A comment of the form
(*#showBasis "<file>"*)
is recognized as a directive to save the current basis (i.e., environment) to
<file>
(in the same format as the -show-basis <file>
compile-time option). The <file>
is interpreted relative to the source file
in which it appears. The comment is lexed as a distinct token and is parsed as
a structure-level declaration. [Note that treating the directive as a top-level
declaration would prohibit using it inside a functor body, which would make the
feature significantly less useful in the context of the MLton compiler sources
(with its nearly fully functorial style).]
This feature is meant to facilitate auto-completion via
company-mlton
and similar
tools.