Await always awaits

docs/language/dartLangSpec.tex

 \documentclass{article}
 \usepackage{epsfig}
 \usepackage{dart}
 \usepackage{bnf}
 \usepackage{hyperref}
 \newcommand{\code}[1]{{\sf #1}}
 \title{Dart Programming Language  Specification \\
 {\large Version 1.6}}
 %\author{The Dart Team}
 \begin{document}
@@ skipping 10 matching lines @@
 \section{Scope}
 \label{ecmaScope}
 
 This Ecma standard specifies the syntax and semantics of the Dart programming language.  It does not specify the APIs of the Dart libraries except where those library elements are essential to the correct functioning of the language itself (e.g., the existence of class \cd{Object} with methods such as \cd{noSuchMethod}, \cd{runtimeType}).
 
 \section{Conformance}
 \label{ecmaConformance}
 
 A conforming  implementation of the Dart programming language must provide and support all the  APIs (libraries, types, functions, getters, setters, whether top-level, static, instance or local) mandated in this specification. 
 
-A conforming implementation is permitted to provide additional APIs, but not additional syntax, except for experimental features in support of enumerated types and deferred loading which are expected to be added in the next revision of this specification.
+A conforming implementation is permitted to provide additional APIs, but not additional syntax.
 
 % A claim of conformance with this Ecma Standard shall specify?
 
 \section{Normative References}
 \label{ecmaNormativeReferences}
 
 The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
 
 \begin{enumerate}
 \item
@@ skipping 2131 matching lines @@
 }
 \item A constant constructor invocation (\ref{const}) that is not qualified by a deferred prefix.  
 \item A constant list literal (\ref{lists}).
 \item A constant map literal (\ref{maps}).
 \item A simple or qualified identifier denoting a top-level function (\ref{functions}) or a static method (\ref{staticMethods}) that is not qualified by a deferred prefix.
 \item A parenthesized expression \code{($e$)} where $e$ is a constant expression.
 \item An expression of the form \code{identical($e_1$, $e_2$)} where $e_1$ and $e_2$ are constant expressions  and \code{identical()} is statically bound to the predefined dart function   \code{identical()} discussed above (\ref{objectIdentity}).
 \item An expression of one of the forms  \code{$e_1$ == $e_2$} or  \code{$e_1$ != $e_2$} where $e_1$ and $e_2$ are constant expressions that evaluate to a numeric, string or boolean value or to \NULL{}.
 \item An expression of one of the forms \code{!$e$}, \code{$e_1$ \&\& $e_2$} or \code{$e_1 || e_2$}, where  $e$, $e_1$ and $e_2$ are constant expressions that evaluate to a boolean value.
 \item An expression of one of the forms \~{}$e$, $e_1$ \^{} $e_2$, \code{$e_1$ \& $e_2$}, $e_1 | e_2$, $e_1 >> e_2$ or $e_1 <<  e_2$, where  $e$, $e_1$ and $e_2$ are constant expressions that evaluate to an integer value  or to \NULL{}.
-\item An expression of one of the forms \code{$-e$},  \code{$e_1 + e_2$}, \code{$e_1$ - $e_2$}, \code{$e_1$ * $e_2$}, \code{$e_1$ / $e_2$,} \code{$e_1$ \~{}/ $e_2$},  \code{$e_1  >  e_2$}, \code{$e_1  <  e_2$}, \code{$e_1$ $>$= $e_2$}, \code{$e_1$ $<$= $e_2$} or \code{$e_1$ \% $e_2$},  where $e$, $e_1$ and $e_2$ are constant expressions that evaluate to a numeric value  or to \NULL{}.
-\item An expression of the form \code{$e_1$?$e_2$:$e3$} where where $e_1$, $e_2$ and $e_3$ are constant expressions and $e_1$ evaluates to a boolean value.
+\item An expression of the form \code{$e_1 + e_2$} where $e_1$ and $e_2$ are constant expressions that evaluate to a numeric or string value or to \NULL{}.
+\item An expression of one of the forms \code{$-e$}, \code{$e_1$ - $e_2$}, \code{$e_1$ * $e_2$}, \code{$e_1$ / $e_2$,} \code{$e_1$ \~{}/ $e_2$},  \code{$e_1  >  e_2$}, \code{$e_1  <  e_2$}, \code{$e_1$ $>$= $e_2$}, \code{$e_1$ $<$= $e_2$} or \code{$e_1$ \% $e_2$},  where $e$, $e_1$ and $e_2$ are constant expressions that evaluate to a numeric value  or to \NULL{}.
+\item An expression of the form \code{$e_1$?$e_2$:$e3$} where $e_1$, $e_2$ and $e_3$ are constant expressions and $e_1$ evaluates to a boolean value.
+\item An expression of the form \code{$e$.length} where $e$ is a constant expression that evaluates to a string value.
 \end{itemize}
 
 % null in all the expressions
 
 % designed so constants do not depend on check diode being on or not.
 
