[Swift-devel] Swift reference manual and syntax specification

Sun Mar 10 18:07:56 CDT 2013

Sounds good to me.  I've been thinking, for other reasons, about doing a
tech report on Swift/T to serve as a reference for academic purposes, since
we don't have anything we can readily cite.  This would include formal
semantics for Swift/T.

Aside from formal specifications, I think one major gap is concrete
examples that illuminate the trickier points of semantics.  I personally
find well-constructed examples more helpful for most purposes than formal
specifications, but I think that may come down to different learning
styles.   E.g. one example that I think is enlightening is the one below,
which prints 10, 10 times.  Really emphasises the point that Swift is
declarative rather then imperative.

int A[];
foreach i in [1:10] {
  A[i] = i;
  trace(size(A));
}

- Tim

On Sun, Mar 10, 2013 at 4:28 PM, Michael Wilde <wilde at mcs.anl.gov> wrote:

> Hi All,
>
> We have an activity underway within the ExTENCI project to improve Swift's
> tutorial and documentation, in collaboration with Amy Apon (chair of
> Computer Science at Clemson and OSG collaborator) and Clemson graduate
> student Eric Skogen.
>
> I suggested that we use support questions on the swift-* email lists as
> one guide to where documentation needs improvement, citing a recent
> question from a new user who didn't understand what can go in an app()
> function.
>
> Amy recently suggested that we publish a syntax specification for Swift
> (which is a great idea and long overdue) and pointed out that the syntax
> spec could/would have made clear to this new user that you can't put an
> assignment in an app def.
>
> What I believe we need for Swift is a top-notch User Guide that can double
> as a hands-on tutorial, and a separate, concise but complete Reference
> Manual that precisely states language syntax and semantics, and can be used
> by both users (to answer questions not made clear in the User Guide) and
> developers (to discuss subtleties or proposed changes in semantics and to
> deal with implementation issues).
>
> While the User Guide needs to be organized in a reasonable order for
> exposing the language, the Reference Manual needs to be laid out more
> top-down (in terms of compilation units) and bottom-up (in terms of lexical
> issues).
>
> Eric, David, and Ketan are discussing and working on the User Guide. Ive
> asked Ketan to see if the informal BNF-like syntax of the classic K&R C
> book can be readily adapted to Swift, and also suggested that the concise
> compact style of the Swift/T User Guide is in fact more of a reference
> manual already, and could form the basis of a complete reference manual
> that ideally can serve both Swift/K and Swift/T.
>
> We'll need and be having a lot more discussion on both the User Guide and
> Reference Manual, but with this e-mail I wanted to move all such discussion
> to this list (swift-devel).
>
> - Mike
>
> ----- Original Message -----
> > From: "Amy Apon" <aapon at clemson.edu>
> > To: "Michael Wilde" <wilde at mcs.anl.gov>
> > Cc: "Eric Skogen" <eskogen at g.clemson.edu>, "David Kelly" <
> davidk at ci.uchicago.edu>, "Ketan Maheshwari"
> > <ketan at mcs.anl.gov>
> > Sent: Sunday, March 10, 2013 1:05:54 PM
> > Subject: Re: [Swift-user] Variable Declaration
> >
> > Mike,
> >
> >
> > This is a good idea -- looking at support questions to understand
> > where the "pain points" are.
> >
> >
> > This particular question is related to our conversation on the last
> > call. If we could come up with a grammar or grammar-like description
> > of Swift, then explaining the concept below (that an app()
> > function's body is restricted to contain a single command line
> > template and nothing else),would be explained with a tutorial about
