doc-src/Codegen/Thy/document/Introduction.tex
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     1 %
       
     2 \begin{isabellebody}%
       
     3 \def\isabellecontext{Introduction}%
       
     4 %
       
     5 \isadelimtheory
       
     6 %
       
     7 \endisadelimtheory
       
     8 %
       
     9 \isatagtheory
       
    10 \isacommand{theory}\isamarkupfalse%
       
    11 \ Introduction\isanewline
       
    12 \isakeyword{imports}\ Setup\isanewline
       
    13 \isakeyword{begin}%
       
    14 \endisatagtheory
       
    15 {\isafoldtheory}%
       
    16 %
       
    17 \isadelimtheory
       
    18 %
       
    19 \endisadelimtheory
       
    20 %
       
    21 \isamarkupsection{Introduction%
       
    22 }
       
    23 \isamarkuptrue%
       
    24 %
       
    25 \begin{isamarkuptext}%
       
    26 This tutorial introduces the code generator facilities of \isa{Isabelle{\isaliteral{2F}{\isacharslash}}HOL}.  It allows to turn (a certain class of) HOL
       
    27   specifications into corresponding executable code in the programming
       
    28   languages \isa{SML} \cite{SML}, \isa{OCaml} \cite{OCaml},
       
    29   \isa{Haskell} \cite{haskell-revised-report} and \isa{Scala}
       
    30   \cite{scala-overview-tech-report}.
       
    31 
       
    32   To profit from this tutorial, some familiarity and experience with
       
    33   \isa{HOL} \cite{isa-tutorial} and its basic theories is assumed.%
       
    34 \end{isamarkuptext}%
       
    35 \isamarkuptrue%
       
    36 %
       
    37 \isamarkupsubsection{Code generation principle: shallow embedding \label{sec:principle}%
       
    38 }
       
    39 \isamarkuptrue%
       
    40 %
       
    41 \begin{isamarkuptext}%
       
    42 The key concept for understanding Isabelle's code generation is
       
    43   \emph{shallow embedding}: logical entities like constants, types and
       
    44   classes are identified with corresponding entities in the target
       
    45   language.  In particular, the carrier of a generated program's
       
    46   semantics are \emph{equational theorems} from the logic.  If we view
       
    47   a generated program as an implementation of a higher-order rewrite
       
    48   system, then every rewrite step performed by the program can be
       
    49   simulated in the logic, which guarantees partial correctness
       
    50   \cite{Haftmann-Nipkow:2010:code}.%
       
    51 \end{isamarkuptext}%
       
    52 \isamarkuptrue%
       
    53 %
       
    54 \isamarkupsubsection{A quick start with the Isabelle/HOL toolbox \label{sec:queue_example}%
       
    55 }
       
    56 \isamarkuptrue%
       
    57 %
       
    58 \begin{isamarkuptext}%
       
    59 In a HOL theory, the \indexdef{}{command}{datatype}\hypertarget{command.datatype}{\hyperlink{command.datatype}{\mbox{\isa{\isacommand{datatype}}}}} and \indexdef{}{command}{definition}\hypertarget{command.definition}{\hyperlink{command.definition}{\mbox{\isa{\isacommand{definition}}}}}/\indexdef{}{command}{primrec}\hypertarget{command.primrec}{\hyperlink{command.primrec}{\mbox{\isa{\isacommand{primrec}}}}}/\indexdef{}{command}{fun}\hypertarget{command.fun}{\hyperlink{command.fun}{\mbox{\isa{\isacommand{fun}}}}} declarations
       
    60   form the core of a functional programming language.  By default
       
    61   equational theorems stemming from those are used for generated code,
       
    62   therefore \qt{naive} code generation can proceed without further
       
    63   ado.
       
