Re: Question on Unevaluated
- To: mathgroup at smc.vnet.net
- Subject: [mg117301] Re: Question on Unevaluated
- From: JJ <wateronwildfire at gmail.com>
- Date: Mon, 14 Mar 2011 06:01:06 -0500 (EST)
Hi,
I am not sure, but maybe the problem is that you wrote f[a;b] instead of
f[a,b] or f[{a,b}] (if it is listable).
The ";" is telling to output only f[b].
2011/3/13 Alexey <lehin.p at gmail.com>
> Hello,
>
> I am puzzled a bit by the Documentation for Unevaluated. Under "More
> information" field we read:
>
> "f[Unevaluated[expr]] effectively works by temporarily setting
> attributes so that f holds its argument unevaluated, then evaluating
> f[expr].".
>
> After reading this I expect that
>
> f[Unevaluated[1 + 1]; 2 + 1]
>
> will be returned completely unevaluated as it is when I set HoldFirst
> attribute to f:
>
> In[2]:= SetAttributes[f, HoldFirst]
> f[Unevaluated[1 + 1]; 2 + 1]
>
> Out[3]= f[Unevaluated[1 + 1]; 2 + 1]
>
> But in really we get
>
> In[1]:= f[Unevaluated[1 + 1]; 2 + 1]
>
> Out[1]= f[3]
>
> This leads me to a question: what is implied in documentation? Which
> attributes are temporarily set and to which function?
>
>