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S-expression

In computing, s-expressions, sexprs or sexps are a notation for nested list data, invented for and popularized by the programming language Lisp, which uses them for source code as well as data. In the usual parenthesized syntax of Lisp, an s-expression is classically defined as an atom, or an expression of the form where x and y are s-expressions; the second, recursive part of the definition represents an ordered pair, which means that s-expressions are binary trees. The definition of an atom varies per context. Most modern sexpr notations in addition use an abbreviated notation to represent lists in s-expressions, so that stands for where NIL is the special end-of-list object. In the Lisp family of programming languages, s-expressions are used to represent both source code and data. Other uses of S-expressions are in Lisp-derived languages such as DSSSL, as mark-up in communications protocols like IMAP and John McCarthy's CBCL. It's used as text representation of WebAssembly; the details of the syntax and supported data types vary in the different languages, but the most common feature among these languages is the use of S-expressions and prefix notation.

There are many variants of the S-expression format, supporting a variety of different syntaxes for different datatypes. The most supported are: Lists and pairs: Symbols: with-hyphen?@!$ a\ symbol\ with\ spaces Strings: "Hello, world!" Integers: -9876543210 Floating-point numbers: -0.0 6.28318 6.023e23The character # is used to prefix extensions to the syntax, e.g. #x10 for hexadecimal integers, or #\C for characters. When representing source code in Lisp, the first element of an S-expression is an operator or function name and any remaining elements are treated as arguments; this is called "prefix notation" or "Polish notation". As an example, the Boolean expression written 4 == in C, is represented as in Lisp's s-expr-based prefix notation; as noted above, the precise definition of "atom" varies across LISP-like languages. A quoted string can contain anything but a quote, while an unquoted identifier atom can contain anything but quotes, whitespace characters, brackets, braces and semicolons.

In either case, a prohibited character can be included by escaping it with a preceding backslash. Unicode support varies; the recursive case of the s-expr definition is traditionally implemented using cons cells. S-expressions were intended only for data to be manipulated by M-expressions, but the first implementation of Lisp was an interpreter of S-expression encodings of M-expressions, Lisp programmers soon became accustomed to using S-expressions for both code and data; this means. Nested lists can be written as S-expressions: is a two-element S-expression whose elements are two-element S-expressions; the whitespace-separated notation used in Lisp is typical. Line breaks qualify as separators; this is a simple context-free grammar for a tiny subset of English written as an s-expression, where S=sentence, NP=Noun Phrase, VP=Verb Phrase, V=Verb: Program code can be written in S-expressions using prefix notation. Example in Common Lisp: S-expressions can be read in Lisp using the function READ.

READ returns Lisp data. The function PRINT can be used to output an s-expression; the output can be read with the function READ, when all printed data objects have a readable representation. Lisp has readable representations for numbers, symbols and many other data types. Program code can be formatted as pretty printed S-expressions using the function PPRINT. Lisp programs are valid s-expressions. Is a valid s-expression, but not a valid Lisp program, since Lisp uses prefix notation and a floating point number is not valid as an operation. An S-expression preceded by a single quotation mark, as in'x, is syntactic sugar for a quoted S-expression, in this case. S-Expressions are compared to XML, a key difference being that S-Expressions are far simpler in syntax, therefore being much easier to parse. Standards for some Lisp-derived programming languages include a specification for their S-expression syntax; these include Common Lisp, ISLISP. In May 1997, Ron Rivest submitted an Internet-Draft to be considered for publication as an RFC.

The draft defined a syntax based on Lisp S-expressions but intended for general-purpose data storage and exchange rather than for programming. It was never approved as an RFC, but it has since been cited and used by other RFCs and several other publications, it was intended for use in SPKI. Rivest's format defines an S-expression as being either an octet-string or a finite list of other S-expressions, it describes three interchange formats for expressing this structure. One is the "adva

Embassy of Indonesia, Amman

The Embassy of the Republic of Indonesia in Amman is the diplomatic mission of the Republic of Indonesia to the Hashemite Kingdom of Jordan. The embassy is concurrently accredited to the State of Palestine; the first Indonesian ambassador to Jordan was Zainul Yasni. The current ambassador, Andy Rachmianto, was appointed by President Joko Widodo on 13 March 2017. Diplomatic relations between Indonesia and Jordan were established in 1950. However, the Indonesian embassy in Amman was only opened in 1985. Bilateral relations between Indonesia and Palestine were established on 19 October 1989; the embassy has been accredited to Palestine since 1 June 2004. Prior to this, Palestine was accredited to the Indonesian embassy in Tunisia. Indonesia–Jordan relations Indonesia–Palestine relations List of diplomatic missions of Indonesia

