Your right that a single operator is created for the entire string of commas. Your snippet doesn't prove that, but -MO=Concise does. 

>perl -MO=Concise -wle"print scalar(1,2,3,)"
Useless use of a constant in void context at -e line 1.
8  <@> leave[1 ref] vKP/REFC ->(end)
1     <0> enter ->2
2     <;> nextstate(main 1 -e:1) v ->3
7     <@> print vK ->8
3        <0> pushmark s ->4
-        <1> scalar sK/1 ->7
6           <@> list sK ->7               <-- one operator
4              <0> pushmark v ->5
-              <0> ex-const v ->-         \ 
-              <0> ex-const v ->5         |<- three operands
5              <$> const[IV 3] s ->6      /
-e syntax OK

[download]

But the list operator doesn't return a list in scalar context. No reduction occurs, default or otherwise. 

PP(pp_list)
{
    dVAR; dSP; dMARK;
    if (GIMME != G_ARRAY) {
        if (++MARK <= SP)
            *MARK = *SP;
        else
            *MARK = &PL_sv_undef;
        SP = MARK;
    }
    RETURN;
}

[download]

It's the builtin or operator that makes the choice, not the context.

In reply to Re^8: Scalar context of slice (myth) by ikegami
in thread Scalar context of slice by thenaz

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