issue 13 : add functions into README.md
issue #13 : update specifications in example/* to use new syntax
issue #13 : implement string interpolation; refactor codes in domain.ml{i,} for evaluating the functions
issue #13 : update test-cases to use new syntax; add patrick test-cases; add expression use-cases
issue #13 : fix modules apt & brew
issue #13 : fix modules apt & brew
fix error message "... is not exist" => "... is not found"
issue #13 : set version 0.7.x to 0.8.0