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\( % cbs-katex.sty % \newcommand{\STYLE}[2]{\htmlClass{cbs-#1}{#2}} \newcommand{\DECL}[3]{\htmlId{#1:#2}{#3}} \newcommand{\REF}[3]{\href{###1:#2}{#3}} \newcommand{\HYPER}[5]{\href{#1/#2/index.html###3:#4}{#5}} % \SHADE{MATH} can be defined to produce a shaded background to highlight % inline MATH in running text: \newcommand{\SHADE}[1]{#1} % \KEY{TEXT}, \STRING{TEXT}, \ATOM{TEXT}, \LEX{TEXT} can be used in math mode: \newcommand{\KEY}[1]{\textsf{\textit{\STYLE{Key}{#1}}}} \newcommand{\STRING}[1]{\textsf{``\texttt{#1}''}} \newcommand{\ATOM}[1]{\textsf{`\texttt{#1}'}} \newcommand{\LEX}[1]{\textsf{\STYLE{Key}{`}\texttt{#1}\STYLE{Key}{'}}} % The following commands produce ASCII characters that are treated specially by LaTeX: \newcommand{\HASH}{\char`\#} \newcommand{\DOLLAR}{\char`\$} \newcommand{\PERCENT}{\char`\%} \newcommand{\AMPERSAND}{\char`\&} \newcommand{\APOSTROPHE}{\char`\'} \newcommand{\BACKSLASH}{\char`\\} \newcommand{\CARET}{\char`\^} \newcommand{\UNDERSCORE}{\char`\_} \newcommand{\GRAVE}{\char`\`} \newcommand{\LEFTBRACE}{\char`\{} \newcommand{\RIGHTBRACE}{\char`\}} \newcommand{\TILDE}{\textasciitilde} % {\char`\~} % \NAME{name} highlights the name; % \NAMEDECL{name} declares Name.name as the target of links to name; % \NAMEREF{name} links name to the target Name.name in the current file; % \NAMEHYPER{url}{file}{name} links name to Name.name at url/file/file.pdf. % Similarly for \VAR{partvariable}, \SYN{syntaxname}, \SEM{semanticsName}, % and \SECT{sectionnumber} % The kerns in \SUB and \VAR avoid overlaps with primes: \newcommand{\SUB}[1]{_{\kern-2mu\STYLE{PartVariable}{\textsf{#1}}}} % PLAIN \newcommand{\VAR}[1]{\STYLE{PartVariable}{\textsf{\textit{#1}\kern2mu}}} \newcommand{\NAME}[1]{\STYLE{Name}{\textsf{#1}}} \newcommand{\SYN}[1]{\STYLE{SyntaxName}{\textsf{#1}}} \newcommand{\SEM}[1]{\STYLE{SemanticsName}{\textsf{#1}}} \newcommand{\SECT}[1]{\STYLE{SectionNumber}{\textsf{#1}}} % DECL \newcommand{\VARDECL}[1]{\DECL{PartVariable}{#1}{\VAR{#1}}} \newcommand{\NAMEDECL}[1]{\DECL{Name}{#1}{\NAME{#1}}} \newcommand{\SYNDECL}[1]{\DECL{SyntaxName}{#1}{\SYN{#1}}} \newcommand{\SEMDECL}[1]{\DECL{SemanticsName}{#1}{\SEM{#1}}} \newcommand{\SECTDECL}[1]{\DECL{SectionNumber}{#1}{\textsf{#1}}} % REF \newcommand{\VARREF}[1]{\REF{PartVariable}{#1}{\VAR{#1}}} \newcommand{\NAMEREF}[1]{\REF{Name}{#1}{\NAME{#1}}} \newcommand{\SYNREF}[1]{\REF{SyntaxName}{#1}{\SYN{#1}}} \newcommand{\SEMREF}[1]{\REF{SemanticsName}{#1}{\SEM{#1}}} \newcommand{\SECTREF}[1]{\REF{SectionNumber}{#1}{\SECT{#1}}} % HYPER \newcommand{\VARHYPER}[3]{\HYPER{#1}{#2}{PartVariable}{#3}{\VAR{#3}}} \newcommand{\NAMEHYPER}[3]{\HYPER{#1}{#2}{Name}{#3}{\NAME{#3}}} \newcommand{\SYNHYPER}[3]{\HYPER{#1}{#2}{SyntaxName}{#3}{\SYN{#3}}} \newcommand{\SEMHYPER}[3]{\HYPER{#1}{#2}{SemanticsName}{#3}{\SEM{#3}}} \newcommand{\SECTHYPER}[3]{\HYPER{#1}{#2}{SectionNumber}{#3}{\SECT{#3}}} % \LEFTPHRASE MATH \RIGHTPHRASE produces [[ MATH ]] with proper brackets: \newcommand{\LEFTPHRASE}{\llbracket} \newcommand{\RIGHTPHRASE}{\rrbracket} % \LEFTGROUP MATH \RIGHTGROUP produces ( MATH ) where the parentheses are % highlighted the same as keywords: \newcommand{\LEFTGROUP}{\STYLE{Key}{(}} \newcommand{\RIGHTGROUP}{\STYLE{Key}{)}} % MATH\PLUS produces a superscript + % MATH\STAR produces a superscript * % MATH\QUERY produces a superscript ? \newcommand{\PLUS}{{}^{\texttt{+}}} \newcommand{\STAR}{{}^{\texttt{*}}} \newcommand{\QUERY}{{}^{\texttt{?}}} % \RULE{& PREMISE \\ & ...}{& FORMULA ... \\ & ...} produces an inference rule % with separately aligned premises and conclusion % PREMISE % ... % ----------- % FORMULA ... % ... \newcommand{\RULE}[2] {\frac{\begin{aligned}#1\end{aligned}}{\begin{aligned}#2\end{aligned}}} % \AXIOM{& FORMULA ... \\ & ...} produces an aligned formula % % FORMULA ... % ... \newcommand{\AXIOM}[1]{\begin{aligned}#1\end{aligned}} % \TO TYPE produces => TYPE \newcommand{\TO}{\mathop{\Rightarrow}} % TERM \TRANS TERM produces TERM ---> TERM \newcommand{\TRANS}{\longrightarrow} % TERM \xrightarrow{LABEL} TERM puts the label above the long arrow % \)

Unstable-Languages-beta : SIMPLE-THR-3-Statements.cbs | PLAIN | PDF


\[\KEY{Language} \quad \STRING{SIMPLE-THR}\]

\(\SECT{3}\) Statements

