Re: guile-user Digest, Vol 171, Issue 14

[Cecil McGregor]

As a relative noobie to Guile I have some grievances
with Guile. I started to use it for awhile, get frustrated
and go away, and then, eventually, come back.

My first problem lies in the lack of a decent debugger.
(I can hear the screams of more enlightened Guilers
already!) The stack traces seldom provide filenames
and line numbers to hint where a problem might hide.
While I've read advice to allow the appearance of
filenames/line numbers, I still can't seem to
consistently find these in a stack trace.

I would really like the filename/line number to appear
in a stack trace with the actual source code and not
some partially opaque macro expansion.

Then there is the matter of a good code coverage
tool. Having experienced the benefits of TDD, Test
Driven Development, I insist on good coverage
when I develop in NodeJS and python. I really
need to know that all my code has been tested.

Imagine the obstacle a noobie faces as they
begin learning Guile and they have problems with
debugging and they can't be sure that all their
code has been tested. Yes, they can insert
print statements everywhere, but at what cost?
When they revisit code at a later date, do they
re-insert print statements to demonstrate the
effectiveness of code?

I remember once getting irritated with Guile
because some system code was displaying
a long stack trace for some reason. I spent
about half a day mucking about before
deciding my time was more valuable elsewhere.

Has anyone followed up on the SICP classes
and asked why scheme was not more popular?
Was it so unpopular that the students took up
C/C++/Java instead? SICP uses a "portable"
form of Scheme that apparently works with
almost any Scheme implementation. SICP
doesn't deal with messy system issues or
implementing larger projects. Small programs
such as SICP offers does not require serious
debugging. As programs become systems
the necessity of serious debugging rears
an ugly side.

Debugging and TDD become critical when/if
Guile gets used with larger groups. A decent
debugger provides an ideal environment to
assist in understanding code. Step through
with various cases and your understanding
increases. Use TDD and examine the coverage.

Ease of use with a decent debugger significantly
reduces friction in learning and using a language.

(Yes, there are holes and exceptions in the above.
Flames to /dev/null.)





On Tue, Feb 14, 2017 at 5:11 AM, <address@hidden> wrote:

