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Re: Unacceptable bug in Mathematica

  • To: mathgroup at smc.vnet.net
  • Subject: [mg93548] Re: Unacceptable bug in Mathematica
  • From: ragfield <ragfield at gmail.com>
  • Date: Thu, 13 Nov 2008 21:09:44 -0500 (EST)
  • References: <gfgqf2$dj0$1@smc.vnet.net>

On Nov 13, 3:02 am, psycho_dad <s.nesse... at gmail.com> wrote:
> The other day, a friend discovered something that may qualify as a
> major bug in Mathematica (tested in 6.0.3):
>
> SyntaxQ["Exp[]"]
>
> (notice that Exp has no argument) returns
>
> True !!!!
>
> According to the documentation:
>
> SyntaxQ["string"] returns True if the string corresponds to
> syntactically correct input for a single Mathematica expression, and
> returns False otherwise.
>
> At least for me Exp[] is not syntactically correct. I expected more
> from Mathematica...

This absolutely is valid syntax.  Valid syntax is anything that will
successfully parse into an unevaluated Mathematica expression.  Once
it is evaluated it may or may not produce a useful result, but that
does not mean it isn't syntactically valid.  Consider the following:

In[1]:= f[]

Out[1]= f[]

In[2]:= SyntaxQ["f[]"]

Out[2]= True

In[3]:= f[] := 1;

In[4]:= f[]

Out[4]= 1

In[5]:= SyntaxQ["f[]"]

Out[5]= True

In the first case the function "f" with zero arguments has no
definition, but it is still valid syntax.  I later give it a
definition and it is still valid syntax.  It would be crazy to think
SyntaxQ["f[]"] would return a different result depending on whether f
[] was defined.

-Rob


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