lat? and atom? not in guile?

lat? and atom? not in guile?

[Joshua Branson]

Hello,

This question comes from a non-scheme guy.  I'm not trying to be
critical of guile.  I'm just curious.

So I have the book "The Little Schemer".  The book describes the
procedures: "lat?" and "atom?".  Surprisingly, guile does not seem to
define these procedures by default.  I had assumed that these procedures
were apart of standard scheme, but I guess that is not the case.

Is there any plan to define these procedures?

Thanks,

Joshua

Re: lat? and atom? not in guile?

[Thompson, David]

Hi Joshua,

On Tue, Jun 19, 2018 at 11:18 AM, Joshua Branson <jbranso@fastmail.com> wrote:
>
> So I have the book "The Little Schemer".  The book describes the
> procedures: "lat?" and "atom?".  Surprisingly, guile does not seem to
> define these procedures by default.  I had assumed that these procedures
> were apart of standard scheme, but I guess that is not the case.

Great book! One of my favorites. But yeah, you guessed correctly. They
are not part of any Scheme standard nor are they a part of Guile's own
standard library.  They are unique to The Little Schemer's vocabulary.
In the 4th edition of the book, an implementation of atom? is given
for both Scheme and Common Lisp on page 10, and lat? on page 16, since
the authors knew they couldn't expect the user's Lisp implementation
to have those built-in.

> Is there any plan to define these procedures?

I'm not a maintainer but I wouldn't expect these to be added.

Hope this helps!

- Dave

Re: lat? and atom? not in guile?

[John Cowan]

Neither is part of any Scheme standard.  Most Schemes that define atom?,
define it as (lambda (x) (not (pair? x)), tracking the standard Common Lisp
definition.  But TLS excludes () from atoms as well.  The definition used
by TLS is on p. xiii of the fourth edition:

(define atom?
  (lambda (x)
    (and
      (not (pair? x))
      (not (null? x)))))

As for lat?, it is a non-standard acronym for "list of atoms".  It is
defined on page 16:

(define lat?
  (lambda (l)
    (cond
      ((null? l) #t)
      ((atom? (car l)) (lat? (cdr l)))
      (else #f))))


I have rewritten this from TLS's dialect to use standard #t and #f instead
of t and nil.


On Tue, Jun 19, 2018 at 11:18 AM, Joshua Branson <jbranso@fastmail.com>
wrote:

>
> Hello,
>
> This question comes from a non-scheme guy.  I'm not trying to be
> critical of guile.  I'm just curious.
>
> So I have the book "The Little Schemer".  The book describes the
> procedures: "lat?" and "atom?".  Surprisingly, guile does not seem to
> define these procedures by default.  I had assumed that these procedures
> were apart of standard scheme, but I guess that is not the case.
>
> Is there any plan to define these procedures?
>
> Thanks,
>
> Joshua
>
>

Re: lat? and atom? not in guile?

[Zelphir Kaltstahl]

> ------------------------------
>
> Message: 2
> Date: Tue, 19 Jun 2018 11:18:30 -0400
> From: Joshua Branson <jbranso@fastmail.com>
> To: guile-user@gnu.org
> Subject: lat? and atom? not in guile?
> Message-ID: <877emuyfcp.fsf@fastmail.com>
> Content-Type: text/plain
>
>
> Hello,
>
> This question comes from a non-scheme guy.  I'm not trying to be
> critical of guile.  I'm just curious.
>
> So I have the book "The Little Schemer".  The book describes the
> procedures: "lat?" and "atom?".  Surprisingly, guile does not seem to
> define these procedures by default.  I had assumed that these procedures
> were apart of standard scheme, but I guess that is not the case.
>
> Is there any plan to define these procedures?
>
> Thanks,
>
> Joshua

Good choice, I am reading it too currently. Maybe I should share my unit
tests somewhere?

I think many Schemes do not implement these procedures. Guile does not
and neither does Racket, which I used for most of the books examples and
exercises. I think those procedures are defined in the book in order to
have a common ground for a lot of Schemes, so that you can use whatever
you want and so that the ideas of the book are clear and not dependent
on one specific Scheme dialect.

I don't know about any plans of the Guile developers though.

~ Zelphir

Re: lat? and atom? not in guile?

[Shakthi Kannan]

Hi,

--- On Tue, Jun 19, 2018 at 11:03 PM, Zelphir Kaltstahl
<zelphirkaltstahl@gmail.com> wrote:
> I don't know about any plans of the Guile developers though.

Include it, and the developers can write "The Little Guiler" book.

SK

-- 
Shakthi Kannan
http://www.shakthimaan.com

Re: lat? and atom? not in guile?

[Joshua Branson]

Shakthi Kannan <shakthimaan@gmail.com> writes:

> Hi,
>
> --- On Tue, Jun 19, 2018 at 11:03 PM, Zelphir Kaltstahl
> <zelphirkaltstahl@gmail.com> wrote:
>> I don't know about any plans of the Guile developers though.
>
> Include it, and the developers can write "The Little Guiler" book.

Haha!  That would be perfect!

>
> SK

Re: lat? and atom? not in guile?

