[racket] the definition of 'form'?

I don't think this is really what Norman wants.  Instead, I think he's
looking for a definition of `form` as it appears in various error
messages that mention "form".

Sam



On Fri, May 16, 2014 at 1:52 PM, Ryan Culpepper <ryanc at ccs.neu.edu> wrote:
> If you refer to the "Syntax Model" section of the reference
> (http://docs.racket-lang.org/reference/syntax-model.html), you'll see that
> Racket syntax is defined by two passes, called "read" and "expand".
>
> The grammar you gave in your message is what I would call a "term"---it's
> anything that the read pass can turn into a syntax object. In other words,
> terms are what syntax objects represent.
>
> The word "form" generally means any of the non-terminals of the Racket
> language that the macro expander cares about, such as "expression forms" and
> "definition forms". There are also "module-level forms", which include
> require and provide. There's a list of these nonterminals in the subsection
> "Fully Expanded Programs"
> (http://docs.racket-lang.org/reference/syntax-model.html#%28part._fully-expanded%29).
> You can think of the syntax of Racket roughly as that grammar with "or a
> macro that eventually expands into one of the above" added to every
> production there---except the one for "formals". The "formals" non-terminal
> doesn't correspond to an expansion context, nor do "module-path" or
> "raw-require-spec"; thus, they are not considered forms. Neither is
> something like "cond-clause", for example; it's just an auxiliary
> non-terminal for the "cond" macro.
>
> To complicate matters, macros can also create new expansion contexts and
> thus new kinds of forms. For example, the class macro introduces "class-body
> forms", which include expressions and definitions as well as other syntaxes
> that are only significant immediately within class bodies, such as "init"
> and "abstract" forms.
>
> Ryan
>
>
>
> On 05/16/2014 12:28 PM, Norman Ramsey wrote:
>>
>> Where would I find out, preferably in the Racket documentation,
>> the definition of what a 'form' is?  I'm thinking along these lines:
>>
>>    A form is one of:
>>      - a symbol
>>      - a numeric literal
>>      - a string literal
>>      - ... possibly other literals? ...
>>      - a sequence of forms wrapped in one pair of parentheses
>>
>> Is this the right idea?  Or is the word 'form' reserved only for
>> things wrapped in parentheses?
>>
>>
>> Norman
>>
>>
>> P.S. In the Racket documentation, I found the section on 'Syntactic
>> Forms', but I haven't found a definition of what a form is, and I
>> haven't found the word 'form' in the index.
>>
>>
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