Perl source code is compiled into things called optrees. This is a linked list of things to execute and you can see some parts of this if you use the B::Concise module. Here's an example:

C:\Documents and Settings\Josh>perl -MO=Concise -e "print @ARGV"
7  <@> leave[1 ref] vKP/REFC ->(end)
1     <0> enter ->2
2     <;> nextstate(main 1 -e:1) v ->3
6     <@> print vK ->7
3        <0> pushmark s ->4
5        <1> rv2av[t2] lK/1 ->6
4           <#> gv[*ARGV] s ->5
-e syntax OK

[download]

This is actually just a bunch of C structs and perl is just walking them in order using this ultra simple runloop:

int
Perl_runops_standard(pTHX)
{
    dVAR;
    while ((PL_op = CALL_FPTR(PL_op->op_ppaddr)(aTHX))) {
        PERL_ASYNC_CHECK();
    }

    TAINT_NOT;
    return 0;
}

[download]

Since perl code is compiled into a kind of data, it's actually pretty lispy by this point. You can inspect and modify this data directly.

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In reply to Re: Perl is a compiler cum interpreter? by diotalevi
in thread Perl is a compiler cum interpreter? by Anonymous Monk

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