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opal    音标拼音: ['opəl]
n. 蛋白石,猫眼石

蛋白石,猫眼石

opal
n 1: a translucent mineral consisting of hydrated silica of
variable color; some varieties are used as gemstones

Opal \O"pal\, n. [L. opalus: cf. Gr. ?, Skr. upala a rock,
stone, precious stone: cf. F. opale.] (Min.)
A mineral consisting, like quartz, of silica, but inferior to
quartz in hardness and specific gravity.
[1913 Webster]

Note: The {precious opal} presents a peculiar play of colors
of delicate tints, and is highly esteemed as a gem. One
kind, with a varied play of color in a reddish ground,
is called the {harlequin opal}. The {fire opal} has
colors like the red and yellow of flame. {Common opal}
has a milky appearance. {Menilite} is a brown impure
variety, occurring in concretions at Menilmontant, near
Paris. Other varieties are {cacholong}, {girasol},
{hyalite}, and {geyserite}.
[1913 Webster]

1. A {DSP} language.

["OPAL: A High Level Language and Environment for DSP boards
on PC", J.P. Schwartz et al, Proc ICASSP-89, 1989].

2. The language of the {object-oriented database} {GemStone}.

["Making Smalltalk a Database System", G. Copeland et al, Proc
SIGMOD'84, ACM 1984, pp.316- 325].

3. A {simulation} language with provision for {stochastic
variables}. An extension of {Autostat}.

["C-E-I-R OPAL", D. Pilling, Internal Report,
C.E.I.R. Ltd. (1963)].

4. A language for compiler testing said to be used internally
by {DEC}.

5. A {functional programming} language designed at the
{Technische Universitaet Berlin} as a testbed for the
development of {functional programs}. OPAL integrates
concepts from Algebraic Specification and Functional
Programming, which favour the (formal) development of (large)
production-quality software written in a {purely functional}
style.

The core of OPAL is a {strongly typed}, {higher-order},
{strict} applicative language which belongs to the tradition
of {Hope} and {ML}. The algebraic flavour of OPAL is visible
in the syntactical appearance and in the preference of
{parameterisation} to {polymorphism}.

OPAL supports: {information hiding} - each language unit is
divided into an interface (signature) and an implementation
part; selective import; {parameterised modules}; free
constructor {views} on {sorts}, which allow pattern-based
function definitions despite quite different implementations;
full {overloading} of names; puristic scheme language with no
{built-in} data types (except {Booleans} and denotations).

OPAL and its predecessor OPAL-0 have been used for some time
at the Technische Universitaet Berlin in CS courses and for
research into optimising compilers for applicative languages.
The OPAL compiler itself is writte entirely in OPAL.

An overview is given in "OPAL: Design And Implementation of an
Algebraic Programming Language".

{(http://cs.tu-berlin.de/~opal/)}.

{(ftp://ftp.cs.tu-berlin.de/pub/local/uebb/papers/DesignImplOpal.ps.gz)}.

(1995-02-16)



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  • Opal - Wikipedia
    A Peruvian opal (also called blue opal) is a semi-opaque to opaque blue-green stone found in Peru, which is often cut to include the matrix in the more opaque stones
  • Introducing Project Opal: A New Way to Get Task-Based Work . . .
    Today we’re introducing Project Opal in Microsoft 365 Copilot – a new AI-powered capability that executes task-based work inside a secure, observable environment you control Every organization faces the challenge of repetitive, manual work – tasks that consume valuable time and take away from strategic priorities, creativity, and high-impact work Consider the time it takes to gather
  • 14 Different Types Of Opal And What They All Look Like
    Explore the vibrant world of gemstones! Learn about the different types of opal and where to find them in our comprehensive guide
  • Pictures of Opal - Black, Fire, Boulder, Blue and Pink
    Photos of opal from around the world Guidance for people who want to buy opal, see different types of opal, understand their names, learn about synthetics and imitations
  • Opal Gemstone | Opal Stone – GIA
    Opal is the product of seasonal rains that drenched dry ground in regions such as Australia’s semi-desert “Outback ” It is known for its unique display of flashing rainbow colors
  • Opal | Properties, Types Uses | Britannica
    Opal, silica mineral extensively used as a gemstone, a submicrocrystalline variety of cristobalite In ancient times opal was included among the noble gems and was ranked second only to emerald by the Romans
  • Opal Gemstone: Origins, Types, and Buying Guide | Tianyu gems
    Primarily sourced from Australia, particularly Coober Pedy and South Australia, white opal is more abundant than black opal, making it a more affordable yet equally captivating option Its value depends on the brightness and vibrancy of its play-of-color, as well as the clarity and cut of the stone
  • What Is Opal: Everything You Need to Know - Nobbier
    What Is Opal? Opal is a hydrated amorphous form of silica (SiO₂·nH₂O) containing between 3-21% water within its mineral structure Unlike crystalline gemstones that have orderly, repeating atomic structures, opals form from silica-rich solutions that flow into cracks and cavities in rock
  • Opal : Properties, Formation, Uses and Deposits » Geology Science
    Definition: Opals are a type of mineraloid, which means they lack the crystalline structure of typical minerals Instead, opals are composed of tiny spheres of silica, often arranged in a closely packed and orderly manner What sets opals apart from other gemstones is their remarkable play of color, which is a phenomenon known as “opalescence ”
  • Opal by Lennar New Homes in Valencia, CA | From the mid $600 . . .
    Opal is a collection of new single-family detached homes by Lennar coming soon to FivePoint Valencia These homes feature innovative three-story designs that maximize space and privacy, with thoughtfully planned layouts ranging from 2 to 4 bedrooms and 1,704 to 2,679 square feet





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