Parallax Propeller

The Parallax P8X32A Propeller is a multi-core processor parallel computer architecture microcontroller chip with eight 32-bit reduced instruction set computer central processing unit cores. Introduced in 2006, it is sold by Parallax, Inc.. The Propeller microcontroller, Propeller assembly language, Spin interpreter were designed by Parallax's cofounder and president, Chip Gracey; the Spin programming language and Propeller Tool integrated development environment were designed by Chip Gracey and Parallax's software engineer Jeff Martin. On August 6, 2014, Parallax Inc. released all of the Propeller 1 P8X32A hardware and tools as open-source hardware and software under the GNU General Public License 3.0. This included the Verilog code, top-level hardware description language files, Spin interpreter, PropellerIDE and SimpleIDE programming tools and compilers; each of the eight 32-bit cores has a central processing unit which has access to 512 32-bit long words of instructions and data. Self-modifying code is possible and is used internally, for example, as the boot loader overwrites itself with the Spin Interpreter.

Subroutines in Spin use a call-return mechanism requiring use of a call stack. Assembly code needs no call stack. Access to shared memory is controlled via round-robin scheduling by an internal computer bus controller termed the hub; each cog has access to two dedicated hardware counters and a special video generator for use in generating timing signals for Phase Alternating Line, National Television System Committee, Video Graphics Array, servomechanism-control, others. The Propeller can be clocked using either an internal, on-chip oscillator or an external crystal oscillator or ceramic resonator. Only the external oscillator may be run through an on-chip phase-locked loop clock multiplier, which may be set at 1x, 2x, 4x, 8x, or 16x. Both the on-board oscillator frequency and the PLL multiplier value may be changed at run-time. If used this can improve power efficiency. However, the utility of this technique is limited to situations where no other cog is executing timing-dependent code, since the effective clock rate is common to all cogs.

The effective clock rate ranges from 32 kHz up to 80 MHz. When running at 80 MHz, the proprietary interpreted Spin programming language executes 80,000 instruction-tokens per second on each core, giving 8 times 80,000 for 640,000 high-level instructions per second. Most machine-language instructions take 4 clock-cycles to execute, resulting in 20 million instructions per second per cog, or 160 MIPS total for an 8-cog Propeller. Power use can be reduced by lowering the clock rate to what is needed, by turning off unneeded cogs, by reconfiguring I/O pins which are unneeded, or can be safely placed in a high-impedance state, as inputs. Pins can be reconfigured dynamically, but again, the change applies to all cogs, so synchronizing is important for certain designs; some protection is available for situations where one core attempts to use a pin as an output while another attempts to use it as an input. Each cog has access to some dedicated counter-timer hardware, a special timing signal generator intended to simplify the design of video output stages, such as composite PAL or NTSC displays and Video Graphics Array monitors.

Parallax thus makes sample code available which can generate video signals using a minimum parts count consisting of the Propeller, a crystal oscillator, a few resistors to form a crude digital-to-analog converter. The frequency of the oscillator is important, as the correction ability of the video timing hardware is limited to the clock rate, it is possible to use multiple cogs in parallel to generate a single video signal. More the timing hardware can be used to implement various pulse-width modulation timing signals. In addition to the Spin interpreter and a boot loader, the built-in ROM provides some data which may be useful for certain sound, video, or mathematics applications: a bitmap font is provided, suitable for typical character generation applications; the math extensions are intended to help compensate for the lack of a floating-point unit, more primitive missing operations, such as multiplication and division. The Propeller is a 32-bit processor and these tables may have insufficient accuracy for higher-precision uses.

Spin is a multitasking high-level computer programming language created by Parallax's Chip Gracey, who designed the Propeller microcontroller on which it runs, for their line of Propeller microcontrollers. Spin code is written on the Propeller Tool, a GUI-oriented software development pl

Maxwell McCombs

Maxwell E. McCombs is an American journalism scholar known for his work on political communication, he is the Jesse H. Jones Centennial Chair in Communication Emeritus at the University of Texas at Austin, he is known for developing the agenda setting theory of mass media with Donald Lewis Shaw. In a 1972 paper, McCombs and Shaw described the results of a study they conducted testing the hypothesis that the news media have a large influence on the issues that the American public considers important, they conducted the study while they were both working at the University of North Carolina at Chapel Hill. The resulting paper, "The Agenda-Setting Function of Mass Media", has since been described as "a classic and the most cited article in the field of mass communication research in the past 35 years." McCombs has been described as, along with Shaw, "one of the two founding fathers of empirical research on the agenda-setting function of the press." McCombs and Shaw were jointly awarded the 2011 Helen Dinerman Award of the World Association for Public Opinion Research.

