############################## librep 版 ############################## 
#!/usr/bin/rep
!#
;; 沒有下面這列 (保持註解), x 就是一個 lexical variable;
;; 加上下面這列 (把分號拿掉), x 就變成一個 dynamic variable
;(defvar x 1)

(let (
	(x -1)
    )
    (defun f (choice)
	(let (
		(x 5)
	    )
	    (defun h ()
		(format standard-output "%d\n" x)
	    )
	    (defun g1 ()
		(let (
			(x 31)
		    )
		    (h)
		)
	    )
	    (defun g2 ()
		(let (
			(x 42)
		    )
		    (h)
		)
	    )
	    (if (eq choice 1) (g1) (g2))
	)
    )

    (f 1)
    (f 2)
    (format standard-output "%d\n" x)
)

############################## perl 版 ############################## 
#!/usr/bin/perl -w
# lexical scoping 與 dynamic scoping 的比較:
# 請執行本程式, 然後把 use vars 這句, 以及三句 local 通通註解掉,
# 又把各句下面的 my 打開 (井號拿掉), 再執行一次. 比較兩次的結果.

use strict;

use vars qw($x);
#my ($x);

$x = -1;

sub f {
    local ($x) = 5;
#    my ($x) = 5;
    sub h {
	print "$x\n";
    }
    sub g1 {
	local ($x) = 31;
#	my ($x) = 31;
	h();
    }
    sub g2 {
	local ($x) = 42;
#	my ($x) = 42;
	h();
    }
    if ($_[0] == 1) {
	g1();
    } else {
	g2();
    }
}

f(1);
f(2);
print "$x\n";

############################## pascal 版 ############################## 
{
翻譯: p2c scoping.pas
編譯: gcc scoping.c -lp2c
執行: ./a.out
}
program scoping_demo;
    const
	x = -1;
    procedure f(choice: integer);
	const
	    x = 5;
	procedure h;
	begin
	    writeln(x);
	end;
	procedure g1;
	    const
		x = 31;
	begin
	    h;
	end;
	procedure g2;
	    const
		x = 42;
	begin
	    h;
	end;
    begin
	if (choice = 1) then
	    g1
	else
	    g2;
    end;
begin
    f(1);
    f(2);
    writeln(x);
end.