Quasiquote and Comma symbols

Hello,

Sometimes I have lists that would be easier to build using the actual symbols (like quote) rather than the quote (‘), backquote (`) and comma (,) characters.  I’m wondering what the names are for the quasi quote and comma symbols expanded by the parser in Lispworks.  A search of the documentation has lead to nothing. 

Burton

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Re: Quasiquote and Comma symbols

Hi!

As other people said here, those details are not standardized, and are
not documented. There are libraries for implementation of quasiquoting
which (I think) can be made portable. Original implementaiton of
quasiquote is in CLTL2
(http://www.cs.cmu.edu/Groups/AI/html/cltl/clm/node367.html#SECTION003600000000000000000
)

You can use the original library and/or deduce which structures which
represent quasiquoted data from the source. If you don't want to go
this way, you can try further deducing details from the
implementation.

I made the following experiment in SBCL:

507 CL-USER>(setf *print-pretty* nil)
NIL
508 CL-USER>'``(foo ,(bar ,baz))
(SB-INT:QUASIQUOTE (SB-INT:QUASIQUOTE (FOO #S(SB-IMPL::COMMA :EXPR
(BAR #S(SB-IMPL::COMMA :EXPR BAZ :KIND 0)) :KIND 0))))

So, you might need nested quasiquote to learn something essential. We
see there are some structures which represent quasiquotes. In an
open-source implementation
you can go to the source of the reader (start from the read function
and the result of (get-macro-character #\`) in your open-source
implementation).

I currently have no Lispworks at hand, but you can try similar
experiments until you can deduce what the exact structure is. You have
no source codes, but you can use the result of printer output. If
Lispworks does not show you the unleashed internal structure, try
using inspector on the data Lispworks creates for you.

2017-08-03 6:36 GMT+03:00, BusFactor1 Inc. <busfactor1@gmail.com>:
> Hello,
>
> Sometimes I have lists that would be easier to build using the actual
> symbols (like quote) rather than the quote (‘), backquote (`) and comma (,)
> characters.  I’m wondering what the names are for the quasi quote and comma
> symbols expanded by the parser in Lispworks.  A search of the documentation
> has lead to nothing.
>
> Burton
>

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Re: Quasiquote and Comma symbols

Hi Burton,

CL-USER> (quote `(1 2 ,*x*))

(SYSTEM::BQ-LIST 1 2 *X*)

CL-USER> (quote `(1 2 *x*))

(QUOTE (1 2 *X*))

The details of backquoting, in particular when nested, I have found to
differ quite a lot between LW and SBCL, though I don't recall the
precise details I think SBCL worked the way I thought it should.
Perhaps this is not well specified in the standard.

There are a bunch of related functions, though I couldn't tell you
exactly how they differ, and of course being undocumented I wouldn't
expect LW to notify me if they changed between releases.

CL-USER> (apropos "BQ-")
LW-XP::COPY-BQ-STRUCT (defined)
LW-XP::MAKE-BQ-STRUCT (defined)
LW-XP::BQ-STRUCT-PRINT (defined)
LW-XP::BQ-LIST-TO-VECTOR
LW-XP::BQ-VECTOR
LW-XP::BQ-PRINT (defined)
LW-XP::BQ-ELEMENTS
LW-XP::BQ-STRUCT
LW-XP::BQ-STRUCT-
LW-XP::BQ-STRUCT-P (defined)
LW-XP::BQ-STRUCT-CODE (defined)
LW-XP::BQ-STRUCT-DATA (defined)
SYSTEM::BQ-APPEND (defined)
SYSTEM::BQ-CONS (defined)
SYSTEM::BQ-VECTOR (defined)
SYSTEM::BQ-LIST* (defined)
SYSTEM::BQ-NCONC (defined)
SYSTEM::BQ-LIST (defined)
SYSTEM::*INTERNAL-BQ-FUNCTIONS-ALIST*, value: ((SYSTEM::BQ-LIST* .
CONS) (SYSTEM::BQ-LIST* . LIST*) (SYSTEM::BQ-LIST . LIST)
(SYSTEM::BQ-APPEND . APPEND) (SYSTEM::BQ-NCONC . NCONC)
(SYSTEM::BQ-VECTOR . VECTOR) (SYSTEM::IN-SHARP-LEFT-PAREN .
SYSTEM::IN-SHARP-LEFT-PAREN))

Cheers,
Andrew Kirkpatrick

On 3 August 2017 at 13:06, BusFactor1 Inc. <busfactor1@gmail.com> wrote:
> Hello,
>
> Sometimes I have lists that would be easier to build using the actual symbols (like quote) rather than the quote (‘), backquote (`) and comma (,) characters.  I’m wondering what the names are for the quasi quote and comma symbols expanded by the parser in Lispworks.  A search of the documentation has lead to nothing.
>
> Burton
>
> _______________________________________________
> Lisp Hug - the mailing list for LispWorks users
> lisp-hug@lispworks.com
> http://www.lispworks.com/support/lisp-hug.html

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Re: Quasiquote and Comma symbols

Thank you all for your information and advice.  I was hoping it would be a bit more trivial to use the symbols; but the introspection techniques are quite enlightening.  I’ll use some of those to dig around and see what I can find.


Burton 

> On Aug 3, 2017, at 5:26 AM, 73budden . <budden73@gmail.com> wrote:
> 
> Hi!
> 
> As other people said here, those details are not standardized, and are
> not documented. There are libraries for implementation of quasiquoting
> which (I think) can be made portable. Original implementaiton of
> quasiquote is in CLTL2
> (http://www.cs.cmu.edu/Groups/AI/html/cltl/clm/node367.html#SECTION003600000000000000000
> )
> 
> You can use the original library and/or deduce which structures which
> represent quasiquoted data from the source. If you don't want to go
> this way, you can try further deducing details from the
> implementation.
> 
> I made the following experiment in SBCL:
> 
> 507 CL-USER>(setf *print-pretty* nil)
> NIL
> 508 CL-USER>'``(foo ,(bar ,baz))
> (SB-INT:QUASIQUOTE (SB-INT:QUASIQUOTE (FOO #S(SB-IMPL::COMMA :EXPR
> (BAR #S(SB-IMPL::COMMA :EXPR BAZ :KIND 0)) :KIND 0))))
> 
> So, you might need nested quasiquote to learn something essential. We
> see there are some structures which represent quasiquotes. In an
> open-source implementation
> you can go to the source of the reader (start from the read function
> and the result of (get-macro-character #\`) in your open-source
> implementation).
> 
> I currently have no Lispworks at hand, but you can try similar
> experiments until you can deduce what the exact structure is. You have
> no source codes, but you can use the result of printer output. If
> Lispworks does not show you the unleashed internal structure, try
> using inspector on the data Lispworks creates for you.
> 
> 2017-08-03 6:36 GMT+03:00, BusFactor1 Inc. <busfactor1@gmail.com>:
>> Hello,
>> 
>> Sometimes I have lists that would be easier to build using the actual
>> symbols (like quote) rather than the quote (‘), backquote (`) and comma (,)
>> characters.  I’m wondering what the names are for the quasi quote and comma
>> symbols expanded by the parser in Lispworks.  A search of the documentation
>> has lead to nothing.
>> 
>> Burton
>> 


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