A class for creating matcher objects from patterns. A matcher object has a mismatch method that takes a character and produces a mismatch bitvector.
The pattern must have length less than or equal 63 so that all mismatches fit into the 63-bit bitvector.
A mismatch bitvector is an Int63.t, with the least significant bit represeting the 0-th bit, and the most significant bit representing the 63-rd bit. It uses a 0 to in indicate a match and a 1 to indicate a mismatch. For a pattern p_0,...,p_n and a character c, the mismatch bitvector contains a 0 in the i-th bit if p_i = c and 1 otherwise.
method mismatch : P.elem -> Optint.Int63.t