+\documentclass[../thesis.tex]{subfiles}
+
+\begin{document}
+
+\ifSubfilesClassLoaded{
+ \author{%
+ Mart Lubbers\\
+ \texttt{mart@cs.ru.nl}
+ \and
+ Peter Achten\\
+ \texttt{peter@cs.ru.nl}
+ }
+ \title{Clean for Haskell Programmers}
+ \date{\today}
+
+ \stopthumb{}%
+ \setcounter{chapter}{1}
+
+ \pagenumbering{arabic}
+ \maketitle
+ \tableofcontents
+}{
+ \chapter{\glsentrytext{CLEAN} for \glsentrytext{HASKELL} Programmers}%
+ \label{chp:clean_for_haskell_programmers}
+}
+
+This note is meant to give people who are familiar with the functional programming language \gls{HASKELL} a consise overview of \gls{CLEAN} language elements and how they differ from \gls{HASKELL}.
+The goal is to support the reader when reading \gls{CLEAN} code.
+Table~\ref{tbl:syn_clean_haskell} shows frequently occuring \gls{CLEAN} language elements on the left side and their \gls{HASKELL} equivalent on the right side.
+Obviously, this summary is not exhaustive.
+Some \gls{CLEAN} language elements that are not easily translatable to \gls{HASKELL} and thus do not occur in the summary follow below.
+We hope you enjoy these notes and that it aids you in reading \gls{CLEAN} programs.
+
While \gls{CLEAN} and \gls{HASKELL} were both conceived around 1987 and have similar syntax, there are some subtle differences in syntax and functionality.
-This section describes some of the history of \gls{CLEAN} and provides a crash course in \gls{CLEAN} pecularities writen for \gls{HASKELL} programmers.
+This section describes some of the history of \gls{CLEAN} and provides a crash course in \gls{CLEAN} pecularities written for \gls{HASKELL} programmers.
+It is based on the
\Gls{CLEAN}---acronym for Clean \acrlong{LEAN}~\cite{barendregt_towards_1987}---, was originally designed as a \gls{GRS} core language but quickly served as an intermediate language for other functional languages~\cite{brus_clean_1987}.
In the early days it has also been called \emph{Concurrent} \gls{CLEAN}~\cite{nocker_concurrent_1991} but these days the language has no support for this anymore.
In the past, a \emph{double-edged} fronted even existed that allowed \gls{CLEAN} to be extended with \gls{HASKELL98} syntax and vice versa, however this frontend is no longer maintained~\cite{groningen_exchanging_2010}.
This chapter therefore gives a brief syntactical and functional comparison, a complete specification of the \gls{CLEAN} language can be found in the latest language report~\cite{plasmeijer_clean_2021}.
Many of this is based on work by Achten although that was based on \gls{CLEAN} 2.1 and \gls{HASKELL98}~\cite{achten_clean_2007}.
-When \gls{HASKELL} is mentioned I actually mean \gls{GHC}'s \gls{HASKELL} and by \gls{CLEAN} I mean \gls{CLEAN} 3.1's \gls{ITASK} compiler.
+When \gls{HASKELL} is mentioned we actually mean \gls{GHC}'s \gls{HASKELL} and by \gls{CLEAN} we mean \gls{CLEAN} 3.1's \gls{ITASK} compiler.
\section{Features}
\subsection{Modules}
Uniqueness is propagated automatically in function types but must be marked manually in data types.
Examples can be seen in \cref{lst:unique_examples}.
-\begin{lstClean}[label={lst:unique_examples},caption={Examples of uniqueness annotations}]
+\begin{lstClean}[label={lst:unique_examples},caption={Examples of uniqueness annotations in \gls{CLEAN}.}]
f :: *a -> *a // f works on unique values only
f :: .a -> .a // f works on unique and non-unique values
f :: v:a u:b -> u:b, [v<=u] // f works when a is less unique than b
\subsection{Generics}
Polytypic functions~\cite{jeuring_polytypic_1996}---also known as generic or kind-indexed fuctions---are built into \gls{CLEAN}~\cite[Chp.~7.1]{plasmeijer_clean_2021}\cite{alimarine_generic_2005} whereas in \gls{HASKELL} they are implemented as a library~\cite[Chp.~6.19.1]{ghc_team_ghc_2021}.
