dhil
/
phd-dissertation
mirror of https://github.com/dhil/phd-dissertation
1
0
Fork 0
Code Issues Releases Wiki Activity
Browse Source

Filters

master
Daniel Hillerström 5 years ago
parent
ebca80d4b7
commit
9dcac3cf29
2 changed files with 224 additions and 7 deletions
Whitespace
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
Unified View
Diff Options
Show Stats Download Patch File Download Diff File
  1. 10
      macros.tex
  2. 221
      thesis.tex

10
macros.tex
View File

@ -365,6 +365,7 @@
\newcommand{\UFD}{\dec{FileDescr}} \newcommand{\UFD}{\dec{FileDescr}}
\newcommand{\fwrite}{\dec{fwrite}} \newcommand{\fwrite}{\dec{fwrite}}
\newcommand{\iter}{\dec{iter}} \newcommand{\iter}{\dec{iter}}
\newcommand{\map}{\dec{map}}
\newcommand{\stdout}{\dec{stdout}} \newcommand{\stdout}{\dec{stdout}}
\newcommand{\IO}{\dec{IO}} \newcommand{\IO}{\dec{IO}}
\newcommand{\BIO}{\dec{BIO}} \newcommand{\BIO}{\dec{BIO}}
@ -438,6 +439,15 @@
\newcommand{\grep}{\dec{grep}} \newcommand{\grep}{\dec{grep}}
\newcommand{\match}{\dec{match}} \newcommand{\match}{\dec{match}}
\newcommand{\wc}{\dec{wc}} \newcommand{\wc}{\dec{wc}}
\newcommand{\forever}{\dec{forever}}
\newcommand{\textnil}{\textbackslash{}0}
\newcommand{\charlit}[1]{\texttt{'#1'}}
\newcommand{\where}{\keyw{where}}
\newcommand{\intToString}{\dec{intToString}}
\newcommand{\freq}{\dec{freq}}
\newcommand{\paste}{\dec{paste}}
\newcommand{\sed}{\dec{sed}}
\newcommand{\printTable}{\dec{renderTable}}
%% %%
%% Some control operators %% Some control operators

