[Haskell-beginners] print all days of calendar

[Daniel Fischer]

Am Sonntag 20 Dezember 2009 22:11:51 schrieb kane96 at gmx.de:
> I implemented the first step which works if I fix the months (instead of
> the Month Enum) and just return the day and not an element of type Date
>
> this works:
> calendar year = [ day | month <- [Jan, Feb], day <- [1..31],
> legalDate(day,month,year)     == True ]
>
> this doesn't work:
> calendar year = [ Date(day,month,year) | month <- Month, day <- [1..31],
> legalDate(day,month,year)     == True ]

Date was a type synonym for the triple, so
calendar year 
    = [ (day,month,year) | month <- Month, day <- [1..31], legalDate(day,month,year)]

should be what you want.
Note, "condition == True" is better written as "condition".