SyntaxInformation Question [Mathematica]

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From: E. Martin-Serrano on 5 Jul 2010 06:02

Hi,

In the ref/SyntaxInformation in the Help there is the following example or
explanation can be found:

"f can have any number of arguments, but each should be a two-element list:"

SyntaxInformation[f] = {"ArgumentsPattern" -> {{_, _} ...}};

{f[{x, y}, {a, b}], f[x, {a, b}, {x, y, z}]};

In the first part of the example: 'f[{x, y}, {a, b}]', the list =91{x, y}' is
a two - elements list, so is '{a, b}', then syntax constrain holds and it is
understandable for me.

In the second part of the example: 'f[x, {a, b}, {x, y, z}]', the symbol '
x=92 evaluates to a list but not necessarily to a 'two - elements list' as
demanded in the SyntaxInformation[f] = {"ArgumentsPattern" -> {{_, _} ...}}
declaration. According to the scarce explanation in the example it is not
excluded for 'x' to evaluate to a '12 - elements list=92 {x, y}'; however the
syntax constrain allows it to pass; following with the example the list '
{a, b}' is again a two - elements list, so it pass the check. But finally
'{x, y, z}' is a three elements list but it is allowed to pass the constrain
too; and so do {v, x, y, z}, and {u, v, x, y, z}, and any list of whatever
any other length as this {f[{x, y}, {a, b}], f[x, {a, b},
Sequence@@Array[x&, 100]]}.

In the example

Options[f]={aaa->1,bbb->2,ccc -> 4};

SyntaxInformation[f]={"ArgumentsPattern"->{_,_,OptionsPattern[]}};

The syntax specification allows for two parameters and a list of options to
be submitted to the function =91f[]=92.

The following does work as expected since the following is allowed to pass
it is right since just two parameters and a list of options are submitted as
specified)

f[x,y, aaa->2,bbb->3,ccc ->4];

But the following is allowed to pass too, despite, in this case, 6
parameters *x, y, z, k, l, m* (plus the options) are submitted instead of
just the two specified parameters.

f[x, y, z, k, l, m, aaa->2,bbb->3,ccc->4];

When I say they pass, I mean nothing is colored red saying that something is
syntactically wrong and must be corrected..

I am certainly missing something important here and, clearly I do not
understand the explanation given to this very basic programming command. So
I would appreciate any clarification or help from the group.

Or maybe Wolfram should provide a complete tutorial on it or a clearer
explanation.

This occurs in version 7.0.1. for Windows XP SP3.

E. Martin-Serrano

___________________________________________________

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<body lang=EN-US link=blue vlink=purple>

<div class=Section1>

Hi,<o:p></o:p>

<o:p> </o:p>

In the =
ref/SyntaxInformation
in the Help there is the following example or explanation can be =
found:<o:p></o:p>

<o:p> </o:p>

"f can have
any number of arguments, but each should be a two-element list:" =
<o:p></o:p>

<o:p> </o:p>

SyntaxInformation[f] =
{"ArgumentsPattern" -> {{_, _} =
....}};<o:p></o:p>

<o:p> </o:p>

{f[{x, y}, {a, =
b}], f[x,
{a, b}, {x, y, z}]};<o:p></o:p>

<o:p> </o:p>

In the first =
part of the
example: 'f[{x, y}, {a, b}]', the list ‘{x, y}' is a two - =
elements
list, so is '{a, b}', then syntax constrain holds and it is =
understandable for
me.<o:p></o:p>

<o:p> </o:p>

In the second =
part of the
example: 'f[x, {a, b}, {x, y, z}]', the symbol ' x’ evaluates to a =
list
but not necessarily to a 'two - elements list' as demanded in the =
SyntaxInformation[f]
= {"ArgumentsPattern" -> {{_, _} ...}} declaration. =
According to
the scarce explanation in the example it is not excluded for 'x' to =
evaluate to
a '12 - elements list’ {x, y}'; however the syntax constrain =
allows it to
pass; following with the example the list ' {a, b}' is again a two - =
elements
list, so it pass the check. But finally '{x, y, z}' is a three elements =
list
but it is allowed to pass the constrain too; and so do {v, x, y, z}, and =
{u, v,
x, y, z}, and any list of whatever any other length as this {f[{x, y}, =
{a, b}],
f[x, {a, b}, Sequence@@Array[x&, =
100]]}.<o:p></o:p>

