procedure main()
bases := [5,5.]
numbers := [0,2,2.,-1,3]
every  write("expon(",b := !bases,", ",x := !numbers,")=",(expon(b,x) | "failed") \ 1)
end

procedure expon(base,power)
local op,res

base := numeric(base)            | runerror(102,base)
power := power = integer(power)  | runerr(101,power)

if power = 0 then return 1
else op := if power < 1 then
              (base := real(base)) & "/"   # force real base
              else "*"

res := 1
every 1 to abs(power) do
   res := op(res,base)
return res
end