Languages where numbers are lvalues

Perl5. No, really. A number is a constant lvalue in Perl. You want proof?

*PI = \3.14159265;    # Make $PI come from a constant reference
$x = \42;             # $x IS a reference to a constant scalar

       PROGRAM OOF
C
C      ALL PARAMETERS IN FORTRAN ARE PASSED BY REFERENCE!
C      DEC (5) PASSES IN A STATIC GLOBAL REFERENCE
C      TO A MEMORY AREA INITIALLY CONTAINING 5.
C      DEC DECREMENTS THE VALUE IN THAT MEMORY AREA
C
10     CALL DEC (5)
20     IF (2+2 .EQ. 5) WRITE (*, 30)
30     FORMAT ('DOSTOEVSKY, EAT YOUR HEART OUT!')
40     END

C      SUBROUTINE DEC - DECREMENT ARGUMENT BY 1
C
60     SUBROUTINE DEC (I)
70     I = I - 1
80     END