Availability:built-in
 compilingTrue if the system is compiling source files with the -c 
option or qcompile/1 
into an intermediate code file. Can be used to perform conditional code 
optimisations in term_expansion/2 
(see also the
-O option) or to omit execution of directives during 
compilation.
compilingTrue if the system is compiling source files with the -c 
option or qcompile/1 
into an intermediate code file. Can be used to perform conditional code 
optimisations in term_expansion/2 
(see also the
-O option) or to omit execution of directives during 
compilation.