Re: Unacceptable bug in Mathematica

*To*: mathgroup at smc.vnet.net*Subject*: [mg93545] Re: [mg93509] Unacceptable bug in Mathematica*From*: Daniel Lichtblau <danl at wolfram.com>*Date*: Thu, 13 Nov 2008 21:09:12 -0500 (EST)*References*: <200811130902.EAA13922@smc.vnet.net> <491C3C16.2000805@wolfram.com> <14c5433a0811130709n6d3e3162jc896d1ca1537dd6c@mail.gmail.com>

Savas Nesseris wrote: > Dear Daniel, > you say that: > "Maybe you have in mind that Exp, being a built in "function" (that is, > a symbol with DownValues attached to it), should require an "argument". > Well and good, but that's progamming language semantics, not syntax." > > OK I accept this, however then you (Wolfram Research) should remove the > following comment from the documentation of SyntaxQ, as it is misleading: > "When SyntaxQ gives True, the string can be converted to an expression:" > > And definately, > > "Exp[]" // ToExpression > > does not give /*a valid expression*/... But in fact it does give a (syntactically) valid expression. Yes, it also gives a warning message. But that is based on semantic considerations. I should mention that a "syntactically valid expression" is, by definition, anything that Mathematica will parse. Here is a related example of something that is not syntactically valid. In[3]:= ToExpression["Exp[)"] ToExpression::sntx: Invalid syntax in or before "Exp[) ". ^ Out[3]= $Failed SyntaxQ tells us, correctly, that we should have expected that one to fail. In[4]:= SyntaxQ["Exp[)"] Out[4]= False > Cheers > > PS Thanks for clarifying this point with SyntaxQ > [...] Daniel Lichtblau Wolfram Research

**References**:**Unacceptable bug in Mathematica***From:*psycho_dad <s.nesseris@gmail.com>