Oh sorry I assumed `o' is short for `out' and `v' for `value', which 
seems not the case.

By the way, in your solution  `fst' and `snd' should be exchanged, i.e.

let a = List.map snd (List.filter (fun x -> fst x) [(out, o); (value, v)])


On 01/20/2012 05:08 PM, Valentin ROBERT wrote:
> Rather (in this case):
>
> let a = List.map fst (List.filter (fun x -> snd x) [(out, o); (value, v)])
>
> That seems reasonable.
>
> On Fri, Jan 20, 2012 at 09:52, Lin <mysnowls@163.com 
> <mailto:mysnowls@163.com>> wrote:
>
>     What about:
>
>     let a = List.filter (fun x -> x)  [out; value]
>
>     Lin
>
>
>
>     On 01/20/2012 02:38 PM, Martin DeMello wrote:
>
>               let a = match (out, value) with
>                 (true, true)  ->  [o; v]
>               | (false, true) ->  [v]
>               | (true, false) ->  [o]
>               | (false, false) ->  []
>
>
>
>
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>