Re: Parsing functions - do I need a keyword like 'def' to indicate a function?

M Cleary wrote:
> I'm trying to create a simple scripting language using lex and yacc. I've
> noticed that the grammars for most scripting languages have some kind of
> keyword in front of function declarations. For example:
>
> ruby and python use "def"
> perl uses "sub"
> lua uses "function"
> tcl uses "proc"
>
> for example in python you use: def setColor (r, g, b):
>
> I was wondering why that is. I suspect the point is to avoid of ambiguity
> with other language constructs, but I'm not sure. If possible, I don't want
> to use a keyword. The grammar I want to use for my scripting language would
> go something like this:
>
> func_name '(' param_list ')' IS_TOKEN
> func_body
> END_TOKEN


C doesn't use a keyword when defining functions. Function definitions
usually start with types like "int," but in the original K&R C, that was
optional.


And don't forget FORTRAN statement functions. They didn't need keywords.


And who remembers DCL subroutines? All they needed was a label, RETURN,
and GOSUB.


Note that C is harder to parse than most other languages, and the
FORTRAN parsing algorithm is still named after its inventor.


Louis Krupp

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