Re: [Caml-list] AST and "when"

[Mike Potanin <potanin@mccme.ru>]

On Wed, 29 Jan 2003, Olivier Andrieu wrote:

Whether I can make "formula" quotation so it compile
 match e with
  <:formula< sin(@x) ^ 2 + cos(@x) ^ 2 >> -> <:formula< 1 >>
to
 match e with
  (Sum [(Pow1 (Sin x) 2); (Pow1 (Cos x_temp) 2)]) when x==x_temp
     -> Const 1
Or I mast write
 match e with
  <:formula< sin(@x) ^ 2 + cos(@y) ^ 2 >> when x==y
     -> <:formula< 1 >>

>  Mike Potanin [Wednesday 29 January 2003] :
>
> I don't think so: in `a when a<0', only the first `a' is a pattern,
> the when + expr is part of the `match' (or `try' or `function')
> construct which is at the expression level.
>
>  > (MLast.PaLid ((0, 0), "a"),
>  >   Some
>  >    (MLast.ExApp ((0, 0),
>  >      MLast.ExApp ((0, 0), MLast.ExLid ((0, 0), "<"),
>  >       MLast.ExLid ((0, 0), "a")),
>  >      MLast.ExInt ((0, 0), "0")))
>
> that's not a single pattern (MLast.patt), that's a tuple of type
> `MLast.patt * MLast.expr option'

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