Re: Re: Conca : a small interpreter

Claude Marinier <[email protected]> Wed, 30 Apr 2014 18:53:53 -0400 (EDT)
Newsgroups	gmane.comp.lang.concatenative
Message-ID	<[email protected]>
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On Wed, 30 Apr 2014, [email protected] wrote:
> 
> Interestingly, from the point of view of error checking, the simplified 
> version of my own Furphy (see 
> http://users.beagle.com.au/peterl/furphy.html) doesn't have any possible 
> compile time errors apart from insufficient memory. ALL possible source 
> is syntactically valid, and run time checks are the only meaningful 
> ones! But I also have immediate words to run during compilation to 
> provide syntactic sugar, which not only makes some syntax like matching 
> square brackets and quotation marks necessary, it also provides natural 
> places to test for errors in them. Ideally, the compiler builds up a 
> pretty printed listing as it goes, and syntax failures simply drop error 
> annotations into that while keeping track of the error level reached and 
> making safe-ish default assumptions to try to fill in mismatches; at the 
> end, just before the compiler triggers its compile-and-go run time 
> execution, it should check the error level and only run if an immediate 
> word has specified a safe higher error level than a default of no errors 
> (and there should be a default output of the listing at that stage 
> whether the program runs or not, unless another immediate word has 
> stopped that).
> 
> A good all round guide to this whole area is P.J.Brown's "Writing 
> Interactive Compilers and Interpreters".

I tend to read e-mail from this account in the evening (North America, 
EDT).

I am reading and digesting what you say. That's a lot to think about.

Yes, there is so lottle syntax that all programs are valid. The issue here 
is type checking. At run-time, built-in words check the type of the data 
they use. The dynamic nature of the language make this the default 
behaviour. Static type checking requires knowledge of what the caller 
expects (usually easy) and of what the caller is providing (much more 
difficult).

This is starting to look like "more than I can chew"(1).

Thanks for the comments.

(1) American English has an abundant supply of colourful idiomatic
     expressions.  :-)

-- 
Claude Marinier



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      <p><br>
On Wed, 30 Apr 2014, [email protected] wrote:<br>
&gt; <br>
&gt; Interestingly, from the point of view of error checking, the simplified <br>
&gt; version of my own Furphy (see <br>
&gt; http://users.beagle.com.au/peterl/furphy.html) doesn&#39;t have any possible <br>
&gt; compile time errors apart from insufficient memory. ALL possible source <br>
&gt; is syntactically valid, and run time checks are the only meaningful <br>
&gt; ones! But I also have immediate words to run during compilation to <br>
&gt; provide syntactic sugar, which not only makes some syntax like matching <br>
&gt; square brackets and quotation marks necessary, it also provides natural <br>
&gt; places to test for errors in them. Ideally, the compiler builds up a <br>
&gt; pretty printed listing as it goes, and syntax failures simply drop error <br>
&gt; annotations into that while keeping track of the error level reached and <br>
&gt; making safe-ish default assumptions to try to fill in mismatches; at the <br>
&gt; end, just before the compiler triggers its compile-and-go run time <br>
&gt; execution, it should check the error level and only run if an immediate <br>
&gt; word has specified a safe higher error level than a default of no errors <br>
&gt; (and there should be a default output of the listing at that stage <br>
&gt; whether the program runs or not, unless another immediate word has <br>
&gt; stopped that).<br>
&gt; <br>
&gt; A good all round guide to this whole area is P.J.Brown&#39;s &quot;Writing <br>
&gt; Interactive Compilers and Interpreters&quot;.<br>
<br>
I tend to read e-mail from this account in the evening (North America, <br>
EDT).<br>
<br>
I am reading and digesting what you say. That&#39;s a lot to think about.<br>
<br>
Yes, there is so lottle syntax that all programs are valid. The issue here <br>
is type checking. At run-time, built-in words check the type of the data <br>
they use. The dynamic nature of the language make this the default <br>
behaviour. Static type checking requires knowledge of what the caller <br>
expects (usually easy) and of what the caller is providing (much more <br>
difficult).<br>
<br>
This is starting to look like &quot;more than I can chew&quot;(1).<br>
<br>
Thanks for the comments.<br>
<br>
(1) American English has an abundant supply of colourful idiomatic<br>
     expressions.  :-)<br>
<br>
-- <br>
Claude Marinier<br>
<br>
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