+The implementation of generics in \gls{CLEAN} is very similar to that of Generic H$\forall$skell~\cite{hinze_generic_2003}.
%When calling a generic function, the kind must always be specified and depending on the kind, the function may require more arguments.
For example, defining a generic equality is done as in \cref{lst:generic_eq}.
\lstinputlisting[language=Clean,firstline=4,label={lst:generic_eq},caption={Generic equality function in \gls{CLEAN}.}.]{lst/generic_eq.icl}
-Metadata about the types is available using the \cleaninline{of} syntax that gives the function access to metadata records, as can be seen in \cref{lst:generic_print} showing a generic print function. This abundance of metadata allows for very complex generic functions that near the expression level of template metaprogramming\todo[inline]{crossref chapter c-code generation}.
+Metadata about the types is available using the \cleaninline{of} syntax that gives the function access to metadata records, as can be seen in \cref{lst:generic_print} showing a generic print function. This abundance of metadata allows for very complex generic functions that near the expression level of template metaprogramming\ifSubfilesClassLoaded{}{ (See \cref{chp:first-class_datatypes})}.
\lstinputlisting[language=Clean,firstline=4,label={lst:generic_print},caption={Generic print function in \gls{CLEAN}.}]{lst/generic_print.icl}
\subsection{\glsentrytext{GADT}s}
\cleaninline{True :: Bool} & \haskellinline{True :: Bool}\\
\cleaninline{toInteger 42 :: Integer} & \haskellinline{42 :: Integer}\\
\cleaninline{38.0 :: Real} & \haskellinline{38.0 :: Float -- or Double}\\
- \cleaninline{"Hello" +++ "World" :: String}\footnote{Strings are represented as unboxed character arrays.}
- & \haskellinline{"Hello" ++ "World" :: String}\footnote{Strings are represented as lists of characters by default but may be overloaded as well if \GHCmod{OverloadedStrings} is enabled.}\\
- \cleaninline{['Hello'] :: [Char]} & \haskellinline{"Hello" :: String}\\
+ \cleaninline{\"Hello\" +++ \"World\" :: String}\footnote{Strings are represented as unboxed character arrays.}
+ & \haskellinline{\"Hello\" ++ \"World\" :: String}\footnote{Strings are represented as lists of characters by default but may be overloaded as well if \GHCmod{OverloadedStrings} is enabled.}\\
+ \cleaninline{['Hello'] :: [Char]} & \haskellinline{\"Hello\" :: String}\\
\cleaninline{?t} & \haskellinline{Maybe t}\\
\cleaninline{(?None, ?Just e)} & \haskellinline{(Nothing, Just e)}\\
\cleaninline{:: T a0 ...} & \haskellinline{data T a0 ...}\\
\quad\cleaninline{= \{ f0 :: t0, ..., fn :: tn \} } & \quad\haskellinline{= T \{ f0 :: t0, ..., fn :: tn \} }\\
\cleaninline{:: T a0 ... =: t} & \haskellinline{newtype T a0 ... = t}\\
- \cleaninline{:: T = E.t Box t \& C t} & \haskellinline{data T = forall t.C t => Box t}\requiresGHCmod{ExistentialQuantification}\\
+ \cleaninline{:: T = E.t: Box t \& C t} & \haskellinline{data T = forall t.C t => Box t}\requiresGHCmod{ExistentialQuantification}\\
\midrule
\multicolumn{2}{c}{Function types}\\
\bottomrule
\end{longtable}
+\input{subfilepostamble}
+\end{document}
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