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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 [Experiment]
    Opal [Experiment]
  • Opal - Wikipedia
    The internal structure of precious opal causes it to diffract light, resulting in play-of-color Depending on the conditions in which it formed, opal may be transparent, translucent, or opaque, and the background color may be white, black, or nearly any color of the visual spectrum
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    Opal makes it easy to create multi-step flows that chain prompts, model calls, and tools together Simply type what you want to make with natural language and Opal builds a workflow you can
  • Opal - GIA
    Opal's shifting play of kaleidoscopic colors is unlike any other gem Because opal has the colors of other gems, the Romans thought it was the most precious and powerful of all The Bedouins believed that opals contained lightning and fell from the sky during thunderstorms
  • 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
  • Opal: Formation, Properties, Types Play-of-Color Explained
    Unlike crystalline gemstones such as diamond or quartz, opal forms from microscopic silica spheres arranged in delicate internal patterns As light passes through these tiny structures, it creates the famous “play-of-color” effect that made opal legendary among collectors and jewelers
  • Opal Gemstone Information: Varieties, Colors, Care, and More
    Explore comprehensive opal gemstone information covering varieties like black, fire, and boulder opals, their colors and patterns, historical significance, care tips, and symbolic meanings for enthusiasts and buyers





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