Ferret is a free software Clojure implementation, it compiles a restricted subset of the Clojure language to self contained ISO C++11 which allows for the use of Clojure in real time embedded control systems – Ferret by Nurullah Akkaya)

From its documentation

Ferret does not depend on any external dependencies (Including the C++ Standard Library). Unit tests are run on Mac OS X and Linux, any operating system with a C++11 compiler is supported. When running on a microcontroller ferret will check if it is a supported platform during compile time and enable hardware specific features. (Currently only UART is hardware specific.) If running on an unknown hardware it will run in safe mode (UART disabled.). Everything else is supported in safe mode. Like operating system support any embedded system with a C++11 compiler is supported. There's a list of currently supported microcontrollers in the Ferret documentation under Hardware / Operating System Support.