In 2014, McCombs received the Silver Medal from the University of Navarra in Spain, where he has been a visiting professor since 1994. With Shaw, he has received the Murray Edelman Award from the American Political Science Association. Trigueros, Joaquín. "Colloquy with Maxwell McCombs at the University of Texas at Austin: agenda setting, a limitless theory in a connected world". Church and Culture. 3: 53–74. Doi:10.1080/23753234.2018.1430513. ISSN 2375-3234

Robert Warzycha

Robert Warzycha is a Polish former professional association football player. Warzycha had a long career in Europe, playing for teams in Poland and England with Everton in the Premier League, he won a Polish Super Cup with Górnik Zabrze. Warzycha was a regular member of the Poland national football team throughout the late 1980s and early 1990s, amassing 47 caps, he moved to the United States in 1996 and subsequently spent seven seasons in Major League Soccer with Columbus Crew. He served as a coach for the team, serving as head coach for five seasons. After beginning his career in his native Poland, Warzycha moved to England in March 1991 when Howard Kendall signed him for Everton in a £500,000 deal, he started well, scoring twice in his first eight games for Everton, missing just five league games in the 1991-92. He was one of only thirteen players not from the British Isles to play on the opening weekend of the FA Premier League along with Jan Stejskal, Peter Schmeichel, Andrei Kanchelskis, Roland Nilsson, Eric Cantona, Hans Segers, John Jensen, Anders Limpar, Gunnar Halle, Craig Forrest, Michel Vonk and Ronnie Rosenthal and was the first player from mainland Europe to score in the Premier League.

His goal was the only one scored by a Polish player in the competition until Marcin Wasilewski scored in January 2015, 22 years later. His goal against Manchester United in a 3-0 win at Old Trafford proved to be his last goal for Everton, he fell out of favour that season and played just seven times in the 1993-94 season, was not part of new manager Mike Walker's plans. He went to Hungary at the end of the season to sign for Pécsi Mecsek. A year he was sold to Kispest Honvéd FC of Hungary. In 1996, he joined Columbus Crew for the Major League Soccer's inaugural year. Warzycha became a staple in the lineup for five seasons, a bit player in his final two, as he battled injuries, he retired as the Crew's all-time assist leader with 61 and scored 19 goals in MLS league play. During his playing days in Columbus, Warzycha was known as "The Polish Rifle," in part because of his accuracy from free kicks. On 25 March 2000 Warzycha scored the first-ever regular-season "Golden Goal" in Major League Soccer history to defeat the San Jose Earthquakes 2-1.

He played two more years for Columbus Crew before retiring from playing in 2002 at the age of 39. For Poland, Warzycha was capped 47 times, scoring seven goals between 1987 and 1993. After retiring as a player, he became an assistant coach with the Crew. After Greg Andrulis was fired in July 2005, Warzycha assumed interim head coaching duty, he went back to assisting. After spending several years as Schmid's assistant, Warzycha was promoted to the head coach position at Columbus Crew for the 2009 MLS season, in which he coached the team to the Supporter Shield, awarded for the most points during the regular season. Warzycha signed a multi-year contract extension with Columbus on 1 September 2011 that kept him under contract through the 2013 season, he was released from his contract early, on 2 September 2013. Robert is the father of professional soccer player Konrad Warzycha, who played for Columbus Crew under his father. Lamar Hunt U. S. Open Cup: 2002 MLS Cup: 2008 MLS Supporters Shield: 2004, 2008, 2009 Ekstraklasa: 1987, 1988 Polish SuperCup: 1988 Hungarian Cup: 1996

Field hockey at the 2020 Summer Olympics

Field hockey at the 2020 Summer Olympics in Tokyo will take place from 25 July to 7 August at the Oi Seaside Park. Twenty-four teams will compete in the tournament; each of the Continental Champions from five confederations received an automatic berth. Japan as the host nation qualified automatically. In addition, the remaining six nations were to be determined by an olympic qualification event; as Japan emerged as Asian champion in both men's and women's events, a seventh berth was made available in each qualification event. ^A – Japan qualified both as the hosts and the continental champions, therefore that quota is added to the FIH Olympic Qualifiers rather than going to the runners-up of the tournament. ^1 – Japan qualified both as the hosts and the continental champions, therefore that quota is added to the FIH Olympic Qualifiers rather than going to the runners-up of the tournament. The competition consisted of two stages. Teams were divided into two groups of six nations. Three points were awarded for one for a draw.

The top four teams per group qualified for the quarter-finals. The competition consisted of two stages. Teams were divided into two groups of six nations. Three points were awarded for one for a draw; the top four teams per group qualified for the quarter-finals. Field hockey at the 2018 Asian Games Field hockey at the 2019 Pan American Games