<o:p> </o:p>

In the example =
<o:p></o:p>

<o:p> </o:p>

Options[f]={aaa->1,bbb->2,ccc
-> 4};<o:p></o:p>

<o:p> </o:p>

SyntaxInformation[f]={"ArgumentsPattern=
"->{_,_,OptionsPattern[]}};
<o:p></o:p>

<o:p> </o:p>

The syntax =
specification allows
for two parameters and a list of options to be submitted to the function
‘f[]’.<o:p></o:p>

<o:p> </o:p>

The following =
does work
as expected since the following is allowed to pass it is right since =
just two
parameters and a list of options are submitted as =
specified)<o:p></o:p>

<o:p> </o:p>

f[x,y,
aaa->2,bbb->3,ccc ->4];<o:p></o:p>

<o:p> </o:p>

But the =
following is
allowed to pass too, despite, in this case, 6 parameters *x, y, z, k, l, =
m* (plus
the options) are submitted instead of just the two specified =
parameters.<o:p></o:p>

<o:p> </o:p>

f[x, =
y, z, k, l,
m, aaa->2,bbb->3,ccc->4];<o:p></o:p>

<o:p> </o:p>

When I say =
they pass, I
mean nothing is colored red saying that something is syntactically wrong =
and
must be corrected.. <o:p></o:p>

<o:p> </o:p>

I am certainly =
missing
something important here and, clearly I do not understand the =
explanation given
to this very basic programming command. So I would appreciate any =
clarification
or help from the group.<o:p></o:p>

<o:p> </o:p>

Or maybe Wolfram should provide a complete tutorial on it or a =
clearer
explanation.<o:p></o:p>

<o:p> </o:p>

This occurs in version 7.0.1. for Windows XP =
SP3.<o:p></o:p>

<o:p> </o:p>

E. Martin-Serrano<o:p></o:p>

<o:p> </o:p>

<o:p> </o:p>

___________________________________________________</s=
pan><o:p></o:p>

 <o:p></o:p>

This e-mail and the documents attached are confidential and =
intended
solely for the addressee; it may also be privileged. If you receive this =
e-mail
in error, please notify the sender immediately and destroy it. As its =
integrity
cannot be secured on the Internet, E. Mart=EDn-Serrano liability =
cannot be
triggered for the message content. Although the sender endeavors to =
maintain a
computer virus-free network, the sender does not warrant that this
transmission is virus-free and will not be liable for any damages =
resulting
from any virus transmitted. 
 
Este mensaje y los ficheros adjuntos pueden =
contener
informaci=F3n confidencial  destinada solamente a la(s) persona(s)
mencionadas anteriormente pueden estar protegidos por secreto =
profesional y en
cualquier caso el mensaje en su totalidad est=E1  amparado y =
protegido por
la legislaci=F3n vigente que preserva el secreto de las comunicaciones, =
y por la
legislaci=F3n de protecci=F3n de datos de car=E1cter personal. Si usted =
recibe este
correo electr=F3nico por error, gracias por informar  =
inmediatamente al
remitente y destruir el mensaje. Al no estar asegurada la integridad de =
este
mensaje sobre la red, E. Mart=EDn-Serrano no se hace responsable por su =
contenido.
Su contenido no constituye ning=FAn compromiso para el remitente, =
salvo
ratificaci=F3n escrita por ambas partes. Aunque se esfuerza al =
m=E1ximo por
mantener su red libre de virus, el emisor no puede garantizar nada al =
respecto
y no ser=E1 responsable de cualesquiera da=F1os que puedan resultar de =
una
transmisi=F3n de virus. <o:p></o:p></p=
>

<o:p> </o:p>

</div>

</body>

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From: E. Martin-Serrano on 5 Jul 2010 21:13

Hi,

Sorry for the previous post that looks almost unreadable on my screen
probably due to problems with hidden special characters which distort the
page format and others. I hope this one reads better.

