Mini-CP https://www.info.ucl.ac.be/~pschaus/minicp.html is a minimal form of constraint programming solver, designed to allow for easy experimentation and learning. 

One of the most efficient approaches to discrete optimisation solving is using lazy clause generation, which is a hybrid SAT/CP approach to solving problems.  But MiniCP does not currently support this. 

Using a version of Mini-CP written in C++ (https://ldmbouge@bitbucket.org/ldmbouge/minicpp.git), this project will build a Mini-LCG (minimal LCG solver) by combining MiniSAT http://minisat.se/ a venerable but clean SAT solver with MiniCP in C++.