221
thesis.tex
View File

@ -7150,13 +7150,29 @@ If the producer performs the $\Yield$ operation, then $\Pipe$ is
invoked with the resumption of the producer along with a thunk that invoked with the resumption of the producer along with a thunk that
applies the consumer's resumption to the yielded value. applies the consumer's resumption to the yielded value.
% %
For aesthetics, we define an infix alias for pipe:
For aesthetics, we define a right-associative infix alias for pipe:
$p \mid c \defas \Pipe\,\Record{p;c}$. $p \mid c \defas \Pipe\,\Record{p;c}$.
Let us put the pipe operator to use by performing a simple string
frequency analysis on a file. We will implement the analysis as a
collection of small single-purpose utilities which we connect by way
of pipes. We will build a collection of small utilities. We will make
use of two standard list iteration functions.
% %
\[ \[
\iter : \Record{\alpha \to \beta; \List~\alpha} \to \UnitType
\ba{@{~}l@{~}c@{~}l}
\map &:& \Record{\alpha \to \beta;\List~\alpha} \to \List~\beta\\
\iter &:& \Record{\alpha \to \beta; \List~\alpha} \to \UnitType
\ea
\] \]
% %
The function $\map$ applies its function argument to each element of
the provided list in left-to-right order and returns the resulting
list. The function $\iter$ is simply $\map$ where the resulting list
is ignored. Our first utility is a simplified version of the GNU
coreutil utility \emph{cat}, which copies the contents of files to
standard out~\cite[Section~3.1]{MacKenzieMPPBYS20}. Our version will
open a single file and stream its contents one character at a time.
% %
\[ \[
\bl \bl
@ -7169,7 +7185,7 @@ $p \mid c \defas \Pipe\,\Record{p;c}$.
\Some~ino &\mapsto& \bl \Case\;\Do\;\URead~ino~\{\\ \Some~ino &\mapsto& \bl \Case\;\Do\;\URead~ino~\{\\
~\ba[t]{@{~}l@{~}c@{~}l} ~\ba[t]{@{~}l@{~}c@{~}l}
\None &\mapsto& \exit\,1\\ \None &\mapsto& \exit\,1\\
\Some~cs &\mapsto& \iter\,\Record{\lambda c.\Do\;\Yield~c;cs} \}\}
\Some~cs &\mapsto& \iter\,\Record{\lambda c.\Do\;\Yield~c;cs}; \Do\;\Yield~\charlit{\textnil} \}\}
\ea \ea
\el \el
\ea \ea
@ -7177,18 +7193,209 @@ $p \mid c \defas \Pipe\,\Record{p;c}$.
\el \el
\] \]
% %
This is an example of inversion of control.
The last line is the interesting line of code. The contents of the
file gets bound to $cs$, which is supplied as an argument to the list
iteration function $\iter$. The function argument yields each
character. Each invocation of $\Yield$ effectively suspends the
iteration until the next character is awaited.
%
This is an example of inversion of control as the iterator $\iter$ has
been turned into a generator.
%
We use the character $\textnil$ to identify the end of a stream. It is
essentially a character interpretation of the empty list (file)
$\nil$.
The $\cat$ utility processes the entire contents of a given
file. However, we may only be interested in some parts. The GNU
coreutil \emph{head} provides a way to process only a fixed amount of
lines and ignore subsequent
lines~\cite[Section~5.1]{MacKenzieMPPBYS20}.
%
We will implement a simplified version of this utility which lets us
keep the first $n$ lines of a stream and discard the remainder. This
process will act as a \emph{filter}, which is an intermediary process
in a pipeline that both awaits and yields data.
%
\[
\bl
\head : \Int \to \UnitType \eff \{\Await : \UnitType \opto \Char;\Yield : \Char \opto \UnitType\}\\
\head~n \defas
\bl
\If\;n = 0\;\Then\;\Do\;\Yield~\charlit{\textnil}\\
\Else\;
\bl
\Let\;c \revto \Do\;\Await~\Unit\;\In\\
\Do\;\Yield~c;\\
\If\;c = \charlit{\textnil}\;\Then\;\Unit\\
\Else\;\If\;c = \charlit{\nl}\;\Then\;\head~(n-1)\\
\Else\;\head~n
\el
\el
\el
\]
%
The function first checks whether more lines need to be processed. If
$n$ is zero, then it yields the nil character to signify the end of
stream. This has the effect of ignoring any future instances of
$\Yield$ in the input stream. Otherwise it awaits a character. Once a
character has been received the function yields the character in order
to include it in the output stream. After the yield, it checks whether
the character was nil in which case the process
terminates. Alternatively, if the character was a newline the function
applies itself recursively with $n$ decremented by one. Otherwise it
