Haskell:

Write a function complex_decode string (using recursion) that takes a non-simple repeated encoded string, and returns the original un-encoded string.

The encoded strings may contain more than nine repeats , eg. "a11b11", so that single characters will be encoded without a number. For example "hello" encodes to "hel2o".

You can assume that the un-encoded strings are entirely formed from non-numeric characters.

You may use the library functions mod, div, length, head, and tail. All other functions should be implemented by you.