30 Jan
2011
30 Jan
'11
11:23 p.m.
Patrick Browne schrieb:
On 30/01/2011 19:43, Henning Thielemann wrote:
I do not see a constant 1 that is equated with a type.
This is due to my misunderstanding of Haskell. After your comments my understanding of the unit function is as follows:
1) In the instance below the argument for unit must have type LengthInMetres
instance MetricDescription LengthInMetres Metre where
valueInUnit (LengthInMetres d) = d unit l = Metre
2) The constant 1 on the LHS can be replaced _ because it is the fact that unit is defined in this instance the determines the return value.
Btw. the parameter of 'unit' is a lower-case "L" not a One.
3) The RHS is not a type but a constructor.
right