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> Today's Topics:
>
>    1. Re: How to make GNU Guile more successful (Marko Rauhamaa)
>    2. Re: How to make GNU Guile more successful (Panicz Maciej Godek)
>    3. Help formatting a UTC Timestamp (Guy Baumann)
>    4. Re: Help formatting a UTC Timestamp (address@hidden)
>    5. Re: Help formatting a UTC Timestamp (Chris Vine)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 14 Feb 2017 07:59:07 +0200
> From: Marko Rauhamaa <address@hidden>
> To: Arne Babenhauserheide <address@hidden>
> Cc: Panicz Maciej Godek <address@hidden>,
>         "address@hidden" <address@hidden>
> Subject: Re: How to make GNU Guile more successful
> Message-ID: <address@hidden>
> Content-Type: text/plain; charset=utf-8
>
> Arne Babenhauserheide <address@hidden>:
>
> > Marko Rauhamaa <address@hidden> writes:
> >> Then, there's GOOPS, which in my opinion is simply an unnatural way
> >> to go about object-oriented programming. It does violence both to
> >> ordinary OO way of thinking and classic Lisp idioms.
> >
> > GOOPS works pretty well for me where I use it (for dispatch by type).
> > Could you clarify your criticism: Do you think it is bad or is it just
> > different?
>
> GOOPS starts by defining slots. Slots are an objects internal business
> and should not be visible to the outside. Instead, objects should be
> black boxes that interact with methods. For example, the port interface
> is a nice, classic OO API. You don't know anything about the slots of a
> port.
>
> Furthermore, I think an extensive type system is un-Lisp-like. OO is not
> about things belonging to a type but objects interacting through
> methods. In fact, the concept of a "class" could be done away with.
>
> >> Continuations and multiple values are obstacles instead of enablers.
> >
> > I think multiple values are nice. But they are not well-integrated (I
> > have to import something to use them). Why do you think them enablers?
>
> Yes, the multiple values API is a problem in and of itself, but more
> generally, what does:
>
>     (values a b c)
>
> give you on top of, say:
>
>     (list a b c)
>
> > Why do you think that continuations are an obstacle (do you mean
> > general continuations or do you mean prompts)?
>
> Continuations prevent you from implementing Python's try/finally and
> emacs' (unwind-protect).
>
> On the other hand, I don't think any application developer would come to
> a point of thinking, "Hey, I know, I'll use a continuation!"
>
> >> asyncio, type annotation,
> >
> > type annotations should provide nice ways to optimize for pypy and
> > other more optimizing Python implementations.
>
> You can't have it bothways. A dynamic language liberates you from
> shackles and boilerplate even if it destroys your performance. The
> moment you bring in the boilerplate, you are back to Java.
>
> > Decorators are really cool to use:
>
> Have yet to find a need for one.
>
> >> dunder jungle,
> >
> > What?s that?
>
> <URL: https://docs.python.org/3/genindex-_.html>
>
> >> meta-object programming,
> >
> > That?s needed to make some things elegant. "Different 20%"-rule again.
>
> Again, I haven't yet found a need to deviate from the regular object
> semantics.
>
> >> Unicode illusion. (Guile has fallen into that last trap as well,
> >> unfortunately.)
> >
> > I?m using Python and Guile for physics and math (to some degree), and
> > having good Unicode-support is great for that. What?s your practical
> > criticism here?
>
> In Linux, all pathnames, files, sockets, environment variables and
> command-line arguments are, or deal with, bytes. The bytes are often
> encoded with UTF-8, but a programming language cannot assume that, even
> if LOCALE promises otherwise.
>
> It would be better to leave Unicode out of Guile's system interface and
> have the application encode and decode explicitly where needed.
>
> >> There's one thing Python has over Guile, still: Python's system call
> >> support is outstanding. For example, I managed to implement a
> >> full-blown shell using Python. That was the first time I ever ran
> >> into terminal-related system calls, and Python had them all.
> >
> > Which ones are missing in Guile?
>
> For example tcgetattr(3). (Ok, not a system call.)
>
> Missing epoll(2) is inconvenient. Not being able to transfer an open