    64 
       
    65   For example, here a simple \qt{implementation} of amortised queues:%
       
    66 \end{isamarkuptext}%
       
    67 \isamarkuptrue%
       
    68 %
       
    69 \isadelimquote
       
    70 %
       
    71 \endisadelimquote
       
    72 %
       
    73 \isatagquote
       
    74 \isacommand{datatype}\isamarkupfalse%
       
    75 \ {\isaliteral{27}{\isacharprime}}a\ queue\ {\isaliteral{3D}{\isacharequal}}\ AQueue\ {\isaliteral{22}{\isachardoublequoteopen}}{\isaliteral{27}{\isacharprime}}a\ list{\isaliteral{22}{\isachardoublequoteclose}}\ {\isaliteral{22}{\isachardoublequoteopen}}{\isaliteral{27}{\isacharprime}}a\ list{\isaliteral{22}{\isachardoublequoteclose}}\isanewline
       
    76 \isanewline
       
    77 \isacommand{definition}\isamarkupfalse%
       
    78 \ empty\ {\isaliteral{3A}{\isacharcolon}}{\isaliteral{3A}{\isacharcolon}}\ {\isaliteral{22}{\isachardoublequoteopen}}{\isaliteral{27}{\isacharprime}}a\ queue{\isaliteral{22}{\isachardoublequoteclose}}\ \isakeyword{where}\isanewline
       
    79 \ \ {\isaliteral{22}{\isachardoublequoteopen}}empty\ {\isaliteral{3D}{\isacharequal}}\ AQueue\ {\isaliteral{5B}{\isacharbrackleft}}{\isaliteral{5D}{\isacharbrackright}}\ {\isaliteral{5B}{\isacharbrackleft}}{\isaliteral{5D}{\isacharbrackright}}{\isaliteral{22}{\isachardoublequoteclose}}\isanewline
       
    80 \isanewline
       
    81 \isacommand{primrec}\isamarkupfalse%
       
    82 \ enqueue\ {\isaliteral{3A}{\isacharcolon}}{\isaliteral{3A}{\isacharcolon}}\ {\isaliteral{22}{\isachardoublequoteopen}}{\isaliteral{27}{\isacharprime}}a\ {\isaliteral{5C3C52696768746172726F773E}{\isasymRightarrow}}\ {\isaliteral{27}{\isacharprime}}a\ queue\ {\isaliteral{5C3C52696768746172726F773E}{\isasymRightarrow}}\ {\isaliteral{27}{\isacharprime}}a\ queue{\isaliteral{22}{\isachardoublequoteclose}}\ \isakeyword{where}\isanewline
       
    83 \ \ {\isaliteral{22}{\isachardoublequoteopen}}enqueue\ x\ {\isaliteral{28}{\isacharparenleft}}AQueue\ xs\ ys{\isaliteral{29}{\isacharparenright}}\ {\isaliteral{3D}{\isacharequal}}\ AQueue\ {\isaliteral{28}{\isacharparenleft}}x\ {\isaliteral{23}{\isacharhash}}\ xs{\isaliteral{29}{\isacharparenright}}\ ys{\isaliteral{22}{\isachardoublequoteclose}}\isanewline
       
    84 \isanewline
       
    85 \isacommand{fun}\isamarkupfalse%
       
    86 \ dequeue\ {\isaliteral{3A}{\isacharcolon}}{\isaliteral{3A}{\isacharcolon}}\ {\isaliteral{22}{\isachardoublequoteopen}}{\isaliteral{27}{\isacharprime}}a\ queue\ {\isaliteral{5C3C52696768746172726F773E}{\isasymRightarrow}}\ {\isaliteral{27}{\isacharprime}}a\ option\ {\isaliteral{5C3C74696D65733E}{\isasymtimes}}\ {\isaliteral{27}{\isacharprime}}a\ queue{\isaliteral{22}{\isachardoublequoteclose}}\ \isakeyword{where}\isanewline
       