\[\begin{align*} \KEY{Syntax} \quad \VARDECL{Block} : \SYNDECL{block} \ ::= \ & \ \LEX{{\LEFTBRACE}} \ \SYNREF{stmts}\QUERY \ \LEX{{\RIGHTBRACE}} \\ \VARDECL{Stmts} : \SYNDECL{stmts} \ ::= \ & \ \SYNREF{stmt} \ \SYNREF{stmts}\QUERY \\ \VARDECL{Stmt} : \SYNDECL{stmt} \ ::= \ & \ \SYNREF{imp-stmt} \mid \SYNHYPER{../.}{SIMPLE-THR-4-Declarations}{vars-decl} \\ \VARDECL{ImpStmt} : \SYNDECL{imp-stmt} \ ::= \ & \ \SYNREF{block} \\ \ \mid \ & \ \SYNHYPER{../.}{SIMPLE-THR-2-Expressions}{exp} \ \LEX{{;}} \\ \ \mid \ & \ \LEX{if} \ \LEX{{(}} \ \SYNHYPER{../.}{SIMPLE-THR-2-Expressions}{exp} \ \LEX{{)}} \ \SYNREF{block} \ \LEFTGROUP \LEX{else} \ \SYNREF{block} \RIGHTGROUP\QUERY \\ \ \mid \ & \ \LEX{while} \ \LEX{{(}} \ \SYNHYPER{../.}{SIMPLE-THR-2-Expressions}{exp} \ \LEX{{)}} \ \SYNREF{block} \\ \ \mid \ & \ \LEX{for} \ \LEX{{(}} \ \SYNREF{stmt} \ \SYNHYPER{../.}{SIMPLE-THR-2-Expressions}{exp} \ \LEX{{;}} \ \SYNHYPER{../.}{SIMPLE-THR-2-Expressions}{exp} \ \LEX{{)}} \ \SYNREF{block} \\ \ \mid \ & \ \LEX{print} \ \LEX{{(}} \ \SYNHYPER{../.}{SIMPLE-THR-2-Expressions}{exps} \ \LEX{{)}} \ \LEX{{;}} \\ \ \mid \ & \ \LEX{return} \ \SYNHYPER{../.}{SIMPLE-THR-2-Expressions}{exp}\QUERY \ \LEX{{;}} \\ \ \mid \ & \ \LEX{try} \ \SYNREF{block} \ \LEX{catch} \ \LEX{{(}} \ \SYNHYPER{../.}{SIMPLE-THR-1-Lexical}{id} \ \LEX{{)}} \ \SYNREF{block} \\ \ \mid \ & \ \LEX{throw} \ \SYNHYPER{../.}{SIMPLE-THR-2-Expressions}{exp} \ \LEX{{;}} \\ \ \mid \ & \ \LEX{join} \ \SYNHYPER{../.}{SIMPLE-THR-2-Expressions}{exp} \ \LEX{{;}} \\ \ \mid \ & \ \LEX{acquire} \ \SYNHYPER{../.}{SIMPLE-THR-2-Expressions}{exp} \ \LEX{{;}} \\ \ \mid \ & \ \LEX{release} \ \SYNHYPER{../.}{SIMPLE-THR-2-Expressions}{exp} \ \LEX{{;}} \\ \ \mid \ & \ \LEX{rendezvous} \ \SYNHYPER{../.}{SIMPLE-THR-2-Expressions}{exp} \ \LEX{{;}} \end{align*}\] \[\begin{align*} \KEY{Rule} \quad & \LEFTPHRASE \ \LEX{if} \ \LEX{{(}} \ \VARHYPER{../.}{SIMPLE-THR-2-Expressions}{Exp} \ \LEX{{)}} \ \VARREF{Block} \ \RIGHTPHRASE : \SYNREF{stmt} = \\& \LEFTPHRASE \ \LEX{if} \ \LEX{{(}} \ \VAR{Exp} \ \LEX{{)}} \ \VAR{Block} \ \LEX{else} \ \LEX{{\LEFTBRACE}} \ \LEX{{\RIGHTBRACE}} \ \RIGHTPHRASE \\ \KEY{Rule} \quad & \LEFTPHRASE \ \LEX{for} \ \LEX{{(}} \ \VARREF{Stmt} \ \VARHYPER{../.}{SIMPLE-THR-2-Expressions}{Exp}\SUB{1} \ \LEX{{;}} \ \VARHYPER{../.