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Question about overloaded operators
f#

Hi,

I have tried using the following :

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let f data1 data2 = Array.map2 (fun e1 e2 -> e1 - e2) data1 data2 ;;

(* other failed try *)
let f data1 data2 = Array.map2 (-) data1 data2 ;;

But this will infer that data1 and data2 have type int array unless I use an explicit type annotation (e.g. float array but not 'a array). I have tried defining local inline function as the one specified in the FSLib (let (-) (x: ^a) (y: ^b) : ^c = ... But this won't work.

Is there a way around ?

Thanks a lot.

Julien

.

If you want a function that works on float[], then just add the type annotation.

If you want a function that works on any type 'a[], where 'a supports the given overloaded subtraction operator, then there are two choices:

  • pass in the "subtract" function as an argument, e.g. "let f (-) data1 data2 = ..."
  • use "let inline f data1 data2 = ...", which delays commitment as to which operator is used through the use of code duplication (a bit like C++ templates). This is not really recommended for widespread use in your code, partly because it is not possible to use the same trick on type definitions, but is very effective in corner cases.

Cheers,

Don

By on 11/11/2006 5:59 PM ()

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