Multilingual experiments in automatic differentiation

1. Prolog plus CHR, plus tests on inside-outside algorithm Requires SWI Prolog with the add-on package ccprism (plus dependencies).

2. Python (a): using Theano to implement IO algorithm

3. Python (b): using Tensorflow to implement IO algorithm

4. Julia: implementation of IO algorithm using ReverseDiff.jl

5. OCaml: a sort of arrow based on ideas from category theory

6. Haskell: a better arrow, supporting higher order derivatives.