}{SIMPLE-THR-2-Expressions}{Exp}\SUB{2} \ \LEX{{)}} \\&\quad \LEX{{\LEFTBRACE}} \ \VARREF{Stmts} \ \LEX{{\RIGHTBRACE}} \ \RIGHTPHRASE : \SYNREF{stmt} = \\& \LEFTPHRASE \ \LEX{{\LEFTBRACE}} \ \VAR{Stmt} \\&\quad \LEX{while} \ \LEX{{(}} \ \VAR{Exp}\SUB{1} \ \LEX{{)}} \\&\quad \LEX{{\LEFTBRACE}} \ \LEX{{\LEFTBRACE}} \ \VAR{Stmts} \ \LEX{{\RIGHTBRACE}} \ \VAR{Exp}\SUB{2} \ \LEX{{;}} \ \LEX{{\RIGHTBRACE}} \\&\quad \LEX{{\RIGHTBRACE}} \ \RIGHTPHRASE \end{align*}\] \[\begin{align*} \KEY{Semantics} \quad & \SEMDECL{exec} \LEFTPHRASE \ \_ : \SYNREF{stmts} \ \RIGHTPHRASE : \TO \NAMEHYPER{../../../../../Funcons-beta/Values/Primitive}{Null}{null-type} \\ \KEY{Rule} \quad & \SEMREF{exec} \LEFTPHRASE \ \LEX{{\LEFTBRACE}} \ \LEX{{\RIGHTBRACE}} \ \RIGHTPHRASE = \NAMEHYPER{../../../../../Funcons-beta/Values/Primitive}{Null}{null} \\ \KEY{Rule} \quad & \SEMREF{exec} \LEFTPHRASE \ \LEX{{\LEFTBRACE}} \ \VARREF{Stmts} \ \LEX{{\RIGHTBRACE}} \ \RIGHTPHRASE = \SEMREF{exec} \LEFTPHRASE \ \VAR{Stmts} \ \RIGHTPHRASE \\ \KEY{Rule} \quad & \SEMREF{exec} \LEFTPHRASE \ \VARREF{ImpStmt} \ \VARREF{Stmts} \ \RIGHTPHRASE = \\&\quad \NAMEHYPER{../../../../../Funcons-beta/Computations/Normal}{Flowing}{sequential} ( \SEMREF{exec} \LEFTPHRASE \ \VAR{ImpStmt} \ \RIGHTPHRASE , \SEMREF{exec} \LEFTPHRASE \ \VAR{Stmts} \ \RIGHTPHRASE ) \\ \KEY{Rule} \quad & \SEMREF{exec} \LEFTPHRASE \ \VARHYPER{../.}{SIMPLE-THR-4-Declarations}{VarsDecl} \ \VARREF{Stmts} \ \RIGHTPHRASE = \\&\quad \NAMEHYPER{../../../../../Funcons-beta/Computations/Normal}{Binding}{scope} ( \SEMHYPER{../.}{SIMPLE-THR-4-Declarations}{declare} \LEFTPHRASE \ \VAR{VarsDecl} \ \RIGHTPHRASE , \SEMREF{exec} \LEFTPHRASE \ \VAR{Stmts} \ \RIGHTPHRASE ) \\ \KEY{Rule} \quad & \SEMREF{exec} \LEFTPHRASE \ \VARHYPER{../.}{SIMPLE-THR-4-Declarations}{VarsDecl} \ \RIGHTPHRASE = \NAMEHYPER{../../../../../Funcons-beta/Computations/Normal}{Flowing}{effect} ( \SEMHYPER{../.}{SIMPLE-THR-4-Declarations}{declare} \LEFTPHRASE \ \VAR{VarsDecl} \ \RIGHTPHRASE ) \\ \KEY{Rule} \quad & \SEMREF{exec} \LEFTPHRASE \ \VARHYPER{../.}{SIMPLE-THR-2-Expressions}{Exp} \ \LEX{{;}} \ \RIGHTPHRASE = \NAMEHYPER{../../../../../Funcons-beta/Computations/Normal}{Flowing}{effect} ( \SEMHYPER{../.