 It is a compile-time error if an expression is required to be a constant expression but its evaluation  would raise an exception. 
 
 % so, checked mode? analyzers? editor/development compilers?
 \commentary{
@@ skipping 1838 matching lines @@
 An {\em await expression} allows code to yield control until an asynchronous operation (\ref{functions}) completes. 
 
  \begin{grammar}
 {\bf awaitExpression:}
       \AWAIT{} unaryExpression
  \end{grammar}
 
 Evaluation of an await expression $a$ of the form \AWAIT{} $e$ proceeds as follows:
 First, the expression $e$ is evaluated. Next:
 
-If $e$ evaluates to an instance of \code{Future}, $f$, then execution of the function $m$ immediately enclosing $a$ is suspended until after $f$ completes. The stream associated with the innermost enclosing asynchronous for loop (\ref{asynchronousFor-in}), if any, is paused. At some time after $f$ is completed, control returns to the current invocation. The stream associated with the innermost enclosing asynchronous for loop  (\ref{asynchronousFor-in}), if any, is resumed. If $f$ has completed with an exception $x$, $a$ raises $x$. If $f$ completes with a value $v$, $a$ evaluates to $v$.
+If $e$ raises an exception $x$, then an instance $f$ of class \code{Future} is allocated and later completed with $x$. Otherwise, if $e$ evaluates to an object $o$ that is not an instance of \code{Future}, then let $f$ be the result of calling \code{Future.value()} with $o$ as its argument; otherwise let $f$ be the result of evaluating $e$. 
 
-Otherwise, the value of $a$ is the value of $e$. If evaluation of $e$ raises an exception $x$, $a$ raises $x$.
+Next,  execution of the function $m$ immediately enclosing $a$ is suspended until after $f$ completes. The stream associated with the innermost enclosing asynchronous for loop (\ref{asynchronousFor-in}), if any, is paused. At some time after $f$ is completed, control returns to the current invocation. The stream associated with the innermost enclosing asynchronous for loop  (\ref{asynchronousFor-in}), if any, is resumed. If $f$ has completed with an exception $x$, $a$ raises $x$. If $f$ completes with a value $v$, $a$ evaluates to $v$.
+
+%Otherwise, the value of $a$ is the value of $e$. If evaluation of $e$ raises an exception $x$, $a$ raises $x$.
 
 \commentary{
 It is a compile-time error if  the function  immediately enclosing  $a$  is not declared asynchronous.  However, this error is simply a syntax error, because in the context of a normal function, \AWAIT{} has no special meaning.
 }
 
 \rationale{
 An await expression has no meaning in a synchronous function. If such a function were to suspend waiting for a future, it would no longer be synchronous.
 }
 
 \commentary{
@@ skipping 2368 matching lines @@
 \item The names of compile time constant variables never use lower case letters. If they consist of multiple words, those words are separated by underscores. Examples: PI,  I\_AM\_A\_CONSTANT.
 \item The names of functions (including getters, setters, methods and local or library functions) and non-constant variables begin with a lowercase letter. If the name consists of multiple words, each  word (except the first) begins with an uppercase letter.  No other uppercase letters are used. Examples: camlCase, dart4TheWorld
 \item The names of types (including classes and type aliases) begin with an upper case letter.  If the name consists of multiple words, each  word  begins with an uppercase letter.  No other uppercase letters are used. Examples: CamlCase, Dart4TheWorld.
 \item The names of type variables are short (preferably single letter). Examples: T, S, K, V , E.
 \item The names of libraries or library prefixes never use upper case letters. If they consist of multiple words, those words are separated by underscores. Example: my\_favorite\_library.
 \end{itemize}
 }
 
 
 \end{document}