> file descriptor via sendmsg(2) is really bad.
>
>
> Marko
>
>
>
>
>
> ------------------------------
>
> Message: 2
> Date: Tue, 14 Feb 2017 10:54:38 +0100
> From: Panicz Maciej Godek <address@hidden>
> To: Arne Babenhauserheide <address@hidden>
> Cc: Amirouche <address@hidden>,        "address@hidden"
>         <address@hidden>
> Subject: Re: How to make GNU Guile more successful
> Message-ID:
>         <address@hidden
> gmail.com>
> Content-Type: text/plain; charset=UTF-8
>
> 2017-02-13 23:54 GMT+01:00 Arne Babenhauserheide <address@hidden>:
>
> >
> > Panicz Maciej Godek <address@hidden> writes:
> >
> > > 2017-02-13 12:06 GMT+01:00 Arne Babenhauserheide <address@hidden>:
> > > There's also this problem with Scheme that it is a very diverse
> > > community with plethora of implementations. And while I use Guile, I
> > > don't mind using Chicken or Chez or Gambit for various purposes. Or
> > > even Stalin sometimes. Maybe, instead of getting a better compiler, we
> > > should focus on integrating existing compilers?
> >
> > You?ll have to ask Andy Wingo about all the hidden complexity in just
> > wiring in a compilier. I assume it?s pretty big.
> >
> > I think the r7rs folks are working in that regard, to make it possible
> > to write code which you can simply run through another Scheme
> > implementation if you need those strengths.
> >
> > I started to use (import (...)) to get closer to that: Getting used to
> > the portable stuff (also it?s shorter than (use-modules (...)). But not
> > everything is portable, and performance critical stuff most definitely
> > isn?t.
> >
> > And for the stuff I do, most things get performance critical at some
> > point. Even looking for null-bytes in a file becomes a bottleneck if you
> > have a few hundred TiB to check.
> >
> > Though I mainly need to write Python at work (Scheme isn?t widespread
> > enough for the folks there ? Python is everywhere in science
> > nowadays). It?s still efficient to do that and I enjoy it, but not as
> > much as writing Scheme.
> >
> > >> And it's easy to packages.
> > >> >
> > >> >   => Another pain topic. In reality it's very easy to package
> > >> >      all sort of guile programs for guix. But guix itself needs
> > >> >      to be more stable.
> > >>
> > >> I wish I had guildhall ready. Got hit by
> > >> time-eaten-by-other-project-because-guildhall-was-priority-three.
> > >>
> > >> It needs to be easy to not just package some code, but also to share
> > >> that package without hitting a bottleneck.
> > >>
> > > What happened to initiatives like Scheme NOW, that tried to integrate
> > > various groups of developers.
> >
> > I did not hear from that.
> >
> > > Or why can't we just "steal" eggs from Chicken? (I mean it. They
> already
> > > have that problem solved)
> >
> > Do you mean, integrating eggs into Guile so we could just use them?
> > Conceptually what would be needed for that is a metadata field: "Works
> > with Guile". And practically someone to write the integration.
> >
> >
> There's surely many ways to approach that issue. The point is that for some
> reason, Schemers from various tribes prefer to reinvent the wheel,
> rather than use an existing one. (Not that I am any different)
> However, I also think that these CPAN-alike solutions are far from optimal:
> ideally, programming could be made an experience similar the game
> "The Journey" by thatgamecompany (where you travel to your goal and
> sometimes
> encounter other players heading the same direction), and the repository
> itself could look
> more like Wikipedia (but first we'd need to start perceiveing programming
> as
> a compact way of representing knowledge)
>
> > Practically put: We need Andy Wingo to nitpick the tutorial about things
> > >> which will cause overheads the compiler cannot fix easily ? including
> > >> expensive use of macros.
> >
> > > I definitely oppose. If Chez has something solved better, why not use
> > > Chez?
> >
> > It?s not "why not use Chez", but rather "what should I teach new
> > people?"
> >
> > They are already learning a new language. When I now go and point them
> > towards many different implementations which differ in details of stuff
> > I teach them, I?m throwing more complexity at them. More things to
