Re: Programming language and IDE design

Martin Ward schrieb:


> The difference is even smaller than this:
>
> DO 10 I = 42.45
> DO 10 I = 42,45
>
> The first is an assignment of a floating point value to variable DO10I,
> the second is a loop with I as the loop variable.
>
> Fortran allows spaces in the middle of identifiers, so requiring
> spaces around keywords does not help (unless you *also*
> disallow spaces within identifiers).
>
> The fact that the two statements can be distinguished with an LL(k)
> parser does not necessarily mean that the language is easy to read.


How would a LL grammar look like, when the lexer returns multiple tokens
for an identifier, here "DO","10" and "I"? With a traditional lexer I'd
suspect that such a language is *context sensitive*, with something else
for "LL(k)".


DoDi
[I suppose the prepass to tell whether it's an assignment is LL(1). You definitely
need to preprocess the statement to tell whether it's an assignment or something
else. After that, the parsing is very easy. -John]

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