    87 \ \ \ \ {\isaliteral{22}{\isachardoublequoteopen}}dequeue\ {\isaliteral{28}{\isacharparenleft}}AQueue\ {\isaliteral{5B}{\isacharbrackleft}}{\isaliteral{5D}{\isacharbrackright}}\ {\isaliteral{5B}{\isacharbrackleft}}{\isaliteral{5D}{\isacharbrackright}}{\isaliteral{29}{\isacharparenright}}\ {\isaliteral{3D}{\isacharequal}}\ {\isaliteral{28}{\isacharparenleft}}None{\isaliteral{2C}{\isacharcomma}}\ AQueue\ {\isaliteral{5B}{\isacharbrackleft}}{\isaliteral{5D}{\isacharbrackright}}\ {\isaliteral{5B}{\isacharbrackleft}}{\isaliteral{5D}{\isacharbrackright}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{22}{\isachardoublequoteclose}}\isanewline
       
    88 \ \ {\isaliteral{7C}{\isacharbar}}\ {\isaliteral{22}{\isachardoublequoteopen}}dequeue\ {\isaliteral{28}{\isacharparenleft}}AQueue\ xs\ {\isaliteral{28}{\isacharparenleft}}y\ {\isaliteral{23}{\isacharhash}}\ ys{\isaliteral{29}{\isacharparenright}}{\isaliteral{29}{\isacharparenright}}\ {\isaliteral{3D}{\isacharequal}}\ {\isaliteral{28}{\isacharparenleft}}Some\ y{\isaliteral{2C}{\isacharcomma}}\ AQueue\ xs\ ys{\isaliteral{29}{\isacharparenright}}{\isaliteral{22}{\isachardoublequoteclose}}\isanewline
       
    89 \ \ {\isaliteral{7C}{\isacharbar}}\ {\isaliteral{22}{\isachardoublequoteopen}}dequeue\ {\isaliteral{28}{\isacharparenleft}}AQueue\ xs\ {\isaliteral{5B}{\isacharbrackleft}}{\isaliteral{5D}{\isacharbrackright}}{\isaliteral{29}{\isacharparenright}}\ {\isaliteral{3D}{\isacharequal}}\isanewline
       
    90 \ \ \ \ \ \ {\isaliteral{28}{\isacharparenleft}}case\ rev\ xs\ of\ y\ {\isaliteral{23}{\isacharhash}}\ ys\ {\isaliteral{5C3C52696768746172726F773E}{\isasymRightarrow}}\ {\isaliteral{28}{\isacharparenleft}}Some\ y{\isaliteral{2C}{\isacharcomma}}\ AQueue\ {\isaliteral{5B}{\isacharbrackleft}}{\isaliteral{5D}{\isacharbrackright}}\ ys{\isaliteral{29}{\isacharparenright}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{22}{\isachardoublequoteclose}}\ %
       
    91 \endisatagquote
       
    92 {\isafoldquote}%
       
    93 %
       
    94 \isadelimquote
       
    95 %
       
    96 \endisadelimquote
       
    97 %
       
    98 \isadeliminvisible
       
    99 %
       
   100 \endisadeliminvisible
       
   101 %
       
   102 \isataginvisible
       
   103 %
       
   104 \endisataginvisible
       
   105 {\isafoldinvisible}%
       
   106 %
       
   107 \isadeliminvisible
       
   108 %
       
   109 \endisadeliminvisible
       
   110 %
       
   111 \begin{isamarkuptext}%
       
   112 \noindent Then we can generate code e.g.~for \isa{SML} as follows:%
       
   113 \end{isamarkuptext}%
       
   114 \isamarkuptrue%
       
   115 %
       
   116 \isadelimquote
       
   117 %
       
   118 \endisadelimquote
       
   119 %
       
   120 \isatagquote
       
   121 \isacommand{export{\isaliteral{5F}{\isacharunderscore}}code}\isamarkupfalse%
       
   122 \ empty\ dequeue\ enqueue\ \isakeyword{in}\ SML\isanewline
       
   123 \ \ \isakeyword{module{\isaliteral{5F}{\isacharunderscore}}name}\ Example\ \isakeyword{file}\ {\isaliteral{22}{\isachardoublequoteopen}}examples{\isaliteral{2F}{\isacharslash}}example{\isaliteral{2E}{\isachardot}}ML{\isaliteral{22}{\isachardoublequoteclose}}%
       
