[REBOL] Re: [parse] Special characters in block parsing
From: apwing:zonnet:nl at: 3-Apr-2005 17:12
Volker Nitsch wrote:
>Composing was my first thought too.
>But this looks cleaner (with complex rules):
>
>divide-word: to-lit-word "/"
>probe parse [/][ set word divide-word ]
>probe word
>
>On Apr 3, 2005 4:39 PM, Anton Rolls <[antonr--lexicon--net]> wrote:
>
>>Hi Arie,
>>
>>
>>
>>>>parse [/] compose [set word (to-lit-word first [/])]
>>>>
>>>>
>>== true
>>
>>
>>>>word
>>>>
>>>>
>>== /
>>
>>Anton.
>>
>>
>>
>>>Hi all,
>>>
>>>while experimenting with a small dialect for calculations, I stumbled
>>>into a problem.
>>>
>>>I've done simple things like:
>>>
>>> >> parse [6 * 3] [set num1 number! '* set num2 number! (print num1 *
>>>num2) ]
>>>18
>>>== true
>>>
>>>However, when I try:
>>>
>>> >> parse [6 / 3] [set num1 number! '/ set num2 number! (print num1 /
>>>num2) ]
>>>** Syntax Error: Invalid word-lit -- '
>>>** Near: (line 1) parse [6 / 3] [set num1 number! '/ set num2 number!
>>>(print num1 / num2
>>>) ]
>>>
>>>REBOL complains, because (of course) '/ is not a proper lit-word.
>>>
>>>How can I still parse the / ? I already tried a charset, but I suppose
>>>that's only possible with string-parsing, or not?
>>>
>>>TIA
>>> Arie
>>>
>>>
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>>
>>
>>
>
Hi Anton / Volker,
many thanks for these useful solutions. In my case Volker's solution is
somewhat simpler to use, but I can imagine situations where Anton's
solution might be more appropriate!
I tried both and indeed both do work fine!
What I find strange however is that specifying '/ is an invalid lit-word
but to-lit-word "/" is not.
This looks like a contradiction to me...
Any ideas why this works that way (and I am glad it does ;-) ?
Thanks again!
Arie
