/* ==================================================================== */
/* file: macro.dem     */
/* At some point, we get the message: DISPLACE undefined */

/* First, we'll play with some macros that do stack manipulation.
   A stack behaves like a pile of physical objects. You can pile
   more things on top of it or you can examine/remove the top object.
   Classically, the operators PUSH and POP apply to stacks. Let's
   try some examples... */

/* PUSH -- Adds a value to top of a stack */

PUSH(VALUE,STACKNAME)::=BUILDQ([VALUE,STACKNAME],
		STACKNAME:CONS(VALUE,STACKNAME))$

/* POP -- Removes a value from top of a stack */

POP(STACKNAME)::=BUILDQ([STACKNAME],
			BLOCK([TEMP:FIRST(STACKNAME)],
			      STACKNAME:REST(STACKNAME),TEMP))$

A:[];
PUSH('FOO,A);
PUSH('BAR,A);
A;
POP(A);
A;
POP(A);
A;

/* Now let's write a function-defining function. Suppose we have some
   function that we feel like we are always recycling by making just a few
   minor changes and leaving most of it intact ... eg, 

	POLY1(X):=X^3+45*X^2+432*X+1
	POLY2(X):=X^3+45*X^2+432*X+2
	... etc.

   We might consider writing a macro for ourselves to save us the typing
   done by defining this new each time. eg, ...  */

POLYDEF(N)::=BUILDQ([NAME:CONCAT('POLY,N),N],
		    NAME(X):=X^3+45*X^2+432*X+N);
MEMBER('POLY83,FUNCTIONS);
POLYDEF(83);
DISPFUN(POLY83);