[Haskell-beginners] [Haskell-cafe] parser error in pattern

[kolli kolli]

I didnt understand properly but made changes according to what I
understood..Its still giving me the same error

eval1(If t1 t2 t3) =  case (If t1 t2 t3) of
                    eval1(If t1 t2 t3) ->  Just t1


On Mon, Oct 17, 2011 at 4:10 PM, Ivan Lazar Miljenovic <
ivan.miljenovic at gmail.com> wrote:

> On 18 October 2011 09:08, kolli kolli <nammukolli04 at gmail.com> wrote:
> > actual error message is
> >
> > homework2.lhs:137:20: parse error on input `where'
> >
> > data Term = Tru
> >           | Fls
> >           | If Term Term Term
> >           | Zero
> >           | Succ Term
> >           | Pred Term
> >           | IsZero Term
> >           deriving Eq
> >
>
> As I said, the error is from your incorrect usage of the case
> statement; it _should_ look something like:
>
> case foo of
>    bar -> baz
>    bar' -> baz'
>
> >
> >
> >
> >
> > On Mon, Oct 17, 2011 at 4:03 PM, Ivan Lazar Miljenovic
> > <ivan.miljenovic at gmail.com> wrote:
> >>
> >> On 18 October 2011 08:56, kolli kolli <nammukolli04 at gmail.com> wrote:
> >> > after parsing a string i am evaluating it...
> >> > string if t1 then t2 else t3
> >> > my code is
> >> > eval1 :: Term ->  Maybe Term
> >> > eval1(If Tru t2 t3) = Just t2
> >> > eval1(If Fls t2 t3) = Just t3
> >> > eval1(If t1 t2 t3) =  case eval t1
> >> >                     where eval1(If t1 t2 t3) =  Just t1
> >> >
> >> > eval :: Term -> Term
> >> > eval (IsZero Zero) = Tru
> >> > eval (Zero) = Zero
> >> > eval(Pred Zero) = Pred Zero
> >>
> >> Your case statement is incomplete for starters...
> >>
> >> Can you please provide the actual error message as well?  Your
> >> definition of Term would also be useful.
> >>
> >> >
> >> > On Mon, Oct 17, 2011 at 3:46 PM, Ivan Lazar Miljenovic
> >> > <ivan.miljenovic at gmail.com> wrote:
> >> >>
> >> >> On 18 October 2011 08:43, kolli kolli <nammukolli04 at gmail.com>
> wrote:
> >> >> > hey can anyone tell me what is parser error in parser??Plz help me
> >> >> > out
> >> >>
> >> >> It's when the parser can't parse what it's provided.... providing the
> >> >> code that caused the problem and the actual error message is required
> >> >> for a more detailed explanation.
> >> >>
> >> >> --
> >> >> Ivan Lazar Miljenovic
> >> >> Ivan.Miljenovic at gmail.com
> >> >> IvanMiljenovic.wordpress.com
> >> >
> >> >
> >>
> >>
> >>
> >> --
> >> Ivan Lazar Miljenovic
> >> Ivan.Miljenovic at gmail.com
> >> IvanMiljenovic.wordpress.com
> >
> >
>
>
>
> --
> Ivan Lazar Miljenovic
> Ivan.Miljenovic at gmail.com
> IvanMiljenovic.wordpress.com
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.haskell.org/pipermail/beginners/attachments/20111017/81b66853/attachment.htm>