   124 \endisatagquote
       
   125 {\isafoldquote}%
       
   126 %
       
   127 \isadelimquote
       
   128 %
       
   129 \endisadelimquote
       
   130 %
       
   131 \begin{isamarkuptext}%
       
   132 \noindent resulting in the following code:%
       
   133 \end{isamarkuptext}%
       
   134 \isamarkuptrue%
       
   135 %
       
   136 \isadelimquotetypewriter
       
   137 %
       
   138 \endisadelimquotetypewriter
       
   139 %
       
   140 \isatagquotetypewriter
       
   141 %
       
   142 \begin{isamarkuptext}%
       
   143 structure\ Example\ {\isaliteral{3A}{\isacharcolon}}\ sig\isanewline
       
   144 \ \ val\ fold\ {\isaliteral{3A}{\isacharcolon}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{27}{\isacharprime}}a\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ {\isaliteral{27}{\isacharprime}}b\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ {\isaliteral{27}{\isacharprime}}b{\isaliteral{29}{\isacharparenright}}\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ {\isaliteral{27}{\isacharprime}}a\ list\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ {\isaliteral{27}{\isacharprime}}b\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ {\isaliteral{27}{\isacharprime}}b\isanewline
       
   145 \ \ val\ rev\ {\isaliteral{3A}{\isacharcolon}}\ {\isaliteral{27}{\isacharprime}}a\ list\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ {\isaliteral{27}{\isacharprime}}a\ list\isanewline
       
   146 \ \ datatype\ {\isaliteral{27}{\isacharprime}}a\ queue\ {\isaliteral{3D}{\isacharequal}}\ AQueue\ of\ {\isaliteral{27}{\isacharprime}}a\ list\ {\isaliteral{2A}{\isacharasterisk}}\ {\isaliteral{27}{\isacharprime}}a\ list\isanewline
       
   147 \ \ val\ empty\ {\isaliteral{3A}{\isacharcolon}}\ {\isaliteral{27}{\isacharprime}}a\ queue\isanewline
       
   148 \ \ val\ dequeue\ {\isaliteral{3A}{\isacharcolon}}\ {\isaliteral{27}{\isacharprime}}a\ queue\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ {\isaliteral{27}{\isacharprime}}a\ option\ {\isaliteral{2A}{\isacharasterisk}}\ {\isaliteral{27}{\isacharprime}}a\ queue\isanewline
       
   149 \ \ val\ enqueue\ {\isaliteral{3A}{\isacharcolon}}\ {\isaliteral{27}{\isacharprime}}a\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ {\isaliteral{27}{\isacharprime}}a\ queue\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ {\isaliteral{27}{\isacharprime}}a\ queue\isanewline
       
   150 end\ {\isaliteral{3D}{\isacharequal}}\ struct\isanewline
       
   151 \isanewline
       
   152 fun\ fold\ f\ {\isaliteral{28}{\isacharparenleft}}x\ {\isaliteral{3A}{\isacharcolon}}{\isaliteral{3A}{\isacharcolon}}\ xs{\isaliteral{29}{\isacharparenright}}\ s\ {\isaliteral{3D}{\isacharequal}}\ fold\ f\ xs\ {\isaliteral{28}{\isacharparenleft}}f\ x\ s{\isaliteral{29}{\isacharparenright}}\isanewline
       
   153 \ \ {\isaliteral{7C}{\isacharbar}}\ fold\ f\ {\isaliteral{5B}{\isacharbrackleft}}{\isaliteral{5D}{\isacharbrackright}}\ s\ {\isaliteral{3D}{\isacharequal}}\ s{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   154 \isanewline
       
