Hy treats the following environment variables specially. Boolean environment variables are interpreted as false when set to the empty string and true when set to anything else.
(Default: nothing) Path to a file containing Hy source code to execute when starting the REPL.
(Default: false) Whether to show some parts of tracebacks that point to internal Hy code and won’t be helpful to the typical Hy user.
~/.hy-history) Path to which REPL input history will be saved.
(Default: false) Whether to print “Compiling FILENAME” to standard error before compiling each file of Hy source code. This is helpful for debugging whether files are being loaded from bytecode or re-compiled.