Should anything go wrong or you simply want to examine intermediate representations of the IDL input, a couple of options for dumping debugging information are provided:
-d or --debug
Enable the output of a little bit of debugging information on stderr.
-dshow-passes
Report on stderr what phase of the compiler is currently processing the input.
-ddump-idl
Output the (pretty printed) abstract syntax tree on stderr.
-ddump-ds
Dump a simplified, and desugared IDL representation on stderr.
-ddump-rn
Dump a desugared and renamed IDL representation on stderr. This differs from the desugared output in that IDL names have been transformed to make them unique within the Haskell modules they're about to get mapped to.
-ddump-absH
Output the abstract Haskell representation of the input on stderr.
--output-dump=file
Instead of outputting the dump on stderr, output it
to file.