__________________________________________________

In the ref/SyntaxInformation in the Help the following example can be found:

"f can have any number of arguments, but each should be a two-element list:"

SyntaxInformation[f] = {"ArgumentsPattern" -> {{_, _} ...}};

{f[{x, y}, {a, b}], f[x, {a, b}, {x, y, z}]};

In the first part of the example: 'f[{x, y}, {a, b}]', '{x, y}' is a
two-elements list, so is '{a, b}'; then syntax constrain holds and it is
understandable for me.

In the second part of the example: 'f[x, {a, b}, {x, y, z}]', 'x' evaluates
to a list but not necessarily to a two-elements list. According to the
scarce explanation given in the example, it is not excluded for 'x' to
evaluate to a 12-elements list '{x, y}', however the syntax constrain allows
it to pass; following with the example the list '{a, b}' is again a
two-elements list, so it pass the check. But finally '{x, y, z}' is a
three-elements list but it is allowed to pass the constrain too; and so do
{v, x, y, z}, and {u, v, x, y, z}, and any list of whatever any other length
as this {f[{x, y}, {a, b}], f[x, {a, b}, Array[100, x]]}.

In the example

Options[f]={aaa->1,bbb->2,ccc -> 4};

SyntaxInformation[f]={"ArgumentsPattern"->{_,_,OptionsPattern[]}};

the syntax specification allows for two parameters and a list of options to
be submitted to the function 'f[]'. But it does no seem to work as expected
since the following is allowed to pass (and it seems Ok since just two
parameters and a list of options are submitted)

f[x,y, aaa->2,bbb->3,ccc ->4];

but the following is allowed to pass too, despite, in this case, 6
parameters (plus the options) are submitted instead of just the two
parameters specified in the SyntaxInformation[f] definition

f[x, y, z, k, l, m, aaa->2,bbb->3,ccc->4];

I am certainly missing something important here and, clearly, I do not
understand the explanation given for this very basic command. So I would
appreciate any clarification from the Group.

Or maybe Wolfram should provide a complete tutorial on it or a clearer
explanation.

Regards

E. Martin-Serrano

From: Bill Rowe on 5 Jul 2010 21:13

On 7/5/10 at 6:02 AM, eMartinSerrano(a)telefonica.net (E.
Martin-Serrano) wrote:

>In the ref/SyntaxInformation in the Help there is the following
>example or explanation can be found:

>"f can have any number of arguments, but each should be a
>two-element list:"

>SyntaxInformation[f] = {"ArgumentsPattern" -> {{_, _} ...}};

>{f[{x, y}, {a, b}], f[x, {a, b}, {x, y, z}]};

>But finally '{x, y, z}' is a three elements list but it is allowed to
>pass the constrain too; and so do {v, x, y, z}, and {u, v, x, y, z},

No, not true. When you look at the documentation page for
SyntaxInformation, actually execute the cell containing:

SyntaxInformation[f] = {"ArgumentsPattern" -> {{_, _} ...}};

and note the color for z changes from blue to red (assuming
default syntax coloring) indicating a syntax error. And further
if you paste any of the above examples into the documentation
notebook you will find all of the elements of the last list past
the first two are colored red.

>and any list of whatever any other length as this {f[{x, y}, {a, b}],
>f[x, {a, b}, Sequence@@Array[x&, 100]]}.

In this last example, you have an expression being given as an
argument. There is no way for Mathematica to show an syntax
error until that expression is evaluated. So, simply typing it
in cannot cause an indication of a syntax error.

>In the example

>Options[f]={aaa->1,bbb->2,ccc -> 4};
>SyntaxInformation[f]={"ArgumentsPattern"->{_,_,OptionsPattern[]}};

>The syntax specification allows for two parameters and a list of
>options to be submitted to the function =91f[]=92.

>The following does work as expected since the following is allowed
>to pass it is right since just two parameters and a list of options
>are submitted as specified)

>f[x,y, aaa->2,bbb->3,ccc ->4];

>But the following is allowed to pass too, despite, in this case, 6
>parameters *x, y, z, k, l, m* (plus the options) are submitted
>instead of just the two specified parameters.

>f[x, y, z, k, l, m, aaa->2,bbb->3,ccc->4];

>When I say they pass, I mean nothing is colored red saying that
>something is syntactically wrong and must be corrected..

