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Section 2.3

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Daniel Hillerström
2021-12-17 17:57:31 +00:00
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thesis.tex
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@@ -3094,8 +3094,12 @@ The following handler implements the environment.
The handler takes as input the current $user$ and a computation that
may perform the $\Ask$ operation. When an invocation of $\Ask$ occurs
the handler pattern matches on the $user$ parameter and resumes with a
string representation of the user. With this implementation we can
interpret an application of $\whoami$.
string representation of the user. This handler is an instance of a
so-called \emph{tail-resumptive} handler~\cite{Leijen17b,XieBHSL20} as
each resumption invocation appears in tail position within in the
operation clause.
%
With this implementation we can interpret an application of $\whoami$.
%
\[
\environment~\Record{\Root;\whoami} \reducesto^+ \strlit{root} : \String
@@ -3105,8 +3109,8 @@ It is not difficult to extend this basic environment model to support
an arbitrary number of variables. This can be done by parameterising
the $\Ask$ operation by some name representation (e.g. a string),
which the environment handler can use to index into a list of string
values. In case the name is unbound the environment, the handler can
embrace the laissez-faire attitude of \UNIX{} and resume with the
values. In case the name is not bound in the environment, the handler
can embrace the laissez-faire attitude of \UNIX{} and resume with the
empty string.
\paragraph{User session management}