On 01/07/10 13:11, Patrick Browne wrote:
Neil,
Does the following sum up the situation?
The class Num has subclasses containing various numeric types and the
literal 1 is a value for one or more of those types.
Hence the Haskell compiler says the instance 1) is OK.
But at run time, without the qu
The class Num has subclasses containing various numeric types and the
literal 1 is a value for one or more of those types.
Well, the problem is not with subclasses, but with types.
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Patrick Browne writes:
> Why do some cases such as 1) fail to run even if they are the only
> instantiation.
I think this is because literal numbers are polymorphic, i.e. a '1' in
your source code is shorthand for 'fromIntegral 1', which is a type of
Num a => a. Thus, 'spatialLocation 1' doesn'
Neil,
Does the following sum up the situation?
The class Num has subclasses containing various numeric types and the
literal 1 is a value for one or more of those types.
Hence the Haskell compiler says the instance 1) is OK.
But at run time, without the quantified (1:Int), the 1 could of more
than
On 01/07/10 12:37, Patrick Browne wrote:
Why do some cases such as 1) fail to run even if they are the only
instantiation.
-- 1) Compiles but does not run
instance LocatedAt Int String where
spatialLocation(1)="home"
That instance is fine. I presume the problem is that you are trying
Hi,
My understanding of functional dependencies is that they can be used to
ensure that one type depends on another type.
For example, the type of location depends could on the type of the
object at that location.
Consider two models
1) The location of an aircraft landing should have location of th
