Digest #115 2020-09-02
Contributions
proposal - Traverse-wordlist does not find unnamed/unfinished definitions
Author:
M. Anton Ertl
Change Log:
Initial version
Problem:
Does TRAVERSE-WORDLIST find unfinished or nameless definitions?
Solution:
It does not.
Proposal:
Change
Execute xt once for every word in the wordlist wid,
into
Execute xt once for every named and findable word in the wordlist wid,
Discussion
This is a wording change. The use of "findable" is taken from it's use in the definition of ":" an DOES>. Possible problem: A shadowed word is not findable with FIND, FIND-NAME-IN etc, but may be reached with TRAVERSE-WORDLIST.
proposal - XML Forth Standard - migration from LaTeX to DocBook
Author:
Peter Knaggs
Problem & Solution:
The author, who is also the editor of the Forth Standard is considering migrating from LaTeX to XML. The idea being that XML is easier to parse for machines while maintaining being editable by humans. Please read the proposed PDF. More material including DTD, TEX, HTML and the XML example below.
Tools:
I have been thinking of using either XML Notepad or XXE (XMLmind XML Editor) as the editor environment and move the whole standard into DocBook. That way I get PDF, XHTML and EPUB with very little work.
Feedback:
At this stage the author is asking for feedback:
- How do you like the XML definition for words?
- Would your system/documentation also output this XML definitions for its own words?
- Any other related feedback?
Example Code:
\<wordlist\>
<worddef name="DOES>" id="core:DOES" number="1250" wordlist="CORE" english="does">
\<description\>
\<interpret\>
Interpretation semantics for this word are undefined.
</interpret>
\<compile\>
<stack type="C">
\<pre\>colon-sys_1</pre>
\<post\>colon-sys_2</post>
</stack>
\<para\>
Append the run-time semantics below to the current
definition.
Whether or not the current definition is rendered
findable in the dictionary by the compilation of
<word word="core:DOES" /> is implementation defined.
Consume \<param\>colon-sys_1</param> and produce
\<param\>colon-sys_2</param>. Append the initiation
semantics given below to the current definition.
</para>
</compile>
\<runtime\>
\<stack\></stack>
<stack type="R">\<pre\>next-sys_1</pre></stack>
\<para\>
Replace the execution semantics of the most recent
definition, referred to as \<param\>name</param>, with
the \<param\>name</param> execution semantics given
below. Return control to the calling definition
specified by \<param\>nest-sys_1</param>. An ambiguous
condition exists if \<param\>name</param> was not
defined with <word word="core:CREATE" /> or a
user-defined word that calls <word word="core:CREATE"/>.
</para>
</runtime>
\<init\>
\<stack\>
\<pre\>i*x</pre>
\<post\>i*x a-addr</post>
</stack>
<stack type="R">
\<post\>next-sys_1</post>
</stack>
\<para\>
Save implementation-dependent information
\<param\>nest-sys_2</param> about the calling definition.
Place \<param\>name</param>'s data field address on the
stack. The stack effects \<param\>i*x</param> represent
arguments to \<param\>name</param>.
</para>
</init>
<execute type="name">
\<stack\>
\<pre\>i*x</pre>
\<post\>j*x</post>
</stack>
\<para\>
Execute the portion of the definition that begins with
the initiation semantics appended by the
<word word="core:DOES" /> which modified
\<param\>name</param>. The stack effects \<param\>i*x</param>
and \<param\>j*x</param> represent arguments to and
results from \<param\>name</param>, respectively.
</para>
</execute>
\<see\>
<wref word="core:CREATE" />
</see>
</description>
\<rationale\>
\<para\>
Typical use:
\<c\>: X ... DOES> ... ;</c>
</para>\<para\>
Following <word word="core:DOES" />, a Standard Program
may not make any assumptions regarding the ability to find
either the name of the definition containing the
<word word="core:DOES"/> or any previous definition whose
name may be concealed by it. <word word="core:DOES" />
effectively ends one definition and begins another as far
as local variables and control-flow structures are
concerned.