> > understand before even starting to write working code.
> >
> > I totally agree. Programmers shouldn't be concerned whether they're
> using Chez or Guile or Gambit or Stalin or whatever else. Ideally, they
> should do well without even knowing that such things exist.
> There are Schemes, such as Kawa or Biwa or IronScheme, that are tied
> to their environment, but most of them just run on the PC
>
>
> > Maybe it would already help to mark the code which will work the same in
> > all (r7rs) Schemes. Is there stuff which is well optimized in all
> > Schemes? Who knows that? The r7rs benchmarks look like this is very much
> > not the case: http://ecraven.github.io/r7rs-benchmarks/benchmark.html
> >
> > (Or rather, the benchmarks would ask: "why should I *not* use Chez or
> > stalin for everything I do?" Because those are the fastest for most
> > tasks.)
> >
> > But that might mean to write less elegant or efficient code to keep it
> > cross-implementation. Should I rather teach new people to solve a
> > problem as well as possible, or teach them to solve a problem in a
> > portable way?
> >
> >
> I think that in principle, the programmer should only focus on writing
> most elegant code
>
>
> > In my case, I decided to use Guile by checking Scheme
> > implementations. There were three with roughly equal activity and
> > features. I chose Guile, because it?s a GNU project and it has a long
> > history of surviving changing maintainers, so my skills are most likely
> > to stay useful.
> >
> >
> That's interesting. I chose it by trying to add a scripting language to my
> game engine written in C++. But I guess that if I was starting now, I'd
> write
> the whole engine in Chez (which wasn't opensource until last year)
>
>
> > > The ultimate goal is not to optimize programs, but programmers.
> >
> > I?m not sure that I want to optimize them, I want to teach them tools to
> > be more efficient and enjoy their work more (and teach myself the same).
> >
> >
> Yeah, maybe I used a harsh word, but I meant exactly optimizing
> programmers' efficiency (or if it sounds too bad, "giving them tools
> to be more efficient")
>
>
> > I think one important point for Scheme would be to gather some consensus
> > points. The Zen of Python is part of what made that one community
> > strong. There is no reason why there should not be a Zen of Scheme,
> > along with implementation-specific Koans which extend it.
> >
> > Do you have ideas for principles which could be shared by most Schemers?
> >
> >
> It depends on the most Schemers, not me :)
> However, you can have a look at the (grand scheme) glossary that I've been
> maintaining for some time:
>
> https://github.com/plande/grand-scheme
>
> of course, the intent is to make the glossary usable for someone else than
> me,
> and I can boast that I have at least one user distinct from the maintainer.
> You can have a look and let me know what you think. (for now it only works
> with Guile). In particular, are there any factors that could convince you
> to
> adapt it as a base for your library, or what would you want changed
> (I assume you won't stop at the README file).
> Anyways, the rules (of thumb) are:
>
>
>    - functions should be pure
>    - language constructs that cause side-effects should be encapsulated
>    with macros that limit the extent of those side-effects
>    - if possible, use the quasiquote macro, rather than cons, append or
> list
>    - prefer the use of match <http://synthcode.com/scheme/match.scm> to
> cond,
>    if the patterns are simple
>    - never use abbreviations
>    - use commented prepositions to separate arguments
>
> Also, I recently added infix syntax to Scheme, but (unlike in Racket or
> David Wheeler's solutions) in the way it is still a prefix syntax. So for
> example,
> instead of writing (< a b), one ought to write (is a < b). The rationale is
> that
> prefix notation is terrible for non-symmetrical binary predicates, because
> it
> obscures the roles of respective arguments (in addition, (is a < b <= c)
> expands
> to (and (< a b) (<= b c))). I'm still not sure whether it is a good idea,
> but I have
> no reasons to think that it is bad either :]
> [Curiously enough, I think that prefix notation in arithmetic is just fine:
> (+ a b c) reads as "sum of a, b and c"]
