On 2010-04-14 14:58, Ashley Yakeley wrote:
On 2010-04-14 13:59, rocon...@theorem.ca wrote:

There is some notion of value, let's call it proper value, such that
bottom is not one.

In other words bottom is not a proper value.

Define a proper value to be a value x such that x == x.

So neither undefined nor (0.0/0.0) are proper values

In fact proper values are not just subsets of values but are also
quotients.

thus (-0.0) and 0.0 denote the same proper value even though they are
represented by different Haskell values.

The trouble is, there are functions that can distinguish -0.0 and 0.0.
Do we call them bad functions, or are the Eq instances for Float and
Double broken?

Worse, this rules out values of types that are not Eq.

--
Ashley Yakeley

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