[clean-list] questions

[Tomasz Zielonka]

On Thu, Nov 20, 2003 at 05:26:36PM +0100, Jenda Krynicky wrote:
> 
> If e.g. I want to make sure that the stuff entered by the user is a 
> date in YYYY-MM-DD format I definitely do not want to spend twenty 
> cryptic lines writing a parser where
> 	/^(\d{4})-(\d{1,2})-(\d{1,2})$/
> suffices. (I know you need to make sure the month is between 1 and 12 
> and the day is reasonable, but you'd do that outside the parser as 
> well.)

date = do
    yyyy <- count 4 digit
    char '-'
    mm <- count 2 digit
    char '-'
    dd <- count 2 digit
    return (yyyy, mm, dd)

Is it really so long and cryptic?
You get reusability and compositionality for free.

Best regards,
Tom

-- 
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