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From: Leonid Shifrin on 8 Apr 2010 07:59
Hi Leo,

Why not use

{__Integer?NonNegative}

Regards,
Leonid


On Wed, Apr 7, 2010 at 6:25 AM, Leo Alekseyev <dnquark(a)gmail.com> wrote:

> I don't know why I didn't think about _?. How silly of me!
>
> Since I want to also enforce the Integer property, what I need is
> MatchQ[{1, 2}, {_?(NonNegative[#] && Head[#] === Integer &) ..}]
>
> I am guessing this is the cleanest way to do it...
>
>
> On Wed, Apr 7, 2010 at 6:07 AM, dh <dh(a)metrohm.com> wrote:
> > On 07.04.2010 09:20, Leo Alekseyev wrote:
> >>
> >> This seems like a very basic pattern-matching question, but somehow
> >> the answer eludes me at the moment. I want to match a list of
> >> non-negative integers. Something like MatchQ[{1,2},{(x_Integer /; x
> >>>
> >>> = 0)..}] doesn't work -- do named patterns simply not play well with
> >>
> >> Repeated[]?..
> >>
> >> After starting to write this message, the following pattern, occurred to
> >> me:
> >> MatchQ[{2, 3}, x : {_Integer ..} /; ! MemberQ[x, y_ /; Negative[y]]]
> >> -- this works, but seems needlessly complex -- so I'll send the
> >> message on, in hopes that there is a cleaner way of writing the
> >> pattern.
> >>
> > Hi Leo,
> > if you repeat something like x_ .., you repeat the x, that is all the
> > elements must be the same. Therefore, do not name the pattern. The
> following
> > will work:
> > MatchQ[{1, 2}, {_ ?NonNegative ..}]
> >
> > cheers, Daniel
> >
> >
> > --
> >
> > Daniel Huber
> > Metrohm Ltd.
> > Oberdorfstr. 68
> > CH-9100 Herisau
> > Tel. +41 71 353 8585, Fax +41 71 353 8907
> > E-Mail:<mailto:dh(a)metrohm.com>
> > Internet:<http://www.metrohm.com>
> >
> >
>
>
From: Raffy on 8 Apr 2010 08:00
On Apr 7, 4:27 am, dh <d...(a)metrohm.com> wrote:
> On 07.04.2010 09:20, Leo Alekseyev wrote:> This seems like a very basic pattern-matching question, but somehow
> > the answer eludes me at the moment. I want to match a list of
> > non-negative integers. Something like MatchQ[{1,2},{(x_Integer /; x
> >> = 0)..}] doesn't work -- do named patterns simply not play well with
> > Repeated[]?..
>
> > After starting to write this message, the following pattern, occurred to me:
> > MatchQ[{2, 3}, x : {_Integer ..} /; ! MemberQ[x, y_ /; Negative[y]]]
> > -- this works, but seems needlessly complex -- so I'll send the
> > message on, in hopes that there is a cleaner way of writing the
> > pattern.
>
> Hi Leo,
> if you repeat something like x_ .., you repeat the x, that is all the
> elements must be the same. Therefore, do not name the pattern. The
> following will work:
> MatchQ[{1, 2}, {_ ?NonNegative ..}]
>
> cheers, Daniel
>
> --
>
> Daniel Huber
> Metrohm Ltd.
> Oberdorfstr. 68
> CH-9100 Herisau
> Tel. +41 71 353 8585, Fax +41 71 353 8907
> E-Mail:<mailto:d...(a)metrohm.com>
> Internet:<http://www.metrohm.com>

MatchQ[ {1,2}, {_Integer?NonNegative..} ]

MatchQ[ {1,2}, {x__Integer /; NonNegative(a)Min[x]} ]

From: Carl K. Woll on 8 Apr 2010 08:03
On 4/7/2010 3:20 AM, Leo Alekseyev wrote:
> This seems like a very basic pattern-matching question, but somehow
> the answer eludes me at the moment. I want to match a list of
> non-negative integers. Something like MatchQ[{1,2},{(x_Integer /; x
>
>> = 0)..}] doesn't work -- do named patterns simply not play well with
>>
> Repeated[]?..
>
>
Yes. The named pattern must be the same, so only {1,1} would match.
Instead you can use PatternTest:

MatchQ[{1,2}, {_Integer?(#!=0&) .. }]

Of course, simpler is to use:

MatchQ[{1,2}, {__Integer?NonNegative}]

Carl Woll
Wolfram Research

> After starting to write this message, the following pattern, occurred to me:
> MatchQ[{2, 3}, x : {_Integer ..} /; ! MemberQ[x, y_ /; Negative[y]]]
> -- this works, but seems needlessly complex -- so I'll send the
> message on, in hopes that there is a cleaner way of writing the
> pattern.
>
>

From: Raffy on 10 Apr 2010 06:53
On Apr 8, 5:03 am, "Carl K. Woll" <ca...(a)wolfram.com> wrote:
> On 4/7/2010 3:20 AM, Leo Alekseyev wrote:> This seems like a very basic p=
attern-matching question, but somehow
> > the answer eludes me at the moment. I want to match a list of
> > non-negative integers. Something like MatchQ[{1,2},{(x_Integer /; x
>
> >> = 0)..}] doesn't work -- do named patterns simply not play well with
>
> > Repeated[]?..
>
> Yes. The named pattern must be the same, so only {1,1} would match.
> Instead you can use PatternTest:
>
> MatchQ[{1,2}, {_Integer?(#!=0&) .. }]
>
> Of course, simpler is to use:
>
> MatchQ[{1,2}, {__Integer?NonNegative}]
>
> Carl Woll
> Wolfram Research
>
>
>
> > After starting to write this message, the following pattern, occurred t=
o me:
> > MatchQ[{2, 3}, x : {_Integer ..} /; ! MemberQ[x, y_ /; Negative[y]]]
> > -- this works, but seems needlessly complex -- so I'll send the
> > message on, in hopes that there is a cleaner way of writing the
> > pattern.

I was surprised that __?Test works properly by applying the test to
each element of the matched sequence.

I would not of expected this behavior, however, after looking, it does
appear in the documentation.

Thanks.

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