}{SIMPLE-THR-2-Expressions}{rval} \LEFTPHRASE \ \VAR{Exp} \ \RIGHTPHRASE ) \\ \KEY{Rule} \quad & \SEMREF{exec} \LEFTPHRASE \ \LEX{if} \ \LEX{{(}} \ \VARHYPER{../.}{SIMPLE-THR-2-Expressions}{Exp} \ \LEX{{)}} \ \VARREF{Block}\SUB{1} \ \LEX{else} \ \VARREF{Block}\SUB{2} \ \RIGHTPHRASE = \\&\quad \NAMEHYPER{../../../../../Funcons-beta/Computations/Normal}{Flowing}{if-else} ( \SEMHYPER{../.}{SIMPLE-THR-2-Expressions}{rval} \LEFTPHRASE \ \VAR{Exp} \ \RIGHTPHRASE , \SEMREF{exec} \LEFTPHRASE \ \VAR{Block}\SUB{1} \ \RIGHTPHRASE , \SEMREF{exec} \LEFTPHRASE \ \VAR{Block}\SUB{2} \ \RIGHTPHRASE ) \\ \KEY{Rule} \quad & \SEMREF{exec} \LEFTPHRASE \ \LEX{while} \ \LEX{{(}} \ \VARHYPER{../.}{SIMPLE-THR-2-Expressions}{Exp} \ \LEX{{)}} \ \VARREF{Block} \ \RIGHTPHRASE = \NAMEHYPER{../../../../../Funcons-beta/Computations/Normal}{Flowing}{while} ( \SEMHYPER{../.}{SIMPLE-THR-2-Expressions}{rval} \LEFTPHRASE \ \VAR{Exp} \ \RIGHTPHRASE , \SEMREF{exec} \LEFTPHRASE \ \VAR{Block} \ \RIGHTPHRASE ) \\ \KEY{Rule} \quad & \SEMREF{exec} \LEFTPHRASE \ \LEX{print} \ \LEX{{(}} \ \VARHYPER{../.}{SIMPLE-THR-2-Expressions}{Exps} \ \LEX{{)}} \ \LEX{{;}} \ \RIGHTPHRASE = \NAMEHYPER{../../../../../Funcons-beta/Computations/Normal}{Interacting}{print} ( \SEMHYPER{../.}{SIMPLE-THR-2-Expressions}{rvals} \LEFTPHRASE \ \VAR{Exps} \ \RIGHTPHRASE ) \\ \KEY{Rule} \quad & \SEMREF{exec} \LEFTPHRASE \ \LEX{return} \ \VARHYPER{../.}{SIMPLE-THR-2-Expressions}{Exp} \ \LEX{{;}} \ \RIGHTPHRASE = \NAMEHYPER{../../../../../Funcons-beta/Computations/Abnormal}{Returning}{return} ( \SEMHYPER{../.}{SIMPLE-THR-2-Expressions}{rval} \LEFTPHRASE \ \VAR{Exp} \ \RIGHTPHRASE ) \\ \KEY{Rule} \quad & \SEMREF{exec} \LEFTPHRASE \ \LEX{return} \ \LEX{{;}} \ \RIGHTPHRASE = \NAMEHYPER{../../../../../Funcons-beta/Computations/Abnormal}{Returning}{return} ( \NAMEHYPER{../../../../../Funcons-beta/Values/Primitive}{Null}{null} ) \\ \KEY{Rule} \quad & \SEMREF{exec} \LEFTPHRASE \ \LEX{try} \ \VARREF{Block}\SUB{1} \ \LEX{catch} \ \LEX{{(}} \ \VARHYPER{../.