**************************Chez Scheme Code Generator************************** The Chez Scheme code generator is the default, or it can be accessed via a REPLcommand: ::     Main> :set cg chez By default, therefore, to run Idris programs you will need to install`Chez Scheme <https://www.scheme.com/>`_. Chez Scheme is open source, andavailable via most OS package managers. You can compile an expression ``expr`` of type ``IO ()`` to an executable asfollows, at the REPL: ::     Main> :c execname expr ...where ``execname`` is the name of the executable file. This will generatethe following: * A shell script ``build/exec/execname`` which invokes the program* A subdirectory ``build/exec/execname_app`` which contains all the data necessary  to run the program. This includes the Chez Scheme source (``execname.ss``),  the compiled Chez Scheme code (``execname.so``) and any shared libraries needed  for foreign function definitions. The executable ``execname`` is relocatable to any subdirectory, provided that``execname_app`` is also in the same subdirectory. You can also execute an expression directly: ::     Main> :exec expr Again, ``expr`` must have type ``IO ()``. This will generate a temporaryexecutable script ``_tmpchez`` in the ``build/exec`` directory, and executethat. Chez Scheme is the default code generator, so if you invoke ``idris2`` with the``-o execname`` flag, it will generate an executable script``build/exec/execname``, again with support files in ``build/exec/execname_app``.