.TH HH_CLIENT 1

.SH NAME
hh_client \- Interface to Hack language typechecker

.SH SYNOPSIS
.B hh_client
.RI [ MODE ]
.RI [ OPTIONS ]
.RI [ DIRECTORY ]

.SH DESCRIPTION

.BR hh_client (1)
is an interface to a static analysis tool which is what enforces most of the
Hack language's type system. Code must pass validation of this tool in order to
be considered valid code in the Hack language.

There are several possible
.IR MODE s
for
.BR hh_client (1)
(see below). By default, it will invoke the
.B check
mode, with the current directory as
.IR DIRECTORY .
These are reasonable defaults, meaning that most users can
simply invoke the command as

.nf
.RS
hh_client
.RE
.fi

with no arguments to get a list of type errors across the entire project.

All of the
.IR MODE s
accept a
.I DIRECTORY
as an optional final argument. This denotes the project upon which to operate.
.BR hh_client (1)
walks up the filesystem from the
.I DIRECTORY
until it finds a file called
.I .hhconfig
and then operates on the body of Hack language code rooted in this directory.
If no
.I DIRECTORY
is specified, it uses the current directory by default. This means you may run
.BR hh_client (1)
in any subdirectory of your project and get type errors for the whole project
without ever specifying a
.I DIRECTORY
explicitly.

.BR hh_client (1)
implements very little logic itself, but rather serves as an interface to the
.BR hh_server (1)
daemon. The server will automatically be started and restarted as needed.

.SH MODES

.SS check

The default
.I MODE
if none is specified. With no
.I OPTIONS
specified, it prints a list of type errors on standard output, or prints
"No errors!" if there were none.

Many
.I OPTIONS
affect the output of
.B check
mode, sometimes causing it to do completely different things. (Those can be
considered "sub-modes" of
.B check
mode.) Many of these options are undergoing considerable revision and so are not
documented here; read the source for a full list.

Widely-useful
.I OPTIONS
for
.B check
mode include:

.TP
.BI \-\-color " FILE"
Sub-mode which prints out information on what parts of
.I FILE
are actually typechecked and which are not. Due to Hack's partial mode and PHP
interoperability, the type system may not know the types of parts of a program.
In this case, it trusts the programmer and carries on. The
.B \-\-color
mode prints out a file with ANSI terminal colors, where green code is actually
fully checked, and red code cannot be fully checked due to such missing type
information.

.TP
.B \-\-help
Prints information about
.BR hh_client (1)
and its command line options, and then exits. Many of the options described
there are experimental, especially if they are not described in this man
page.

.TP
.BI \-\-from " EDITOR"
Prints output in the format expected by a specific editor. Valid values of
.I EDITOR
are
.B emacs
and
.BR vim .
For usage by other tools, try
.B \-\-json
instead.

.TP
.B \-\-json
Prints output in a JSON format intended for machine consumption, instead of the
output intended for human consumption that is output by default.

.TP
.BI \-\-retries " NUM"
If the typechecker daemon is busy, try
.I NUM
times to connect to it before giving up. Set
.I NUM
to 0 to disable retries if the server is not immediately available.

.TP
.B \-\-status
Prints human-readable type error information to standard out and then exits.
The default sub-mode of
.B check
if none is specified. This output is not intended for usage by tools, but
only for human consumption. For output intended for tool usage, see the
.B \-\-json
and/or
.B \-\-from
options.

.TP
.B \-\-version
Prints the current client version, including build ID and build date, and
then exits.

.TP
.B \-\-auto-complete
Autocompletes text on STDIN where the cursor is replaced with
.I AUTO332.
Returns a newline-separated list.

.TP
.BI \-\-search " STRING"
Fuzzy search symbol definitions for
.I STRING.
Returns a newline-separated list.

.SS start

Explicitly starts the
.BR hh_server (1)
daemon if it is not already running. This is not normally necessary, since
.B check
mode will start it as needed if it is not running.

.SS stop

Explicitly stops the
.BR hh_server (1)
daemon if it is running. This is not normally necessary, since the daemon
will exit if it has not been used for an extended period of time.

.SS restart

Explicitly stops and then starts again the
.BR hh_server (1)
daemon. Fails if the daemon is not currently running. Restarting the daemon
is not normally necessary, since it updates its state in the background, and
.BR hh_client (1)
will restart it automatically if the typechecker binaries have been updated.

.SH EXIT STATUS

For
.B check
mode in the
.B \-\-status
sub-mode,
.BR hh_client (1)
returns 0 if there are no type errors, and non-zero otherwise.

Exit statuses for any other invocations are currently undefined and subject to
change.

.SH ENVIRONMENT

.TP
.B USER
Used in combination with the path to the project root in order to locate the
socket for communicating with the running
.BR hh_server (1)
daemon. Normally set by your login environment, but may be unset in some
nonstandard setups.

.SH FILES

.TP
.I .hhconfig
When determining where the project root is in order to figure out what files to
actually typecheck,
.BR hh_client (1)
walks up the directory tree from the specified
.I DIRECTORY
until it finds this file. The set of files recursively included in the directory
with the
.I .hhconfig
file is the set of files typechecked.

.TP
.IB /tmp/hh_server_ $USER /
The client looks inside this directory for sockets to communicate with the
.BR hh_server (1)
daemon. The sockets are named based on a hash of the absolute path of the
project root.

.SH BUGS
The Hack language is part of the HHVM project. Known bugs can be found at that
tracker, and new ones should be reported there as well:
.I https://github.com/facebook/hhvm/issues

.SH SEE ALSO
.BR hh_server (1), \ hackificator (1), \ hack_remove_soft_types (1).
.br
.I http://docs.hhvm.com/hack/typechecker/setup
.br
.I http://www.hacklang.org/