Guard against running Delete[] on an empty list.

[rocky]

No description provided.

[mmatera]

This is what happens in WMA:

In[1]:= Delete[{},0]                                                            

Out[1]= Sequence[]

In[2]:= Delete[{},1]                                                            

Delete::partw: Part {1} of {} does not exist.

Out[2]= Delete[{}, 1]

In[3]:= Delete[{},0]                                                            

Out[3]= Sequence[]

In[4]:= Delete[a,0]                                                             

Delete::partw: Part 0 of a does not exist.

Out[4]= Delete[a, 0]

[axkr]

This is what happens in WMA:

Which version do you use?

In 14. 1:

In[1]:= Delete[{},0]                                                            
 
Out[1]= Identity[]

Sequence[] is converted to Identity[].

[mmatera]

This is what happens in WMA:

Which version do you use?

I am using 12.2 and 13.2.0

In 14.1, what happens with

Delete[{1,2,3}, 0]

?

[axkr]

In 14.1, what happens with

Delete[{1,2,3}, 0]

?

Identity[1,2,3]

because

>> Sequence[1,2,3]

Identity[1, 2, 3] 

[mmatera]

In 14.1, what happens with

Delete[{1,2,3}, 0]

?

Identity[1,2,3]

because

>> Sequence[1,2,3]

Identity[1, 2, 3] 

Until 13.2.0, Identity just accepted 1 argument. Also I wonder: Is this the "FullForm"? Or just the way in which WMA 14 formats Sequence[...] ?

[axkr]

Until 13.2.0, Identity just accepted 1 argument. Also I wonder: Is this the "FullForm"? Or just the way in which WMA 14 formats Sequence[...] ?

Not sure. I think it's evaluated in the backend. A General::argx message Identity called with 0 arguments; 1 argument is expected is also printed.

[mmatera]

LGTM