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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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  • 14 Different Types Of Opal And What They All Look Like - Rock Chasing
    Opal is a fascinating mineral known for its unique play of colors and diversity There are many types of opal, each with distinct characteristics that make them special For example, boulder opal, hyalite, and fire opal are all unique forms of this mineral
  • Pictures of Opal - Black, Fire, Boulder, Blue and Pink
    Opal is one of the world's most popular gemstones and the birthstone for the month of October A nice precious opal can flash every color of the spectrum with an intensity and quality of color that surpasses the fire of diamond The best opals command prices per carat that rival expensive diamonds, rubies, sapphires, and emeralds
  • Opal Stone: Meanings, Properties and Uses - The Complete Guide
    Opal is a mineraloid or crystalline form of silica It is colorless when pure The Precious forms of Opal occur in a wide variety of colors, including white, yellow, red, orange, green, black, and blue Raw stones have a waxy, dull luster that polishes to a vibrant shine
  • Opal Gemstone | Opal Stone - GIA
    Opal is an October birthstone Grids of silica spheres 0 2 microns in size create red play-of-color flashes Opal contains up to 20% water trapped in its silica structure The novel “ Anne of Geierstein ” gave opal a reputation of being unlucky
  • 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 : Properties, Formation, Uses and Deposits » Geology Science
    Opals are a unique and mesmerizing gemstone known for their distinctive play of color, making them one of the most sought-after and mysterious gemstones in the world In this introduction, we will provide a definition and a brief overview of opals
  • Opal Gemstone: History, Properties, Types, and Care
    Explore the enchanting world of opal, a gemstone known for its mesmerizing play-of-color and unique beauty Learn about its formation, properties, famous finds, types of opal, and how to care for this delicate gem in our comprehensive guide
  • Discovering the Magic of Opal: Meaning, Uses Benefits - CrystalStones. com
    What Is Opal? Opal is the stone of the dreamer, inspiring those around it with flashes of crystalline color that seem to originate sharply from its depths Believed to hold many healing qualities and emotional comfort, opal brings a warmth of spirit that resonates like no other precious gemstone
  • Opal Gemstones: History, Symbolism, Meanings More - Opal Auctions
    Opal is a mineraloid composed of silica and water Most opals you’ll come across are 6-10% water Stable opals can have as low as 3% water content and as high as 21% Under a microscope, opal contains stacks of hydrated silica spheres aligned together like a Buckyball cube
  • A Complete Guide To Opals - nakassi. com
    Opals have long enchanted gem enthusiasts with their ethereal play of color and mystique Revered for centuries and steeped in rich symbolism, opals are among the most unique and desirable gemstones in the world





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