— Macro: m4_for (var, first, last, [step], expression)

Loop over the numeric values between first and last including bounds by increments of step. For each iteration, expand expression with the numeric value assigned to var. If step is omitted, it defaults to ‘1’ or ‘-1’ depending on the order of the limits. If given, step has to match this order.

— Macro: m4_foreach (var, list, expression)

Loop over the comma-separated M4 list list, assigning each value to var, and expand expression. The following example outputs two lines:

          m4_foreach([myvar], [[foo], [bar, baz]],
                     [echo myvar
          ])
          
     

— Macro: m4_foreach_w (var, list, expression)

Loop over the whitespace-separated list list, assigning each value to var, and expand expression.

The deprecated macro AC_FOREACH is an alias of m4_foreach_w.