my $x = "Foo"  . 10;

##</code><code>##

let x = "Foo" ^ int_as_string(10)

##</code><code>##

% perl -MO=Concise -e 'my $x = "Foo" . 10;'
6  <@> leave[1 ref] vKP/REFC ->(end)
1     <0> enter ->2
2     <;> nextstate(main 1 -e:1) v ->3
5     <2> sassign vKS/2 ->6
3        <$> const[PV "Foo10"] s ->4
4        <0> padsv[$x:1,2] sRM*/LVINTRO ->5
-e syntax OK