Am Montag, den 07.11.2011, 21:41 +0000 schrieb Barney Hilken:
The problem with this approach is that different labels do not have different representations at the value level.
I think this is an advantage, because it means you don't have to carry this stuff about at runtime.
This allows me to pattern match records, since I can construct record patterns that contain fixed labels:
X :& MyName1 := myValue1 :& MyName2 := myValue2
I cannot see how this could be done using kind String. Do you see a solution for this?
A similar problem arises when you want to define a selector function. You could implement a function get that receives a record and a label as arguments. However, you could not say something like the following then:
get myRecord MyName1
Instead, you would have to write something like this:
get myRecord (Label :: MyName1)
Just define a constant
myName1 = Label :: MyName1
for each label you actually use, and you can use it in both get and pattern matching
You cannot use such a constant in a pattern. You need a data constructor if you want to use pattern matching. Best wishes, Wolfgang