++ed by:
CXW

1 PAUSE user

Stefan O'Rear
and 3 contributors

NAME

viv - A retargettable Perl 6 metacompiler

DESCRIPTION

viv converts code, written in a subset of Perl 6, into code in Perl 5 (and eventually several other languages). viv is not a general compiler; it makes little to no attempt to provide faithful Perl 6 semantics, so code intended to be run through viv needs to restrict itself to a "nice" subset of Perl 6. Exactly what "nice" means hasn't been completely nailed down, but multithreading, the MOP, augmenting system classes, and operator overloading are all almost certainly out.

* First, viv reads your source code (which must be encoded in UTF-8). If the --thaw option is provided, the source is expected to be in Storable format; this eliminates parsing overhead and makes viv ~7 times faster. Useful for experimenting with modifications to viv itself.

* Second, the source code is parsed into an object-oriented abstract syntax tree using STD.pm6 and STD::Actions. If --freeze is passed, the process stops here and a Storable dump is generated.

* Translation of the parse tree into output code occurs in a single interleaved pass, however it takes different paths for regex and non-regex code. Non-regex code is mostly passed through, with targetted syntax-dependant rewrites; as possible, we are changing this to generate DEEP. Regexes are converted into a narrowed REgex AST format, which is translated into DEEP and additionally dumped for post-translation processing by the LTM engine.

* The DEEP engine handles differences between output formats, taking advantage of its much narrower form.