>
> > Also, I think that the astounding success of R provides hints with
> > > regard what is needed for a programming language to gain popularity. R
> > > has a large repository of packages that fills a certain niche. When I
> > > advertised my Pamphlet on Hacker News, someone responded critically:
> > > "are there out of the box libraries to estimate a zero inflated
> > > negative binomial regression model in guile". Of course, if I knew
> > > what a zero-inflated negative binomial regression model, I could
> > > deliver an implementation by just explaining the notions used in that
> > > phrase.
> >
> > I think there?s a quote which applies here: "Most people only use 20% of
> > the capabilities of any program, but they do not use the same 20%."
> > ? Joel Spolksy, if I remember correctly.
> >
> > And to make people really dig into it, a programming language must work
> > well for all tasks they might encounter. That?s why a comprehensive
> > standard library is important: It gives the assurance that the skills
> > you learn will stay useful wherever you go.
> >
> > There?s a nice quote from Rust folks: "people started to feel safe when
> > we told them about unsafe" ? someone on GNU social.
> > This essentially says: they then saw that Rust could work in the
> > uncomfortable way some of their tasks might require. That they could
> > take it into harsher territory, if needed.
> >
> > I like it that you and Amirouche look a lot at the sociocultural
> perspective
> of programming
>
>
> > > (But then again, I try to write functional programs whenever
> > > possible, often consciously sacrificing time complexity of my
> > > solutions, and I'm aware that not everybody will like it.)
> >
> > I look for ease of understanding, with functional programming techniques
> > being a useful tool to reduce complexity and to simplify refactoring.
> >
> > But then, this is a point where we actually move into a similar
> > direction out of different motives. I think the only problem here is the
> > danger of assuming contradiction where there does not need to be
> > any. Just different nuances of Zen :)
> >
> > Yes, to me the ease of understanding is also crucial. (I'd even go
> further and say that undestranding is the very point of programming)
>
> Best regards,
> Panicz
>
>
> ------------------------------
>
> Message: 3
> Date: Tue, 14 Feb 2017 12:27:16 +0000
> From: Guy Baumann <address@hidden>
> To: address@hidden
> Subject: Help formatting a UTC Timestamp
> Message-ID: <address@hidden>
> Content-Type: text/plain; charset=us-ascii
>
> I am trying to format a timestamp from an api. It is sent in the
>  format "2011-03-24T20:30:47Z"
>
> what I want to output is something like this
> (strftime "%d %b %g " (localtime (current-time)) )
>
> However I am unable to work out how to do this, have tried using
>  string->date with results below
>
> Enter `,help' for help.
> scheme@(guile-user)> (define date "2011-03-24T20:30:47Z")
> scheme@(guile-user)> (use-modules (srfi srfi-19))
> scheme@(guile-user)> (string->date "~Y-m-dT~H:~M:SZ" date)
> srfi/srfi-19.scm:1415:18: In procedure priv:string->date:
> srfi/srfi-19.scm:1415:18: In procedure string->date: TIME-ERROR type
> bad-date-format-string: "2011-03-24T20:30:47Z"
>
> Entering a new prompt. Type `,bt' for a backtrace or `,q' to continue.
> scheme@(guile-user) [1]> (string->date date "~Y-m-dT~H:~M:SZ")
> srfi/srfi-19.scm:1415:18: In procedure priv:string->date:
> srfi/srfi-19.scm:1415:18: In procedure string->date: TIME-ERROR type
> bad-date-format-string: "~Y-m-dT~H:~M:SZ"
>
> Entering a new prompt. Type `,bt' for a backtrace or `,q' to continue.
> scheme@(guile-user) [2]> (string->date date "~Y-m-dT~H:~M:SZ")
> srfi/srfi-19.scm:1415:18: In procedure priv:string->date:
> srfi/srfi-19.scm:1415:18: In procedure string->date: TIME-ERROR type
> bad-date-format-string: "~Y-m-dT~H:~M:SZ"
>
> Entering a new prompt. Type `,bt' for a backtrace or `,q' to continue.
> scheme@(guile-user) [3]> (string->date "2000" "~Y")
> srfi/srfi-19.scm:571:22: In procedure encode-julian-day-number:
> srfi/srfi-19.scm:571:22: In procedure -: Wrong type: #f
>
> thanks for any help
>
> //guy
>
>
>
> ------------------------------
>
> Message: 4
> Date: Tue, 14 Feb 2017 13:48:51 +0100
> From: <address@hidden>