The additional arguments z, k, l, m could all evaluate as a
options rule. So, they are not colored red since they might be
valid syntax.

>This occurs in version 7.0.1. for Windows XP SP3.

I am using version 7.0.1 on Mac OS X version 10.6.4. But I don't
believe the difference in platform is significant.

From: E. Martin-Serrano on 7 Jul 2010 07:39

Thanks Bill,

Very useful your remarks. Mainly the one about the symbols that might
evaluate to options as in

Options[f]={aaa->1,bbb->2,ccc -> 4};

SyntaxInformation[f]={"ArgumentsPattern"->{_,_,OptionsPattern[]}};

f[x, y, z, k, l, m, aaa->2,bbb->3,ccc->4].

It seems to me that SintaxInformation[] is a bit tricky to use as a syntax
oriented tool; since, at least in this respect, the form that Mathematica
treats SyntaxInformation[] involves both semantics and syntax. In the
example, "k", "l", "m" are not by any means under the form of an option rule
and if the parser were able to color separately the hypothetically offending
elements (due to semantics) one could decide whether these elements are
meant to evaluate to options or not.

That is why your remark has been usefull. By keeping the focus in the form,
I had hardly ever thought "k", "l", "m" were being taken as potential
options.

Besides, IMO in the case of

f[x, {a, b}, Sequence@@Array[x&, 100]], the parser should be able to know
that Sequence@@Array[x&, 100] is just a sequence of 100 elements which
clearly breaks the syntaz specification.

In other words perhaps SintaxInformation[] should distinguish between sintax
violation indications and semantic warnings.

Thanks again.

Emilio.

-----Original Message-----
From: Bill Rowe [mailto:readnews(a)sbcglobal.net]
Sent: Tuesday, July 06, 2010 3:14 AM
Subject: Re: SyntaxInformation Question

On 7/5/10 at 6:02 AM, eMartinSerrano(a)telefonica.net (E.
Martin-Serrano) wrote:

>In the ref/SyntaxInformation in the Help there is the following
>example or explanation can be found:

>"f can have any number of arguments, but each should be a
>two-element list:"

>SyntaxInformation[f] = {"ArgumentsPattern" -> {{_, _} ...}};

>{f[{x, y}, {a, b}], f[x, {a, b}, {x, y, z}]};

>But finally '{x, y, z}' is a three elements list but it is allowed to
>pass the constrain too; and so do {v, x, y, z}, and {u, v, x, y, z},

No, not true. When you look at the documentation page for
SyntaxInformation, actually execute the cell containing:

SyntaxInformation[f] = {"ArgumentsPattern" -> {{_, _} ...}};

and note the color for z changes from blue to red (assuming
default syntax coloring) indicating a syntax error. And further
if you paste any of the above examples into the documentation
notebook you will find all of the elements of the last list past
the first two are colored red.

>and any list of whatever any other length as this {f[{x, y}, {a, b}],
>f[x, {a, b}, Sequence@@Array[x&, 100]]}.

In this last example, you have an expression being given as an
argument. There is no way for Mathematica to show an syntax
error until that expression is evaluated. So, simply typing it
in cannot cause an indication of a syntax error.

>In the example

>Options[f]={aaa->1,bbb->2,ccc -> 4};
>SyntaxInformation[f]={"ArgumentsPattern"->{_,_,OptionsPattern[]}};

>The syntax specification allows for two parameters and a list of
>options to be submitted to the function =91f[]=92.

>The following does work as expected since the following is allowed
>to pass it is right since just two parameters and a list of options
>are submitted as specified)

>f[x,y, aaa->2,bbb->3,ccc ->4];

>But the following is allowed to pass too, despite, in this case, 6
>parameters *x, y, z, k, l, m* (plus the options) are submitted
>instead of just the two specified parameters.

>f[x, y, z, k, l, m, aaa->2,bbb->3,ccc->4];

>When I say they pass, I mean nothing is colored red saying that
>something is syntactically wrong and must be corrected..

The additional arguments z, k, l, m could all evaluate as a
options rule. So, they are not colored red since they might be
valid syntax.

>This occurs in version 7.0.1. for Windows XP SP3.

I am using version 7.0.1 on Mac OS X version 10.6.4. But I don't
believe the difference in platform is significant.

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