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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
    For use in jewellery, most opal is cut and polished to form a cabochon, a convex shape that maximises the viewing angles through which an opal's play of colour can be observed "Natural" opal refers to polished stones consisting wholly of precious opal
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    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 | 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 | 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
  • 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 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 - Gemstone Facts and Information - Gemporia
    With a rainbow of hues seemingly trapped within, Opal is one of the most colourful of the gems So, let's find out more about this fascinating beauty
  • Opal Stone Meaning, Uses, Properties, Value, More
    Opal gemstones are hydrated silica crystals that form over millions of years Learn about opal details, including stone meanings and symbolism, history, pricing, and value





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