   155 fun\ rev\ xs\ {\isaliteral{3D}{\isacharequal}}\ fold\ {\isaliteral{28}{\isacharparenleft}}fn\ a\ {\isaliteral{3D}{\isacharequal}}{\isaliteral{3E}{\isachargreater}}\ fn\ b\ {\isaliteral{3D}{\isacharequal}}{\isaliteral{3E}{\isachargreater}}\ a\ {\isaliteral{3A}{\isacharcolon}}{\isaliteral{3A}{\isacharcolon}}\ b{\isaliteral{29}{\isacharparenright}}\ xs\ {\isaliteral{5B}{\isacharbrackleft}}{\isaliteral{5D}{\isacharbrackright}}{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   156 \isanewline
       
   157 datatype\ {\isaliteral{27}{\isacharprime}}a\ queue\ {\isaliteral{3D}{\isacharequal}}\ AQueue\ of\ {\isaliteral{27}{\isacharprime}}a\ list\ {\isaliteral{2A}{\isacharasterisk}}\ {\isaliteral{27}{\isacharprime}}a\ list{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   158 \isanewline
       
   159 val\ empty\ {\isaliteral{3A}{\isacharcolon}}\ {\isaliteral{27}{\isacharprime}}a\ queue\ {\isaliteral{3D}{\isacharequal}}\ AQueue\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{5B}{\isacharbrackleft}}{\isaliteral{5D}{\isacharbrackright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{5B}{\isacharbrackleft}}{\isaliteral{5D}{\isacharbrackright}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   160 \isanewline
       
   161 fun\ dequeue\ {\isaliteral{28}{\isacharparenleft}}AQueue\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{5B}{\isacharbrackleft}}{\isaliteral{5D}{\isacharbrackright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{5B}{\isacharbrackleft}}{\isaliteral{5D}{\isacharbrackright}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{29}{\isacharparenright}}\ {\isaliteral{3D}{\isacharequal}}\ {\isaliteral{28}{\isacharparenleft}}NONE{\isaliteral{2C}{\isacharcomma}}\ AQueue\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{5B}{\isacharbrackleft}}{\isaliteral{5D}{\isacharbrackright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{5B}{\isacharbrackleft}}{\isaliteral{5D}{\isacharbrackright}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{29}{\isacharparenright}}\isanewline
       
   162 \ \ {\isaliteral{7C}{\isacharbar}}\ dequeue\ {\isaliteral{28}{\isacharparenleft}}AQueue\ {\isaliteral{28}{\isacharparenleft}}xs{\isaliteral{2C}{\isacharcomma}}\ y\ {\isaliteral{3A}{\isacharcolon}}{\isaliteral{3A}{\isacharcolon}}\ ys{\isaliteral{29}{\isacharparenright}}{\isaliteral{29}{\isacharparenright}}\ {\isaliteral{3D}{\isacharequal}}\ {\isaliteral{28}{\isacharparenleft}}SOME\ y{\isaliteral{2C}{\isacharcomma}}\ AQueue\ {\isaliteral{28}{\isacharparenleft}}xs{\isaliteral{2C}{\isacharcomma}}\ ys{\isaliteral{29}{\isacharparenright}}{\isaliteral{29}{\isacharparenright}}\isanewline
       
   163 \ \ {\isaliteral{7C}{\isacharbar}}\ dequeue\ {\isaliteral{28}{\isacharparenleft}}AQueue\ {\isaliteral{28}{\isacharparenleft}}v\ {\isaliteral{3A}{\isacharcolon}}{\isaliteral{3A}{\isacharcolon}}\ va{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{5B}{\isacharbrackleft}}{\isaliteral{5D}{\isacharbrackright}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{29}{\isacharparenright}}\ {\isaliteral{3D}{\isacharequal}}\isanewline
       
