<tool> A dyslexic acronym for "A Yacc-like Haskell Parser
	generator".

	An {LALR1 grammar} {parser generator} for {Haskell}.  Happy is
	written in Haskell, uses a parser generated by itself, and can
	be compiled using {ghc}, {hbc} or {gofer}.  Happy uses an
	implementation of {monadic IO} built on top of stream IO, but
	this should change when the {Haskell 1.3} {standard} has been
	implemented.

	Version: 0.9 (1996-02-28).

	Happy is covered by the {General Public License}.

	{Home (http://www.dcs.gla.ac.uk/fp/software/happy.html)}.

	{(ftp://ftp.dcs.gla.ac.uk/pub/haskell/happy/)}.

	E-mail: <andy@dcs.gla.ac.uk>, <simonm@dcs.gla.ac.uk>.

	(1996-03-21)

<hardware> To press and release a {button} on a {mouse} or
	other {pointing device}.  This generates an {event}, also
	specifying the screen position, which is processed by the
	{window manager} or {application program}.  On a mouse with
	more than one button, the unqualified term usually implies
	pressing the left-most button (with the right index finger),
	other buttons would be qualified, e.g. "{right-click}".
	{Keyboard} modifiers may also be used, e.g. "shift-click",
	meaning to hold down the shift key on the keyboard while
	clicking the mouse button.

	If the mouse moves while the button is pressed then this is a
	{drag}.

	(1995-03-14)

1. <file system> {hard link} or {symbolic link}.

	2. <hypertext> {hyperlink}.

	(1997-10-22)

<programming> To process a {node} while {traversing} a
	{graph}.

	(2001-09-30)

1. One of a small number of high-speed memory locations in a
	computer's {CPU}.  Registers differ from ordinary
	{random access memory} in several respects:

	There are only a small number of registers (the "register
	set"), typically 32 in a modern processor though some,
	e.g. {SPARC}, have as many as 144.  A register may be directly
	addressed with a few bits.  In contrast, there are usually
	millions of words of main memory (RAM), requiring at least
	twenty bits to specify a memory location.  Main memory
	locations are often specified indirectly, using an {indirect
	addressing} mode where the actual memory address is held in a
	register.

	Registers are fast; typically, two registers can be read and a
	third written -- all in a single cycle.  Memory is slower; a
	single access can require several cycles.

	The limited size and high speed of the register set makes it
	one of the critical resources in most computer architectures.
	{Register allocation}, typically one phase of the {back-end},
	controls the use of registers by a compiled program.

	See also {accumulator}, {FUBAR}, {orthogonal}, {register
	dancing}, {register allocation}, {register spilling}.

	2. An addressable location in a {memory-mapped} peripheral
	device.  E.g. the transmit data register in a {UART}.

<data> A data structure holding many values, possibly of
	different types, which is usually accessed sequentially,
	working from the head to the end of the tail - an "ordered
	list".  This contrasts with a (one-dimensional) {array}, any
	element of which can be accessed equally quickly.

	Lists are often stored using a cell and pointer arrangement
	where each value is stored in a cell along with an associated
	pointer to the next cell.  A special pointer, e.g. zero, marks
	the end of the list.  This is known as a (singly) "linked
	list".  A doubly linked list has pointers from each cell to
	both next and previous cells.

	An unordered list is a {set}.

	(1998-11-12)

1. <programming> A common name for the {integer} data type.
	In {C} for example, it means a (signed) integer of the
	computer's native {word length}.

	2. <networking> The {top-level domain} for international
	organisations.

	(1999-01-26)

1. <database> See {data dictionary}.

	2. <programming> The core of a {CASE} tool, typically a {DBMS}
	where all development documents are stored.

	(1999-04-27)

1. <programming> To put something onto a {stack} or {pdl}.

	Opposite: "{pop}".

	2. <communications> {push media}.

	[{Jargon File}]

	(1997-04-10)

<database> A collection of {records} in a {relational database}.

	(1997-06-04)

A group G is a non-empty {set} upon which a {binary} operator
	* is defined with the following properties for all a,b,c in G:

	  Closure:     G is closed under *,  a*b in G
	  Associative: * is associative on G, (a*b)*c = a*(b*c)
	  Identity:    There is an identity element  e  such that
		       a*e = e*a = a.
	  Inverse:     Every element has a unique inverse a' such that
		       a * a' = a' * a = e.  The inverse is usually
		       written with a superscript -1.

	(1998-10-03)

<jargon> 1. A piece of {hardware} that encapsulates some
	function but can't be used without some kind of {front end}.
	Today we have, especially, "{print engine}": the guts of a
	{laser printer}.

	2. An analogous piece of software; notionally, one that does a
	lot of noisy {crunching}, such as a "database engine", or
	"{search engine}".

	The hackish senses of "engine" are actually close to its
	original, pre-Industrial-Revolution sense of a skill, clever
	device, or instrument (the word is cognate to "ingenuity").
	This sense had not been completely eclipsed by the modern
	connotation of power-transducing machinery in {Charles
	Babbage}'s time, which explains why he named the
	stored-program computer that he designed in 1844 the
	"{Analytical Engine}".

	[{Jargon File}]

	(1996-05-31)

<programming> A special value used in several languages to
	represent the thing referred to by an uninitialised pointer.

	<database> A special value that may be stored in some database
	columns to represent an unknown, missing, not applicable, or
	undefined value.  Nulls are treated completely differently
	from ordinary values when evaluating SQL expressions and there
	are several SQL constructs for dealing with nulls.

	(2003-06-17)

<storage> (Or "memory") A device into which data can be
	entered, in which they can be held, and from which they can be
	retrieved at a later time.

	(1995-12-24)