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Sep 3, 2021
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Specify callable object closurization #1842

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4c56f28
Specify that function closurization works for callable objects
eernstg Sep 3, 2021
3c76391
Typo
eernstg Sep 3, 2021
36bfead
Fix version number
eernstg Sep 3, 2021
1e4681d
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eernstg Sep 3, 2021
e5219f4
Renamed ordinary method closurization to instance method closurizatio…
eernstg Sep 3, 2021
6d97e4a
Merge branch 'master' into specify_callable_closurization_sep21
eernstg Sep 3, 2021
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50 changes: 35 additions & 15 deletions specification/dartLangSpec.tex
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Original file line number Diff line number Diff line change
Expand Up @@ -14,7 +14,7 @@
\makeindex
\title{Dart Programming Language Specification\\
{6th edition draft}\\
{\large Version 2.13-dev}}
{\large Version 2.15-dev}}
\author{}

% For information about Location Markers (and in particular the
Expand All @@ -32,6 +32,8 @@
% - Allow generic instantiation of the `call` method of a function object.
% - Clarify that `TypeLiteral.extensionMethod()` is an error, in line with the
% error for `int.toString()`.
% - Add support for function closurization for callable objects, in the sense
% that `o` is desugared as `o.call` when the context type is a function type.
%
% 2.14
% - Add constraint on type of parameter which is covariant-by-declaration in
Expand Down Expand Up @@ -2294,7 +2296,7 @@ \subsection{Type of a Function}
function closurization
(\ref{functionClosurization})
or instance method closurization
(\ref{ordinaryMemberClosurization})
(\ref{instanceMethodClosurization})
applied to $F$,
and let $t$ be the actual type corresponding to $T$
at the occasion where $o$ was created
Expand Down Expand Up @@ -2947,7 +2949,7 @@ \subsubsection{The Method \code{noSuchMethod}}
and with the same default value for each optional parameter.
It can be invoked in an ordinary invocation and in a superinvocation,
and when $m$ is a method it can be closurized
(\ref{ordinaryMemberClosurization})
(\ref{instanceMethodClosurization})
using a property extraction
(\ref{propertyExtraction}).

Expand Down Expand Up @@ -12784,7 +12786,7 @@ \subsubsection{Function Expression Invocation}
the ordinary invocation

\noindent
\code{$e_f$.call<$A_1, \ldots,\ A_r$>($a_1, \ldots,\ a_n,\ x_{n+1}$: $a_{n+1}, \ldots,\ x_{n+k}$: $a_{n+k}$)}.
\code{$e_f$.\CALL<$A_1, \ldots,\ A_r$>($a_1, \ldots,\ a_n,\ x_{n+1}$: $a_{n+1}, \ldots,\ x_{n+k}$: $a_{n+k}$)}.

\LMHash{}%
Otherwise, the static analysis of $i$ is performed as specified
Expand Down Expand Up @@ -12879,7 +12881,7 @@ \subsection{Function Closurization}
% identical even if not required, e.g., local functions with no free variables.
\IndexCustom{Closurization}{closurization}
denotes instance method closurization
(\ref{ordinaryMemberClosurization})
(\ref{instanceMethodClosurization})
as well as function closurization,
and it is also used as a shorthand for either of them
when there is no ambiguity.
Expand Down Expand Up @@ -12928,7 +12930,7 @@ \subsection{Function Closurization}
}


\subsubsection{Generic Function Instantiation}
\subsection{Generic Function Instantiation}
\LMLabel{genericFunctionInstantiation}

%% TODO(eernst): The specification of generic function instantiation relies
Expand Down Expand Up @@ -14012,7 +14014,7 @@ \subsection{Property Extraction}
\begin{enumerate}
\item An instance method closurization,
which converts a method into a function object
(\ref{ordinaryMemberClosurization}).
(\ref{instanceMethodClosurization}).
Or
\item A getter invocation, which returns
the result of invoking of a getter method
Expand All @@ -14024,7 +14026,8 @@ \subsection{Property Extraction}
are colloquially known as tear-offs.%
}

Property extraction can be either conditional or unconditional.
\LMHash{}%
Property extraction comes in several forms, as described below.

\LMHash{}%
\Case{Conditional}
Expand Down Expand Up @@ -14106,6 +14109,24 @@ \subsection{Property Extraction}
(\ref{superGetterAccessAndMethodClosurization}).
\EndCase

\LMHash{}%
\Case{Implicit}
Let $e$ be an expression whose static type is
an interface type that has a method named \CALL.
In the case where the context type for $e$ is a function type
or the type \FUNCTION,
$e$ is treated as \code{$e$.\CALL}.

\commentary{%
This means that a ``callable object'' may be treated as a function
that supports a mechanism similar to function closurization
(\ref{functionClosurization})
by desugaring it to a method closurization on \CALL.
This only occurs when it is statically known that it is a callable object,
and when the context type requires a function.%
}
\EndCase


\subsubsection{Getter Access and Method Extraction}
\LMLabel{getterAccessAndMethodExtraction}
Expand Down Expand Up @@ -14171,7 +14192,7 @@ \subsubsection{Getter Access and Method Extraction}
\id{} in $o$ with respect to the current library $L$.
If method lookup succeeds then $i$ evaluates to
the closurization of method $f$ on object $o$
(\ref{ordinaryMemberClosurization}).
(\ref{instanceMethodClosurization}).

\commentary{%
Note that $f$ is never an abstract method,
Expand Down Expand Up @@ -14280,12 +14301,11 @@ \subsubsection{Super Getter Access and Method Closurization}
}


\subsubsection{Ordinary Member Closurization}
\LMLabel{ordinaryMemberClosurization}
\subsubsection{Instance Method Closurization}
\LMLabel{instanceMethodClosurization}

\LMHash{}%
This section specifies the dynamic semantics of
ordinary member closurizations.
This section specifies the dynamic semantics of instance method closurizations.

\commentary{%
Note that the non-generic case is covered implicitly using $s = 0$,
Expand Down Expand Up @@ -14494,7 +14514,7 @@ \subsubsection{Super Closurization}

\commentary{%
Note that a super closurization is an instance method closurization,
as defined in (\ref{ordinaryMemberClosurization}).%
as defined in (\ref{instanceMethodClosurization}).%
}

\LMHash{}%
Expand Down Expand Up @@ -14572,7 +14592,7 @@ \subsubsection{Generic Method Instantiation}
Generic method instantiation is a mechanism that yields
a non-generic function object,
based on a property extraction which denotes an instance method closurization
(\ref{ordinaryMemberClosurization}, \ref{superClosurization}).
(\ref{instanceMethodClosurization}, \ref{superClosurization}).

\commentary{%
It is a mechanism which is very similar to instance method closurization,
Expand Down