The compilation behavior makes it clear that the user is
not entitled to place <word word="core:DOES"/> inside any
control-flow structures.
</para>
</rationale>
\<testing\>
\<test\>\<pre\>: DOES1 DOES> @ 1 + ;</pre>\<post\></post></test>
\<test\>\<pre\>: DOES2 DOES> @ 2 + ;</pre>\<post\></post></test>
\<test\>\<pre\>CREATE CR1</pre>\<post\> </post></test>
\<test\>\<pre\>CR1 </pre>\<post\>HERE</post></test>
\<test\>\<pre\>1 , </pre>\<post\> </post></test>
\<test\>\<pre\>CR1 @</pre>\<post\>1</post></test>
\<test\>\<pre\>DOES1</pre>\<post\> </post></test>
\<test\>\<pre\>CR1 </pre>\<post\>2</post></test>
\<test\>\<pre\>DOES2</pre>\<post\> </post></test>
\<test\>\<pre\>CR1 </pre>\<post\>3</post></test>
\<test\>\<pre\>: WEIRD: CREATE DOES> 1 + DOES> 2 + ;</pre>\<post\></post></test>
\<test\>\<pre\>WEIRD: W1</pre>\<post\></post></test>
\<test\>\<pre\>' W1 >BODY</pre>\<post\>HERE </post></test>
\<test\>\<pre\>W1 </pre>\<post\>HERE 1 +</post></test>
\<test\>\<pre\>W1 </pre>\<post\>HERE 2 +</post></test>
</testing>
</worddef>
</wordlist>
Replies
An implementation by Andrew Haley can be found here: https://sourceforge.net/projects/concurrentforth/
Replace the parenthesis text “(according to the rules in the system's FIND)” with “in the current search order”. Since we don't have a term “search order” in the definitions of terms, section 2, only in the search order word set, move that to the definition of terms, and change it:
search order: A list of word lists specifying the order in which the dictionary will be searched. If the search order wordset is not present, the search order consists of all the word lists that contain definitions.
to the definitions of terms.
Vocabulary proposal
version uh 2019-09-18
Add the following section to the Forth-200x standard in the optional Search-Order word set to the Search-Order extension word list.
16.6.2.3000 VOCABULARY
( "<spaces>name" -- )
Skip leading space delimiters. Parse name delimited by a space. Create a definition for name with the execution semantics defined below. Create a new empty word list wid and associate it with name.
name is referred to as a "vocabulary".
name Execution:
( -- )
Replace the first word list in the search order by the word list wid that is associated with the vocabulary.
An ambiguous condition exists if there are no word lists in the search order.
See: 16.6.1.2460 WORDLIST 16.6.2.0715 ALSO 16.6.2.2038 PREVIOUS 16.6.1.2195 GET-ORDER 16.6.1.2197 SET-ORDER
Rationale: VOCABULARY has been used in traditional Forth systems and it is available with consistent behaviour in many standard systems. So it seems worthwhile to standardize it (again, it has been standardized in Forth-83).
Typical use:
VOCABULARY Assembler
ONLY FORTH ALSO Assembler DEFINITIONS ( set search order to ... FORTH Assembler Assembler )
Reference Implementation:
: VOCABULARY ( -- )
WORDLIST CREATE ,
DOES> ( -- ) @
>R GET-ORDER SWAP DROP
R> SWAP SET-ORDER ;
Other additions
Add the following ambigous condition to 16.4.1.2:
- executing a vocabulary word when the search order is empty (16.6.2.3000)
Addressed in this proposal.
Replace the text
Return a true flag if name is the name of a word that can be found (according to the rules in the system's FIND); otherwise return a false flag.
with
Try to find name. Return a true flag if name can be found; otherwise return a false flag.
Add the following redefinition of the term “find” to 16.2:
find: To search the search order for a definition name matching a given string.
Cross-reference 2.1 find and 16.2 find.