   164 \ \ \ \ let\isanewline
       
   165 \ \ \ \ \ \ val\ y\ {\isaliteral{3A}{\isacharcolon}}{\isaliteral{3A}{\isacharcolon}}\ ys\ {\isaliteral{3D}{\isacharequal}}\ rev\ {\isaliteral{28}{\isacharparenleft}}v\ {\isaliteral{3A}{\isacharcolon}}{\isaliteral{3A}{\isacharcolon}}\ va{\isaliteral{29}{\isacharparenright}}{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   166 \ \ \ \ in\isanewline
       
   167 \ \ \ \ \ \ {\isaliteral{28}{\isacharparenleft}}SOME\ y{\isaliteral{2C}{\isacharcomma}}\ AQueue\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{5B}{\isacharbrackleft}}{\isaliteral{5D}{\isacharbrackright}}{\isaliteral{2C}{\isacharcomma}}\ ys{\isaliteral{29}{\isacharparenright}}{\isaliteral{29}{\isacharparenright}}\isanewline
       
   168 \ \ \ \ end{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   169 \isanewline
       
   170 fun\ enqueue\ x\ {\isaliteral{28}{\isacharparenleft}}AQueue\ {\isaliteral{28}{\isacharparenleft}}xs{\isaliteral{2C}{\isacharcomma}}\ ys{\isaliteral{29}{\isacharparenright}}{\isaliteral{29}{\isacharparenright}}\ {\isaliteral{3D}{\isacharequal}}\ AQueue\ {\isaliteral{28}{\isacharparenleft}}x\ {\isaliteral{3A}{\isacharcolon}}{\isaliteral{3A}{\isacharcolon}}\ xs{\isaliteral{2C}{\isacharcomma}}\ ys{\isaliteral{29}{\isacharparenright}}{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   171 \isanewline
       
   172 end{\isaliteral{3B}{\isacharsemicolon}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{2A}{\isacharasterisk}}struct\ Example{\isaliteral{2A}{\isacharasterisk}}{\isaliteral{29}{\isacharparenright}}\isanewline%
       
   173 \end{isamarkuptext}%
       
   174 \isamarkuptrue%
       
   175 %
       
   176 \endisatagquotetypewriter
       
   177 {\isafoldquotetypewriter}%
       
   178 %
       
   179 \isadelimquotetypewriter
       
   180 %
       
   181 \endisadelimquotetypewriter
       
   182 %
       
   183 \begin{isamarkuptext}%
       
   184 \noindent The \indexdef{}{command}{export\_code}\hypertarget{command.export-code}{\hyperlink{command.export-code}{\mbox{\isa{\isacommand{export{\isaliteral{5F}{\isacharunderscore}}code}}}}} command takes a
       
   185   space-separated list of constants for which code shall be generated;
       
   186   anything else needed for those is added implicitly.  Then follows a
       
   187   target language identifier and a freely chosen module name.  A file
       
   188   name denotes the destination to store the generated code.  Note that
       
   189   the semantics of the destination depends on the target language: for
       
   190   \isa{SML}, \isa{OCaml} and \isa{Scala} it denotes a \emph{file},
       
   191   for \isa{Haskell} it denotes a \emph{directory} where a file named as the
       
   192   module name (with extension \isa{{\isaliteral{2E}{\isachardot}}hs}) is written:%
       
   193 \end{isamarkuptext}%
       
   194 \isamarkuptrue%
       
   195 %
       
   196 \isadelimquote
       
   197 %
       
   198 \endisadelimquote
       
   199 %
       
   200 \isatagquote
       
   201 \isacommand{export{\isaliteral{5F}{\isacharunderscore}}code}\isamarkupfalse%
       
   202 \ empty\ dequeue\ enqueue\ \isakeyword{in}\ Haskell\isanewline
       
   203 \ \ \isakeyword{module{\isaliteral{5F}{\isacharunderscore}}name}\ Example\ \isakeyword{file}\ {\isaliteral{22}{\isachardoublequoteopen}}examples{\isaliteral{2F}{\isacharslash}}{\isaliteral{22}{\isachardoublequoteclose}}%
       
