(maxima.info)Introduction to Expressions

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6.1 Introduction to Expressions
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There are a number of reserved words which should not be used as
variable names.  Their use would cause a possibly cryptic syntax error.

     integrate            next           from                 diff
     in                   at             limit                sum
     for                  and            elseif               then
     else                 do             or                   if
     unless               product        while                thru
     step

   Most things in Maxima are expressions.  A sequence of expressions can
be made into an expression by separating them by commas and putting
parentheses around them.  This is similar to the C comma expression.

     (%i1) x: 3$
     (%i2) (x: x+1, x: x^2);
     (%o2)                          16
     (%i3) (if (x > 17) then 2 else 4);
     (%o3)                           4
     (%i4) (if (x > 17) then x: 2 else y: 4, y+x);
     (%o4)                          20

   Even loops in Maxima are expressions, although the value they return
is the not too useful 'done'.

     (%i1) y: (x: 1, for i from 1 thru 10 do (x: x*i))$
     (%i2) y;
     (%o2)                         done

   Whereas what you really want is probably to include a third term in
the comma expression which actually gives back the value.

     (%i3) y: (x: 1, for i from 1 thru 10 do (x: x*i), x)$
     (%i4) y;
     (%o4)                        3628800