we would not need to make this
choice. And probably the interop between JVM languages would be easier
(of course, Scala/Kotlin folks would like to use template policies
defined in Java, and vice versa).

Another alternative is to have a single list of template fragments,
something like this:

sealed interface TemplateFragment {
  interface StringFragment extends TemplateFragment {
    String content();
  }
  interface ExpressionFragment extends TemplateFragment {
    Object content();
  }
}

Now, TemplatedString is just a List of TemplateFragments (it's not
always necessary that ExpressionFragments should be interleaved with
StringFragments, you may have two ExpressionFragments next to each
other).


On Fri, Sep 17, 2021 at 5:38 PM Tagir Valeev <amaembo at gmail.com> wrote:
>
> As for custom template processing in JavaScript, see "Tagged
> templates" section here:
> https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Template_literals
>
> On Fri, Sep 17, 2021 at 2:15 PM Tagir Valeev <amaembo at gmail.com> wrote:
> >
> > Btw people say that Scala provides a similar mechanism using
> > StringContext class:
> > https://www.scala-lang.org/api/2.12.2/scala/StringContext.html
> > In fact, Scala's `s` prefix before interpolated literal is a recipe
> > for interpolation provided by a standard library, not by language. And
> > it's possible to declare your own recipes. Quite similar to our
> > proposal.
> >
> > Also, there's some frustration in Twitter comments regarding the
> > article narrative like "We will do it better than existing languages"
> > (especially because Scala was chosen as an example). Probably, the
> > wording could be better, with more respect to other languages. Of
> > course, this doesn't undermine the suggested feature itself, the
> > feature is great.
> >
> > With best regards,
> > Tagir Valeev.
> >
> > On Fri, Sep 17, 2021 at 9:35 AM Tagir Valeev <amaembo at gmail.com> wrote:
> > >
> > > Hello!
> > >
> > > Just read the proposal. I don't have any useful comments for now. For
> > > me, the proposal looks great as is. Go ahead and implement it :D
> > >
> > > With best regards,
> > > Tagir Valeev.
> > >
> > > On Thu, Sep 16, 2021 at 8:28 PM Jim Laskey <james.laskey at oracle.com> wrote:
> > > >
> > > > Amber experts,
> > > >
> > > > Now that JDK 17 has been plated and left the kitchen, we should have a look-see at one of the new menu items Brian and I have had on a slow boil for these last few months; Templated Strings.
> > > >
> > > > Before you start shouting out, "Templated Strings? This isn't what I ordered! The subject said string interpolation!!!", take the time to follow this link https://github.com/openjdk/amber-docs/tree/master/site/design-notes/templated-strings.md. After reading, we hope you'll see that the offering is much better than interpolation meat and potatoes.
> > > >
> > > > Cheers,
> > > >
> > > > -- Jim