[Joshua Branson]

"Thompson, David" <dthompson2@worcester.edu> writes:

> Hi Joshua,
>
> On Tue, Jun 19, 2018 at 11:18 AM, Joshua Branson <jbranso@fastmail.com> wrote:
>>
>> So I have the book "The Little Schemer".  The book describes the
>> procedures: "lat?" and "atom?".  Surprisingly, guile does not seem to
>> define these procedures by default.  I had assumed that these procedures
>> were apart of standard scheme, but I guess that is not the case.
>
> Great book! One of my favorites. But yeah, you guessed correctly. They
> are not part of any Scheme standard nor are they a part of Guile's own
> standard library.  They are unique to The Little Schemer's vocabulary.
> In the 4th edition of the book, an implementation of atom? is given
> for both Scheme and Common Lisp on page 10, and lat? on page 16, since
> the authors knew they couldn't expect the user's Lisp implementation
> to have those built-in.

Oh hey David!  Thanks for the explanation!  Maybe I need to take another
look at that book then.  I found it a little repetitive, but I am
probably not quite grasping some of the fundamentals.  

>
>> Is there any plan to define these procedures?
>
> I'm not a maintainer but I wouldn't expect these to be added.
>
> Hope this helps!
>
> - Dave

Re: lat? and atom? not in guile?

[John Cowan]

On Wed, Jun 20, 2018 at 10:37 AM, Joshua Branson <jbranso@fastmail.com>
wrote:


> Oh hey David!  Thanks for the explanation!  Maybe I need to take another
> look at that book then.  I found it a little repetitive, but I am
> probably not quite grasping some of the fundamentals.
>

It's meant to be repetitive.  It's explicitly compared in the introduction
to Hanon's finger exercises for the piano:  C-E-F-G-A-G-F-E,
D-F-G-A-B-A-G-F, E-G-A-B-C-B-A-D and so on forever, up the scale and down
in every key.  Boring as hell, but just the thing to get fluency into your
fingers.

-- 
John Cowan          http://vrici.lojban.org/~cowan        cowan@ccil.org
As we all know, civil libertarians are not the friskiest group around --
comes from  forever being on the qui vive for the sound of jack-booted
fascism coming down the pike.           --Molly Ivins

Re: lat? and atom? not in guile?

[Thompson, David]

On Wed, Jun 20, 2018 at 10:40 AM, John Cowan <cowan@ccil.org> wrote:
> On Wed, Jun 20, 2018 at 10:37 AM, Joshua Branson <jbranso@fastmail.com>
> wrote:
>
>
>> Oh hey David!  Thanks for the explanation!  Maybe I need to take another
>> look at that book then.  I found it a little repetitive, but I am
>> probably not quite grasping some of the fundamentals.
>>
>
> It's meant to be repetitive.  It's explicitly compared in the introduction
> to Hanon's finger exercises for the piano:  C-E-F-G-A-G-F-E,
> D-F-G-A-B-A-G-F, E-G-A-B-C-B-A-D and so on forever, up the scale and down
> in every key.  Boring as hell, but just the thing to get fluency into your
> fingers.

It's repetitive but honestly I found that the comedic writing made the
exercises very entertaining. I was rarely bored.  I don't play the
piano, but I do play drums, and the equivalent to Hanon's finger
exercises is an old book called Stick Control, which is definitely in
the boring as hell category! I'm glad that Lisp beginners have
something more fun available. :)

- Dave

Re: lat? and atom? not in guile?

[Joshua Branson]

John Cowan <cowan@ccil.org> writes:

> On Wed, Jun 20, 2018 at 10:37 AM, Joshua Branson <jbranso@fastmail.com> wrote:
>  
>  Oh hey David!  Thanks for the explanation!  Maybe I need to take another
>  look at that book then.  I found it a little repetitive, but I am
>  probably not quite grasping some of the fundamentals.  
>
> It's meant to be repetitive.  It's explicitly compared in the introduction to Hanon's finger exercises for the piano:  C-E-F-G-A-G-F-E, D-F-G-A-B-A-G-F, E-G-A-B-C-B-A-D and so on forever, up
> the scale and down in every key.  Boring as hell, but just the thing to get fluency into your fingers.

Re: lat? and atom? not in guile?

[Joshua Branson]

"Thompson, David" <dthompson2@worcester.edu> writes:

> On Wed, Jun 20, 2018 at 10:40 AM, John Cowan <cowan@ccil.org> wrote:
>> On Wed, Jun 20, 2018 at 10:37 AM, Joshua Branson <jbranso@fastmail.com>
>> wrote:
>>
>>
>>> Oh hey David!  Thanks for the explanation!  Maybe I need to take another
>>> look at that book then.  I found it a little repetitive, but I am
>>> probably not quite grasping some of the fundamentals.
>>>
>>
>> It's meant to be repetitive.  It's explicitly compared in the introduction
>> to Hanon's finger exercises for the piano:  C-E-F-G-A-G-F-E,
>> D-F-G-A-B-A-G-F, E-G-A-B-C-B-A-D and so on forever, up the scale and down
>> in every key.  Boring as hell, but just the thing to get fluency into your
>> fingers.
>
> It's repetitive but honestly I found that the comedic writing made the
> exercises very entertaining. I was rarely bored.  I don't play the
> piano, but I do play drums, and the equivalent to Hanon's finger
> exercises is an old book called Stick Control, which is definitely in
> the boring as hell category! I'm glad that Lisp beginners have
> something more fun available. :)

hahaha.  Well thanks for the fresh perspective.

>
> - Dave