happy - the parser generator for Haskell
happy [OPTION]... file [OPTION]...
This manual page documents briefly the happy command.
This manual page was written for the Debian GNU/Linux distribution
because the original program does not have a manual page. Instead, it has
documentation in various other formats, including DVI, Info and HTML; see
below.
Happy is a parser generator system for Haskell. `HAPPY' is
a dyslexic acronym for `A Yacc-like Haskell Parser generator'.
There are two types of grammar files, file.y and
file.ly, with the latter observing the reverse comment bird track
convention (i.e. each code line must begin with `>'). The examples
distributed with Happy are all of the .ly form.
Caveat: When using hbc (Chalmers Haskell) the command
argument structure is slightly different. This is because the hbc run time
system takes some flags as its own (for setting things like the heap size,
etc). This problem can be circumvented by adding a single dash (`-') to your
command line. So when using a hbc generated version of Happy, the argument
structure is:
happy - [OPTION]... file
[OPTION]...
The programs follow the usual GNU command line syntax, with long
options starting with two dashes (`--'). A summary of options is included
below. For a complete description, see the other documentation.
- -h, --help
- Show summary of options.
- -v, --version
- Print version information on standard output then exit successfully.
- -a, --array
- Instructs Happy to generate a parser using an array-based shift reduce
parser. When used in conjunction with -g, the arrays will be
encoded as strings, resulting in faster parsers. Without -g,
standard Haskell arrays will be used.
- -g, --ghc
- Instructs Happy to generate a parser that uses GHC-specific extensions to
obtain faster code.
- -c, --coerce
- Use GHC's unsafeCoerce# extension to generate smaller faster
parsers. One drawback is that some type safety is lost, which means that a
parser generated with -c may compile fine but crash at run-time. Be
sure to compile your grammar without -c first to ensure it is
type-correct.
This option has quite a significant effect on the performance
of the resulting parser, but remember that parsers generated this way
can only be compiled by GHC 3.02 and above.
This option may only be used in conjunction with
-g.
- -d, --debug
- Generate a parser that will print debugging information to stderr
at run-time, including all the shifts, reductions, state transitions and
token inputs performed by the parser.
This option may only be used in conjunction with
-a.
- -i [FILE],
--info[=FILE]
- Directs Happy to produce an info file containing detailed information
about the grammar, parser states, parser actions, and conflicts. Info
files are vital during the debugging of grammars.
The filename argument is optional, and if omitted the info
file will be written to FILE.info (where FILE is the input
file name with any extension removed).
- -o FILE,
--outfile=FILE
- Specifies the destination of the generated parser module. If omitted, the
parser will be placed in FILE.hs, where FILE is the name of
the input file with any extension removed. If FILE is - the
generated parser is sent to the standard output.
- -m NAME,
--magic-name=NAME
- Happy prefixes all the symbols it uses internally with either happy
or Happy. To use a different string, for example if the use of
happy is conflicting with one of your own functions, specify the
prefix using the -m option.
- -t DIR,
--template=DIR
- Instructs Happy to use this directory when looking for template files:
these files contain the static code that Happy includes in every generated
parser. You shouldn't need to use this option if Happy is properly
configured for your computer.
- -l,
--glr
- Instructs Happy to output a GLR parser instead of an LALR(1) parser.
- -k,
--decode
- Causes the GLR parser to generate code for decoding the parse forest to a
list of semantic results (requires --ghc).
- -f,
--filter
- Causes the GLR parser to filter out nodes which aren't required for the
semantic results (an experimental optimisation, requires --ghc).
Happy Version 1.20.0
Copyright (c) 1993-1996 Andy Gill, Simon Marlow; (c) 1997-2001
Simon Marlow
This manual page was written by Michael Weber
<michaelw@debian.org>, for the Debian GNU/Linux system (but may be
used by others).