Re: Defining a function P[A_ | B_]:=f[A,B] overriding Alternatives

• To: mathgroup at smc.vnet.net
• Subject: [mg19233] Re: Defining a function P[A_ | B_]:=f[A,B] overriding Alternatives
• From: "Allan Hayes" <hay at haystack.demon.co.uk>
• Date: Wed, 11 Aug 1999 02:06:48 -0400
• References: <7oojvg\$i35@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```We do have

p[a_ \[VerticalSeparator] b_] := {a, b}

p[x \[VerticalSeparator] y]

{x, y}

but this may be unsatisfactory in practice.

The alias of  \[VerticalSeparator]  is esc | esc.

Allan
---------------------
Allan Hayes
Mathematica Training and Consulting
Leicester UK
www.haystack.demon.co.uk
hay at haystack.demon.co.uk
Voice: +44 (0)116 271 4198
Fax: +44 (0)870 164 0565

{x, y}
Peltio <peltio at twilight.zone> wrote in message
news:7oojvg\$i35 at smc.vnet.net...
> Is there a general way to call a function with arguments separated not by
> commas but by user defined symbols (particularly Mathematica sacred
symbols)
> ?
> _________________________________________________
>
>
> Here's what I mean:
> I was willing to define a function for the calculation of the conditional
> probabilty, via the Bayes formula, and I wanted to define it in such a way
> that the function call would be:
>
> p[A|B]
>
> but Mathematica correctly interpreted the lhs of the definition
> p[A_|B_] as if there were two alternative arguments.
> I can unprotect Alternatives and clear it and that would work,
>
> Unprotect[Alternatives];
> Clear[Alternatives];
> p[A_|B_]:= {A,B}
>
> p[A|B]
>     {A,B}
>
> but, is there a less traumatic way to achieve this without fully
sacrificing
> Alternatives? It would be fine to avoid its evaluation only when inside a
> [ ] function, by means of upvalues. But the following does not seems to
> work:
>
> Unprotect[Alternatives];
> Alternatives /: p[A_|B_]:={A,B}
>
> And yet I wanted to be able to define my function without showing the
> Alternatives /: part. Is there a way to inhibit the Alternatives
evaluation
> inside p[] in a single statement (that could be hidden in a initialization
> cell)?
>
> Thanks for any help.
> Peltio
> peltio AT usa DOT net
>