A few quick comments:
(1) Your function 'mino' is buggy--try (as did RJF) h(sin(x)). Among
other problems, I think the function 'op' needs protection against a
mapatom arg.
(2) Most of the 'return' statements in your code aren't needed.
(3) Try rewriting your code so that it is nicer to the global
environment --- something like (EC = environmentally correct)
g(x):=block([o,u,re,lst1 : [sin,asin,sinh,tan,atan,tanh], lst2 :
lst2:[cos,cot], inflag : true],
...
Especially, try to get rid of the global assignments var : x and x0 : 0.
(4) Twenty is a magic number in your function pr (taylor(f,var,x0,20))).
Why 20? Does 20 terms always work?
(5) Give your functions names that suggest what they do.
Regards,
Barton