Thanks for explaining.
The thing was I thought if SLIF DSL could benefit from less diverse/more
strict — (pseudo-)rule/adverbs only — syntax and model, where
lexeme default statement becomes :lexeme default ::= pseudo rule
inaccessible statement becomes an adverb of
:default and/or :lexeme default pseudo-rules, e.g.
:default action => [name, values] inaccessible => ok
and
named event statement — event ( 'name' | name ) = ( completed | nulled |
predicted ) *symbol* — becomes an adverb of the rule whose LHS *symbol* is,
e.g.
event subtext = completed <subtext>
event 'A[]' = nulled <A>
event '^a' = predicted A
become
subtext ::= ... event completed => subtext
<A> ::= ... event nulled => 'A[]'
A ::= ... event predicted => '^a'
Heretic as it is, but I thought I'd better braindump it. :)
What do you think?
On Tue, Feb 25, 2014 at 8:11 PM, Jeffrey Kegler <
[email protected]> wrote:
> The "logic" goes like this. Note the "=" instead of "::=". This
> signals that the statement is not a rule, and is non-lexical -- it's
> location in the file does not matter. Since it's not a rule, it does not
> take the form LHS ::= RHS2 ...
>
> The initial colon was for pseudo-symbols. Since the lexeme default
> statement is not a rule, it does not have a LHS, so what appears before the
> equal sign ("=") is not considered symbol, pseudo- or otherwise.
>
> I am, frankly, less than 100% happy with this "logic" and my design
> choices, but there they are.
>
> In an ironic way, it does show Marpa's strength. Because it allows and
> exploits ambiguity, I can "unpaint myself out of the corner", by
> introducing new statements and syntax. Languages based on other parsers
> cannot evolve in that way.
>
> -- jeffrey
>
> On 02/25/2014 08:25 AM, Ruslan Shvedov wrote:
>
> Just caught myself thinking that
>
> :default ::= action => [name, values]
> :lexeme default ::= latm => 1
>
>
> looks like a bit more consistent (well, for some definitions of
> consistency at least) syntax than the current
>
> :default ::= action => [name, values]
> lexeme default = latm => 1
>
>
> :default ::= ... and :lexeme ~ ... are pseudo-rules, but lexeme default
> = ... is a statement. This is by design, so I'd appreciate any information
> from those in the know.
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