To see an example look here.
To compile Eschelle you need:
cmake, make, & 1 of (clang, gcc, vsc++)
Then cd into the repository directory and run the following:
mkdir build
(cd build && cmake .. && make)
After you build Eschelle you can run it with:
./Eschelle /path/to/esch/code
Example:
./Eschelle ../Example.esch