Jeff Heard wrote:
It is parametrically polymorphic in a. And no, it's an arbitrary
decision, BUT... it allows me and other users to define generally
useful behaviours and widgets to package with the library using the
basic types without locking down 'a'. The EventData type looks like
this:
data Event a { ..., edata :: EData a, ... }
data EData a = EChar Char
| EString String
| EStringL [String]
| EByteString ByteString
| EByteStringL [ByteString]
| EInt Int
| EIntL [Int]
| EDouble Double
| EDoubleL [Double]
| EBool Bool
| EBoolL [Bool]
| EOther a
| EOtherL [a]
Maybe I wasn't clear, and probably I'm being dense. I understand what
you've done - I looked at the type declarations before commenting - but
I don't understand why.
Why is it useful to be able to use basic types without locking down 'a'?
Why is it useful to have a value of type "Event FooBar" which, in
apparent defiance of the FooBar parameter, actually contains a value of
type Double?
Jules
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