LiDIA has an abstract interface to the underlying long integer implementation.
Using CLN instead of the default libI, lip or gmp has the following
advantages:

  - Maximum speed on all CPUs, since CLN is based on the highly
    optimized gmp-2.0.2.

  - Very large integers profit from CLN's Schnhage-Strassen FFT multiplication
    (asymptotic bit complexity: O(N log N log log N)).

  - Copying integers is fast: no copying is actually involved, only a
    reference count is manipulated.

  - Small integers (absolute value < 2^29) are represented immediately,
    thus no memory allocation/deallocation is involved when dealing with
    small integers.