> > the grammar. Are we still looking at this?
> >
> >
> > I would like to schedule another call that includes you, me, and
> > Eric, I think, to keep in touch. How does your time look on
> > Wednesday afternoon this week?
> >
> >
> > Amy
> >
> >
> >
> >
> >
> > Amy Apon, Ph.D.
> > Professor and Chair, Division of Computer Science, School of
> > Computing
> > Clemson University
> > 221 McAdams
> > Phone: 864-656-5769
> >
> >
> >
> >
> >
> >
> >
> >
> > On Sun, Mar 10, 2013 at 12:30 PM, Michael Wilde < wilde at mcs.anl.gov >
> > wrote:
> >
> >
> > Eric, All,
> >
> > I think we can gain a lot of insight into documentation/training
> > needs by observing the questions users come with when first using
> > Swift, such as this one.
> >
> > - restrictions on what can be in an app() body, and how you code
> > around them
> >
> > - guidance on the use of types and type names
> >
> > In other words, we can look at support questions and ask "how can the
> > learning roadmap make such support questions less likely to happen".
> >
> > Mike
> >
> > ----- Forwarded Message -----
> > From: "Tim Armstrong" < tim.g.armstrong at gmail.com >
> > To: "Michael Wilde" < wilde at mcs.anl.gov >
> > Sent: Saturday, March 9, 2013 5:56:39 PM
> > Subject: Re: [Swift-user] Variable Declaration
> >
> > What Mike said. I was also going to say that your line:
> >
> > type string;
> >
> > may cause problems: string is a built-in type and you don't need to
> > define it.
> >
> > - Tim
> >
> >
> > On Sat, Mar 9, 2013 at 5:55 PM, Michael Wilde < wilde at mcs.anl.gov >
> > wrote:
> >
> >
> > Jay,
> >
> > An app() function's body is restricted to contain a single command
> > line template and nothing else. So instead of:
> >
> >
> > app (messagefile t) parse(messagefile n) {
> > string v = @regexp("abcdefghi", "c(def)g","monkey");
> > echo @extractint(n) stdout=@filename(t);
> > }
> >
> > ...you need create a separate ("compound") function to do things like
> > string v=(). You can embed arbitrary expressions in the app() body,
> > but it can only have one semicolon-terminated command. Thats the
> > likely cause of the syntax error.
> >
> > Also note that your statement "string v = ..." is creating a value
> > that as far as I can see is not used anywhere, so you may want to
> > re-examine that logic.
> >
> > - Mike
> >
> >
> >
> > ----- Original Message -----
> > > From: "Jay Lee" < jlee734 at gmail.com >
> > > To: swift-user at ci.uchicago.edu
> > > Sent: Saturday, March 9, 2013 5:48:17 PM
> > > Subject: [Swift-user] Variable Declaration
> > >
> > >
> > > Hello,
> > >
> > > I just started with swift today, so excuse my lack of knowledge. I
> > > have the following code:
> > >
> > > type messagefile;
> > > type string;
> > >
> > > app (messagefile t) parse(messagefile n) {
> > > string v = @regexp("abcdefghi", "c(def)g","monkey");
> > > echo @extractint(n) stdout=@filename(t);
> > > }
> > >
> > > app (messagefile t) greeting() {
> > > echo "Hello, world!" stdout=@filename(t);
> > > }
> > >
> > > messagefile outfile <"hello.txt">;
> > > messagefile input <"compile.txt">;
> > >
> > > outfile = parse(input);
> > >
> > >
> > >
> > > I get an error: Could not compile SwiftScript source: line 6:10:
> > > expecting a semicolon, found '='
> > >
> > > I found that there are mappers that can be used to declare
> > > variables
> > > (namely files), but are these required?
> > >
> > >
> > >
> > > _______________________________________________
> > > Swift-user mailing list
> > > Swift-user at ci.uchicago.edu
> > > https://lists.ci.uchicago.edu/cgi-bin/mailman/listinfo/swift-user
> > _______________________________________________
> > Swift-user mailing list
> > Swift-user at ci.uchicago.edu
> > https://lists.ci.uchicago.edu/cgi-bin/mailman/listinfo/swift-user
> >
> >
> >
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