[1] http://www.haskell.org/pipermail/haskell-cafe/2004-March/005988.html
in response to which, SPJ pointed out that a Set cannot be a Monad: [2] http://www.haskell.org/pipermail/haskell-cafe/2004-March/005995.html
I found myself treading a path which led me to asking the same question as [1]. Given the answer [2], I'd like to stand back a little and ask if there's another way to tackle my niggle: what I'm interested in is a set comprehension expression that is analogous to a list comprehension expression; e.g. in:
[[ > import Data.Set > > type AtomicConcept = String -- named atomic concept > type AtomicRole = String -- named atomic role > > type AtomicConcepts a :: AtomicConcept -> (Set a) > type AtomicRoles a :: AtomicRole -> (Set (a,a)) > > type Interpretation a :: (Set a,AtomicConcepts a,AtomicRoles a)
...
> iAL (idom,ic,ir) (ALAll r c) = mkSet [ a | (a,b) <- setToList (ir r) > , b `elementOf` ir c ] ]]
is there a common or similar idiom to achieve the same effect without converting the set to a list and back?
I did also find myself wondering if there was a role for unfold (or similar) here.
#g
------------ Graham Klyne For email: http://www.ninebynine.org/#Contact
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