Re: [Haskell-cafe] Help me TH code.
2010/10/27 Andy Stewart :
> Serguey Zefirov writes:
>> I think that you should use TH properly, without compiler and logical errors.
>>
>> What actually do you want?
> I'm build multi-processes communication program.
You don't need TH here, I think.
You can write a class Ask:
class Ask a where ask :: YourMonad a
and then instance it:
instance Ask Int where ask = liftIO $ do { putStrLn "Enter integer:";
l <- getLine; return $ read l}
instance Ask Char where ask = liftIO $ do { putStrLn "Enter char:"; l
<- getLine; return $ head l}
instance Ask String where ask = liftIO $ do { putStrLn "Enter
string:"; l <- getLine; return l}
instance (Ask a, Ask b, Ask c) => Ask (a,b,c) where ask = liftIO $ do
{ a <- ask; b <- ask; c <- ask; return (a,b,c)}
You can pass ask values between processes, receiving results of asking.
TH is great and good, but it is that only when you absolutely
exhausted of usual Haskell options.
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Re: [Haskell-cafe] Help me TH code.
Unless you have a 'real' type for parse sometime during compile time, TH
won't be able to generate it. A good rule of thumbs is that if you can't
write the code yourself, then you can't get TH to do it either.
/J
On 27 October 2010 08:50, Andy Stewart wrote:
> Serguey Zefirov writes:
>
> > 2010/10/27 Andy Stewart :
> >> Hi all,
> >>
> >> I want use TH write some function like below:
> >>
> >> data DataType = StringT
> >>| IntT
> >>| CharT
> >>
> >> parse :: [(String,DataType)] -> (TypeA, TypeB, ... TypeN)
> >>
> >> Example:
> >>
> >> parse [("string", StringT), ("001", IntT), ("c", CharT)]
> >>
> >> will return:
> >>
> >> ("string", 001, 'c')
> >>
> >> So how to use TH write 'parse' function?
> >
> > I think that you should use TH properly, without compiler and logical
> errors.
> >
> > What actually do you want?
> I'm build multi-processes communication program.
>
> Example i have two processes : Client and Server.
>
> At Client side, i pass [DataType] to Server, example:
>
> [StringT, IntT, CharT]
>
> Server will handle "user input" with [DataType]
> and return result [String] to Client side, example:
>
> ["string", "001", "c"]
>
> Then at Client side, i need parse [String] to get real value:
>
> ("string", 001, 'c')
>
> Because, [DataType] have many different case, so i want pass [String]
> between processes, and use TH parse result [String] at Client side.
>
> Thanks,
>
> -- Andy
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Re: [Haskell-cafe] Help me TH code.
Serguey Zefirov writes:
> 2010/10/27 Andy Stewart :
>> Hi all,
>>
>> I want use TH write some function like below:
>>
>> data DataType = StringT
>> | IntT
>> | CharT
>>
>> parse :: [(String,DataType)] -> (TypeA, TypeB, ... TypeN)
>>
>> Example:
>>
>> parse [("string", StringT), ("001", IntT), ("c", CharT)]
>>
>> will return:
>>
>> ("string", 001, 'c')
>>
>> So how to use TH write 'parse' function?
>
> I think that you should use TH properly, without compiler and logical errors.
>
> What actually do you want?
I'm build multi-processes communication program.
Example i have two processes : Client and Server.
At Client side, i pass [DataType] to Server, example:
[StringT, IntT, CharT]
Server will handle "user input" with [DataType]
and return result [String] to Client side, example:
["string", "001", "c"]
Then at Client side, i need parse [String] to get real value:
("string", 001, 'c')
Because, [DataType] have many different case, so i want pass [String]
between processes, and use TH parse result [String] at Client side.
Thanks,
-- Andy
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Re: [Haskell-cafe] Help me TH code.
2010/10/27 Andy Stewart :
> Hi all,
>
> I want use TH write some function like below:
>
> data DataType = StringT
> | IntT
> | CharT
>
> parse :: [(String,DataType)] -> (TypeA, TypeB, ... TypeN)
>
> Example:
>
> parse [("string", StringT), ("001", IntT), ("c", CharT)]
>
> will return:
>
> ("string", 001, 'c')
>
> So how to use TH write 'parse' function?
I think that you should use TH properly, without compiler and logical errors.
What actually do you want?
I think that parse should have type (parse :: [(String, DataType)] -> Q Exp).
I think that OverloadedStrings extension should serve you as well.
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