> To: address@hidden
> Subject: Re: Help formatting a UTC Timestamp
> Message-ID: <address@hidden>
> Content-Type: text/plain; charset=utf-8; x-action=pgp-signed
>
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> On Tue, Feb 14, 2017 at 12:27:16PM +0000, Guy Baumann wrote:
> > I am trying to format a timestamp from an api. It is sent in the
> >  format "2011-03-24T20:30:47Z"
> >
> > what I want to output is something like this
> > (strftime "%d %b %g " (localtime (current-time)) )
> >
> > However I am unable to work out how to do this, have tried using
> >  string->date with results below
> >
> > Enter `,help' for help.
> > scheme@(guile-user)> (define date "2011-03-24T20:30:47Z")
> > scheme@(guile-user)> (use-modules (srfi srfi-19))
> > scheme@(guile-user)> (string->date "~Y-m-dT~H:~M:SZ" date)
> > srfi/srfi-19.scm:1415:18: In procedure priv:string->date:
> > srfi/srfi-19.scm:1415:18: In procedure string->date: TIME-ERROR type
> bad-date-format-string: "2011-03-24T20:30:47Z"
>
> You got the args reversed: it's first the date string, then the
> template. Besides, you forgot a couple of tildes in your template
> (e.g. it's "~m" and not just "m" and so on). Lastly, the template
> for the zone offset is "~z" (a small z). The "big Z" in your input
> string is just a concrete zone (afaik UTC).
>
> This works:
>
>   scheme@(guile-user)> (define mydate "2011-03-24T20:30:47Z")
>   scheme@(guile-user)> (string->date mydate "~Y-~m-~dT~H:~M:~S~z")
>   $3 = #<date nanosecond: 0 second: 47 minute: 30 hour: 20 day: 24 month:
> 3 year: 2011 zone-offset: 0>
>
> hth
> - -- t
> -----BEGIN PGP SIGNATURE-----
> Version: GnuPG v1.4.12 (GNU/Linux)
>
> iEYEARECAAYFAlii/LMACgkQBcgs9XrR2kbySACfY3yqQgFw4XWIBZo1Nif8exJ1
> jwUAn04XBldYBIWDDhheEjI1nLbFbjhm
> =MJ3B
> -----END PGP SIGNATURE-----
>
>
>
> ------------------------------
>
> Message: 5
> Date: Tue, 14 Feb 2017 13:11:07 +0000
> From: Chris Vine <address@hidden>
> To: Guy Baumann <address@hidden>
> Cc: address@hidden
> Subject: Re: Help formatting a UTC Timestamp
> Message-ID: <address@hidden>
> Content-Type: text/plain; charset=US-ASCII
>
> On Tue, 14 Feb 2017 12:27:16 +0000
> Guy Baumann <address@hidden> wrote:
> > I am trying to format a timestamp from an api. It is sent in the
> >  format "2011-03-24T20:30:47Z"
> >
> > what I want to output is something like this
> > (strftime "%d %b %g " (localtime (current-time)) )
> >
> > However I am unable to work out how to do this, have tried using
> >  string->date with results below
> >
> > Enter `,help' for help.
> > scheme@(guile-user)> (define date "2011-03-24T20:30:47Z")
> > scheme@(guile-user)> (use-modules (srfi srfi-19))
> > scheme@(guile-user)> (string->date "~Y-m-dT~H:~M:SZ" date)
> > srfi/srfi-19.scm:1415:18: In procedure priv:string->date:
> > srfi/srfi-19.scm:1415:18: In procedure string->date: TIME-ERROR type
> > bad-date-format-string: "2011-03-24T20:30:47Z"
> >
> > Entering a new prompt. Type `,bt' for a backtrace or `,q' to continue.
> > scheme@(guile-user) [1]> (string->date date "~Y-m-dT~H:~M:SZ")
> > srfi/srfi-19.scm:1415:18: In procedure priv:string->date:
> > srfi/srfi-19.scm:1415:18: In procedure string->date: TIME-ERROR type
> > bad-date-format-string: "~Y-m-dT~H:~M:SZ"
> >
> > Entering a new prompt. Type `,bt' for a backtrace or `,q' to continue.
> > scheme@(guile-user) [2]> (string->date date "~Y-m-dT~H:~M:SZ")
> > srfi/srfi-19.scm:1415:18: In procedure priv:string->date:
> > srfi/srfi-19.scm:1415:18: In procedure string->date: TIME-ERROR type
> > bad-date-format-string: "~Y-m-dT~H:~M:SZ"
> >
> > Entering a new prompt. Type `,bt' for a backtrace or `,q' to continue.
> > scheme@(guile-user) [3]> (string->date "2000" "~Y")
> > srfi/srfi-19.scm:571:22: In procedure encode-julian-day-number:
> > srfi/srfi-19.scm:571:22: In procedure -: Wrong type: #f
>
> You haven't got the escapes quite right.  This will work:
>
>   (string->date date "~Y-~m-~dT~H:~M:~SZ")
>
> As will this with skipping, given that your example uses numeric values:
>
>   (string->date date "~Y~m~dT~H~M~SZ")
>
> Chris
>
>
>
> ------------------------------
>
> Subject: Digest Footer
>
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> ------------------------------
>
> End of guile-user Digest, Vol 171, Issue 14
> *******************************************
>