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How do I remove duplication in types?
f#

Hi,

Does someone know how to avoid mentioning "Expression * Expression" multiple times in the following type declaration:

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type Expression = 

    | Variable of string

    | Number of double

    | Add of Expression * Expression

    | Sub of Expression * Expression

    | Mul of Expression * Expression

    | Div of Expression * Expression

There must be a way to avoid declaring Expression * Expression four times.

I mean something like this:

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type Expression = 

    | Variable of string

    | Number of double

    | Add, Sub, Mul of Expression * Expression

Cheers,

HoloEd

.

[Edit: oops, accientally posted twice]

By on 11/19/2008 7:20 PM ()

Hi,
I think that the easiest option would be to represent Add, Sub and Mul as a single binary operator:

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type Operator =
  | Mul | Add | Sub
type Expression = 
  | Variable of string
  | Number of double
  | Binary of Operator * Expression * Expression

T.

By on 11/19/2008 7:20 PM ()

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