applies itself recursively with the original $n$.
%
\[
\bl
\paste : \UnitType \to \UnitType \eff \{\Await : \UnitType \opto \Char;\Yield : \String \opto \UnitType\}\\
\paste\,\Unit \defas
\bl
paste'\,\Record{\Do\;\Await~\Unit;\strlit{}}\\
\where
\ba[t]{@{~}l@{~}c@{~}l}
paste'\,\Record{\charlit{\textnil};str} &\defas& \Do\;\Yield~str;\Do\;\Yield~\strlit{\textnil}\\
paste'\,\Record{\charlit{\nl};str} &\defas& \Do\;\Yield~str;\Do\;\Yield~\strlit{\nl};paste'\,\Record{\Do\;\Await~\Unit;\strlit{}}\\
paste'\,\Record{\charlit{~};str} &\defas& \Do\;\Yield~str;paste'\,\Record{\Do\;\Await~\Unit;\strlit{}}\\
paste'\,\Record{c;str} &\defas& paste'\,\Record{\Do\;\Await~\Unit;str \concat [c]}
\ea
\el
\el
\]
%
\[
\bl
\sed : \Record{\String;\String} \to \UnitType \eff \{\Await : \UnitType \opto \String;\Yield : \String \opto \UnitType\}\\
\sed\,\Record{target;str'} \defas
\bl
\Let\;str \revto \Do\;\Await~\Unit\;\In\\
\If\;str = target\;\Then\;\Do\;\Yield~str';\sed\,\Record{target;str'}\\
\Else\;\Do\;\Yield~str;\sed\,\Record{target;str'}
\el
\el
\]
% %
\[ \[
\bl \bl
\grep : \String \to \UnitType \eff \{\Await : \UnitType \opto \Char;\Yield : \Char \opto \UnitType\}\\
\grep~str \defas
\freq : \UnitType \to \UnitType \eff \{\Await : \UnitType \opto \String;\Yield : \List\,\Record{\String;\Int} \opto \UnitType\}\\
\freq\,\Unit \defas
\bl \bl
\match\,\Record{\Do\;\Await~\Unit; str; \nil}
freq'\,\Record{\Do\;\Await~\Unit;\nil}\\
\where
\ba[t]{@{~}l@{~}c@{~}l}
freq'\,\Record{\strlit{\textnil};tbl} &\defas& \Do\;\Yield~tbl\\
freq'\,\Record{str;tbl} &\defas&
\bl
\Let\;tbl' \revto \faild\,\Record{
\bl
\Record{str;1} \cons tbl; \lambda\Unit.\\
\Let\; sum \revto \lookup\,\Record{str;tbl}\;\In\\
\modify\,\Record{str;sum+1;tbl}}
\el\\
\In\;freq'\,\Record{\Do\;\Await~\Unit;tbl'}
\el
\ea
\el \el
\el \el
\] \]
% %
\[
\bl
\intToString : \Int \to \String
\el
\]
%
\[
\bl
\printTable : \UnitType \to \UnitType \eff \{\Await : \UnitType \opto \List\,\Record{\String;\Int}\}\\
\printTable\,\Unit \defas
\dec{map}\,\Record{\lambda\Record{s;i}.s \concat \strlit{:} \concat \intToString~i \concat \strlit{;};\Do\;\Await~\Unit}
\el
\]
%
% \[
% \bl
% \wc : \UnitType \to \UnitType \eff \{\Await : \UnitType \opto \Char;\Yield : \Int \opto \UnitType\}\\
% \wc\,\Unit \defas
% \bl
% \Do\;\Yield~(wc'\,\Unit)\\
% \where~
% \bl
% wc' \Unit \defas
% \bl
% \Let\;c \revto \Do\;\Await~\Unit\;\In\\
% \If\;c = \charlit{\textnil}\;\Then\;0\\
% \Else\; 1 + wc'~\Unit
% \el
% \el
% \el
% \el
% \]
%
\[
\ba{@{~}l@{~}l}
&\bl
\runState\,\Record{\dec{fs}_0;\fileIO\,(\lambda\Unit.\\
\quad\timeshare\,(\lambda\Unit.\\
\qquad\dec{interruptWrite}\,(\lambda\Unit.\\
\qquad\quad\sessionmgr\,\Record{\Root;\lambda\Unit.\\
\qquad\qquad\status\,(\lambda\Unit.
\ba[t]{@{}l}
\quoteHamlet~\redirect~\strlit{hamlet};\\
\Let\;cs \revto
\bl
(\lambda\Unit.\cat~\strlit{hamlet}) \mid (\lambda\Unit.\head~2) \mid \paste\\
\mid (\lambda\Unit.\sed\,\Record{\strlit{be,};\strlit{live}}) \mid (\lambda\Unit.\sed\,\Record{\strlit{To};\strlit{to}})\\
\mid \freq \mid \printTable
\el\\
\In\;(\lambda\Unit.\echo~cs)~\redirect~\strlit{analysis})})))}
\ea
\el \smallskip\\
\reducesto^+&
\bl
\Record{
\ba[t]{@{}l}
[0];\\
\Record{
\ba[t]{@{}l}
dir=[\Record{\strlit{analysis};2},\Record{\strlit{hamlet};1},
\Record{\strlit{stdout};0}];\\
ilist=[\Record{2;\Record{lno=1;loc=2}},
\Record{1;\Record{lno=1;loc=1}},
\Record{0;\Record{lno=1;loc=0}}];\\
dreg=[
\ba[t]{@{}l}
\Record{2;
\ba[t]{@{}l@{}l}
\texttt{"}&\texttt{to:2;live:2;or:1;not:1;\nl:2;that:1;is:1}\\
&\texttt{the:1;question::1;"}},
\ea\\
\Record{1;
\ba[t]{@{}l@{}l}
\texttt{"}&\texttt{To be, or not to be,\nl{}that is the question:\nl{}}\\
&\texttt{Whether 'tis nobler in the mind to suffer\nl{}"}},
\ea\\
\Record{0; \strlit{}}]; lnext=3; inext=3}}\\
\ea
\ea
\ea\\
: \Record{\List~\Int; \FileSystem}
\el
\ea
\]
%
%
% \[
% \bl
% \grep : \String \to \UnitType \eff \{\Await : \UnitType \opto \Char;\Yield : \Char \opto \UnitType\}\\
% \grep~str \defas
% \bl
% \match\,\Record{\Do\;\Await~\Unit; str; \nil}
% \el
% \el
% \]
%
\section{Parameterised handlers} \section{Parameterised handlers}
\label{sec:unary-parameterised-handlers} \label{sec:unary-parameterised-handlers}

Write Preview
Loading…
Cancel
Save