}{SIMPLE-THR-1-Lexical}{Id} \ \LEX{{)}} \ \VARREF{Block}\SUB{2} \ \RIGHTPHRASE = \\&\quad \NAMEHYPER{../../../../../Funcons-beta/Computations/Abnormal}{Throwing}{handle-thrown} ( \\&\quad\quad \SEMREF{exec} \LEFTPHRASE \ \VAR{Block}\SUB{1} \ \RIGHTPHRASE , \\&\quad\quad \NAMEHYPER{../../../../../Funcons-beta/Computations/Normal}{Binding}{scope} ( \\&\quad\quad\quad \NAMEHYPER{../../../../../Funcons-beta/Computations/Normal}{Binding}{bind} ( \SEMHYPER{../.}{SIMPLE-THR-1-Lexical}{id} \LEFTPHRASE \ \VAR{Id} \ \RIGHTPHRASE , \NAMEHYPER{../../../../../Funcons-beta/Computations/Normal}{Storing}{allocate-initialised-variable} ( \NAMEHYPER{../../../../../Funcons-beta/Values}{Value-Types}{values}, \NAMEHYPER{../../../../../Funcons-beta/Computations/Normal}{Giving}{given} ) ), \\&\quad\quad\quad \SEMREF{exec} \LEFTPHRASE \ \VAR{Block}\SUB{2} \ \RIGHTPHRASE ) ) \\ \KEY{Rule} \quad & \SEMREF{exec} \LEFTPHRASE \ \LEX{throw} \ \VARHYPER{../.}{SIMPLE-THR-2-Expressions}{Exp} \ \LEX{{;}} \ \RIGHTPHRASE = \NAMEHYPER{../../../../../Funcons-beta/Computations/Abnormal}{Throwing}{throw} ( \SEMHYPER{../.}{SIMPLE-THR-2-Expressions}{rval} \LEFTPHRASE \ \VAR{Exp} \ \RIGHTPHRASE ) \end{align*}\]

SIMPLE uses natural numbers to identify threads; the use of \(\SHADE{\NAMEHYPER{../../../../../Unstable-Funcons-beta/Computations/Normal}{Indexing}{lookup-index} ( \_ )}\) below converts a natural number to the associated thread-id.

\[\begin{align*} \KEY{Rule} \quad & \SEMREF{exec} \LEFTPHRASE \ \LEX{join} \ \VARHYPER{../.}{SIMPLE-THR-2-Expressions}{Exp} \ \LEX{{;}} \ \RIGHTPHRASE = \\&\quad \NAMEHYPER{../../../../../Unstable-Funcons-beta/Computations/Threads}{Multithreading}{thread-join} \ \NAMEHYPER{../../../../../Unstable-Funcons-beta/Computations/Normal}{Indexing}{lookup-index} ( \SEMHYPER{../.}{SIMPLE-THR-2-Expressions}{rval} \LEFTPHRASE \ \VAR{Exp} \ \RIGHTPHRASE ) \end{align*}\]

The use of \(\SHADE{\NAMEHYPER{../../../../../Unstable-Funcons-beta/Computations/Normal}{Memos}{memo-value} ( \VAR{V}, \VAR{SY} )}\) below associates \(\SHADE{\VAR{V}}\) with a lock. When a thread requests a lock already held by another thread, the requesting thread is suspended until the request is granted. The use of \(\SHADE{\NAMEHYPER{../../../../../Unstable-Funcons-beta/Computations/Abnormal}{Postponing}{postpone} ( \_ )}\) below automatically releases held locks when the current thread terminates.

