Yeah, I realized that right after I sent the email (I was composing "on
the fly" and not copy-and-pasting).
I think the main reason I wrote it as an explicit lambda expression rather
than just single = (==) was because I wanted it to parallel the other
definitions. IMO, the preferred way to writ
Hal Daume III wrote:
> I'd like to be able to define something like
> single x = \y -> if x == y then True else False
Just a note on style: it always hurts me to see something like
if term then True else False
-- this is just the same as 'term'.
So you could say
single x = \y -> x==y
MAIL PROTECTED]]
| Sent: 23 April 2002 01:30
| To: Jorge Adriano
| Cc: Haskell Mailing List
| Subject: Re: defining (-> Bool) as a set
|
|
| Yeah, both options suggested are valid, of course. But I
| really don't want to have a constructor and I'm using Edison
| where Coll is d
Yeah, both options suggested are valid, of course. But I really don't
want to have a constructor and I'm using Edison where Coll is defined
something like:
class Coll c e where
empty :: c e
insert :: c e -> e -> c e
etc., which precludes the fun dep solution.
- Hal
--
Hal Daume III
"Co
> class Collection e ce | ce -> e where
> empty :: ce
> insert :: e -> ce -> ce
> member :: e -> ce -> Bool
>
> instance Eq a => Collection a (a -> Bool) where
> empty = (\x -> False)
> insert e f = (\x -> if x == e then True else f x)
> member e f = f e
This is way bette
On Monday 22 April 2002 23:31, Hal Daume III wrote:
> I'd like to be able to define something like
>
> instance Eq a => Coll (-> Bool) a where
> empty= \_ -> False
> single x = \y -> if x == y then True else False
> union a b = \x -> a x || b x
> insert s x = \y -> x == y || s y
>
> an
Hal Daume III <[EMAIL PROTECTED]> writes:
> I'd like to be able to define something like
>
> instance Eq a => Coll (-> Bool) a where
> empty= \_ -> False
> single x = \y -> if x == y then True else False
> union a b = \x -> a x || b x
> insert s x = \y -> x == y || s y
I don't know
I'd like to be able to define something like
instance Eq a => Coll (-> Bool) a where
empty= \_ -> False
single x = \y -> if x == y then True else False
union a b = \x -> a x || b x
insert s x = \y -> x == y || s y
and the like
However, this seems to be impossible. Is this the type
