[Haskell-cafe] Re: uu-parsinglib pKeyword

[Ozgur Akgun]

Even though it was nice to see how it can be implemented, I'll be using the
"PS" version :)
I was really close in implementing it myself.

Anyway thanks for the quick reply.

2009/10/28 S. Doaitse Swierstra <doaitse at cs.uu.nl>

> pToken []     = pSucceed []
> pToken (x:xs) = (:) <$> pSym x <*> pToken xs
>
> pKeyword_Float = pToken "Float"
> etc
>
> Doaitse
>
> PS: this function has been defined in the module
> Text.ParserCombinators.UU.Derived
>
>
>
>
> On 28 okt 2009, at 17:39, Ozgur wrote:
>
>  Hi everybody,
>>
>> I am using the uu-parsinglib to parse a structured language and map
>> the results to some proper data structures. Thanks to Prof Doaitse
>> Swierstra (and other authors if any), it is fun to write a parser
>> using this library.
>>
>> I've been sending private mails to Doaitse about my questions, who
>> kindly gives nice replies everytime. But this time I thought I can ask
>> my question to the community, and give everyone the chance to benefit
>> from the answers.
>>
>> [After the intro, here comes my real question]
>>
>> I am trying to capture the following pattern.
>>
>> pKeyword_Int = ( \ _ _ _ -> "int" ) <$> pSym 'i' <*> pSym 'n' <*> pSym
>> 't'
>> pKeyword_Float = ( \ _ _ _ _ _ -> "float" ) <$> pSym 'f' <*> pSym 'l'
>> <*> pSym 'o' <*> pSym 'a' <*> pSym 't'
>>
>> As you can see there is an obvious pattern if you try to capture a
>> "keyword". If there were a function called pKeyword taking a string as
>> an argument and producing the necessary parser, things would be
>> easier.
>>
>> What I mean is,
>>
>> pKeyword_Int = pKeyword "int"
>> pKeyword_Float = pKeyword "float"
>>
>> I tried to create this pKeyword function myself but I couldn't manage
>> to do it.
>>
>> I can feel that, one can simply add a "<* pReturn []" to the ends of
>> every parser and write a recursion with this base condition.
>>
>> Any suggestions?
>>
>> PS: Actually I'm a little bit uncomfortable since there may be such a
>> function in the library already :)
>>
>
>


-- 
Ozgur Akgun
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