\[\begin{align*} \KEY{Rule} \quad & \SEMREF{exec} \LEFTPHRASE \ \LEX{acquire} \ \VARHYPER{../.}{SIMPLE-THR-2-Expressions}{Exp} \ \LEX{{;}} \ \RIGHTPHRASE = \\&\quad \NAMEHYPER{../../../../../Funcons-beta/Computations/Normal}{Giving}{give} ( \\&\quad\quad \NAMEHYPER{../../../../../Unstable-Funcons-beta/Computations/Normal}{Memos}{memo-value} ( \SEMHYPER{../.}{SIMPLE-THR-2-Expressions}{rval} \LEFTPHRASE \ \VAR{Exp} \ \RIGHTPHRASE , \NAMEHYPER{../../../../../Unstable-Funcons-beta/Computations/Threads/Synchronising}{Locks}{reentrant-lock-create} ), \\&\quad\quad \NAMEHYPER{../../../../../Funcons-beta/Computations/Normal}{Flowing}{sequential} ( \\&\quad\quad\quad \NAMEHYPER{../../../../../Unstable-Funcons-beta/Computations/Abnormal}{Postponing}{postpone} \\&\quad\quad\quad\quad \NAMEHYPER{../../../../../Funcons-beta/Computations/Normal}{Flowing}{if-true-else} ( \\&\quad\quad\quad\quad\quad \NAMEHYPER{../../../../../Unstable-Funcons-beta/Computations/Threads/Synchronising}{Locks}{is-exclusive-lock-holder} \ \NAMEHYPER{../../../../../Funcons-beta/Computations/Normal}{Giving}{given}, \\&\quad\quad\quad\quad\quad \NAMEHYPER{../../../../../Unstable-Funcons-beta/Computations/Threads/Synchronising}{Locks}{reentrant-lock-release} \ \NAMEHYPER{../../../../../Funcons-beta/Computations/Normal}{Giving}{given}, \\&\quad\quad\quad\quad\quad \NAMEHYPER{../../../../../Funcons-beta/Values/Primitive}{Null}{null-value} ), \\&\quad\quad\quad \NAMEHYPER{../../../../../Unstable-Funcons-beta/Computations/Threads/Synchronising}{Locks}{reentrant-lock-sync-else-wait} \ \NAMEHYPER{../../../../../Funcons-beta/Computations/Normal}{Giving}{given} ) ) \end{align*}\]

The use of \(\SHADE{\NAMEHYPER{../../../../../Unstable-Funcons-beta/Computations/Normal}{Memos}{memo-value-recall} ( \VAR{V} )}\) below gives the lock associated with \(\SHADE{\VAR{V}}\).

\[\begin{align*} \KEY{Rule} \quad & \SEMREF{exec} \LEFTPHRASE \ \LEX{release} \ \VARHYPER{../.}{SIMPLE-THR-2-Expressions}{Exp} \ \LEX{{;}} \ \RIGHTPHRASE = \\&\quad \NAMEHYPER{../../../../../Unstable-Funcons-beta/Computations/Threads/Synchronising}{Locks}{reentrant-lock-exit} \ \NAMEHYPER{../../../../../Unstable-Funcons-beta/Computations/Normal}{Memos}{memo-value-recall} \ \SEMHYPER{../.}{SIMPLE-THR-2-Expressions}{rval} \LEFTPHRASE \ \VAR{Exp} \ \RIGHTPHRASE \end{align*}\]

The use of \(\SHADE{\NAMEHYPER{../../../../../Unstable-Funcons-beta/Computations/Normal}{Memos}{memo-value} ( \VAR{V}, \VAR{SY} )}\) below associates \(\SHADE{\VAR{V}}\) with a rendezvous. When a thread requests a rendezvous on a particular value, and there is no previous uncompleted request for a rendezvous on the same value, the requesting thread is suspended until the request is granted.

\[\begin{align*} \KEY{Rule} \quad & \SEMREF{exec} \LEFTPHRASE \ \LEX{rendezvous} \ \VARHYPER{../.}{SIMPLE-THR-2-Expressions}{Exp} \ \LEX{{;}} \ \RIGHTPHRASE = \\&\quad \NAMEHYPER{../../../../../Unstable-Funcons-beta/Computations/Threads/Synchronising}{Notifications}{rendezvous-sync-else-wait} ( \\&\quad\quad \NAMEHYPER{../../../../../Unstable-Funcons-beta/Computations/Normal}{Memos}{memo-value} ( \STRING{rendezvous}, \NAMEHYPER{../../../../../Unstable-Funcons-beta/Computations/Threads/Synchronising}{Notifications}{rendezvous-create} ( 2 ) ), \\&\quad\quad \SEMHYPER{../.}{SIMPLE-THR-2-Expressions}{rval} \LEFTPHRASE \ \VAR{Exp} \ \RIGHTPHRASE ) \end{align*}\]