   204 \endisatagquote
       
   205 {\isafoldquote}%
       
   206 %
       
   207 \isadelimquote
       
   208 %
       
   209 \endisadelimquote
       
   210 %
       
   211 \begin{isamarkuptext}%
       
   212 \noindent This is the corresponding code:%
       
   213 \end{isamarkuptext}%
       
   214 \isamarkuptrue%
       
   215 %
       
   216 \isadelimquotetypewriter
       
   217 %
       
   218 \endisadelimquotetypewriter
       
   219 %
       
   220 \isatagquotetypewriter
       
   221 %
       
   222 \begin{isamarkuptext}%
       
   223 module\ Example\ where\ {\isaliteral{7B}{\isacharbraceleft}}\isanewline
       
   224 \isanewline
       
   225 import\ Prelude\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{28}{\isacharparenleft}}{\isaliteral{3D}{\isacharequal}}{\isaliteral{3D}{\isacharequal}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{2F}{\isacharslash}}{\isaliteral{3D}{\isacharequal}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{3C}{\isacharless}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{3C}{\isacharless}}{\isaliteral{3D}{\isacharequal}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{3E}{\isachargreater}}{\isaliteral{3D}{\isacharequal}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{3E}{\isachargreater}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{2B}{\isacharplus}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{2D}{\isacharminus}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{2A}{\isacharasterisk}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{2F}{\isacharslash}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\isanewline
       
   226 \ \ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{2A}{\isacharasterisk}}{\isaliteral{2A}{\isacharasterisk}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{3E}{\isachargreater}}{\isaliteral{3E}{\isachargreater}}{\isaliteral{3D}{\isacharequal}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{3E}{\isachargreater}}{\isaliteral{3E}{\isachargreater}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{3D}{\isacharequal}}{\isaliteral{3C}{\isacharless}}{\isaliteral{3C}{\isacharless}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{26}{\isacharampersand}}{\isaliteral{26}{\isacharampersand}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{7C}{\isacharbar}}{\isaliteral{7C}{\isacharbar}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{5E}{\isacharcircum}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{5E}{\isacharcircum}}{\isaliteral{5E}{\isacharcircum}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{2E}{\isachardot}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{24}{\isachardollar}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{24}{\isachardollar}}{\isaliteral{21}{\isacharbang}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{2B}{\isacharplus}}{\isaliteral{2B}{\isacharplus}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\isanewline
       
   227 \ \ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{21}{\isacharbang}}{\isaliteral{21}{\isacharbang}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ Eq{\isaliteral{2C}{\isacharcomma}}\ error{\isaliteral{2C}{\isacharcomma}}\ id{\isaliteral{2C}{\isacharcomma}}\ return{\isaliteral{2C}{\isacharcomma}}\ not{\isaliteral{2C}{\isacharcomma}}\ fst{\isaliteral{2C}{\isacharcomma}}\ snd{\isaliteral{2C}{\isacharcomma}}\ map{\isaliteral{2C}{\isacharcomma}}\ filter{\isaliteral{2C}{\isacharcomma}}\ concat{\isaliteral{2C}{\isacharcomma}}\isanewline
       
   228 \ \ concatMap{\isaliteral{2C}{\isacharcomma}}\ reverse{\isaliteral{2C}{\isacharcomma}}\ zip{\isaliteral{2C}{\isacharcomma}}\ null{\isaliteral{2C}{\isacharcomma}}\ takeWhile{\isaliteral{2C}{\isacharcomma}}\ dropWhile{\isaliteral{2C}{\isacharcomma}}\ all{\isaliteral{2C}{\isacharcomma}}\ any{\isaliteral{2C}{\isacharcomma}}\ Integer{\isaliteral{2C}{\isacharcomma}}\isanewline
       
   229 \ \ negate{\isaliteral{2C}{\isacharcomma}}\ abs{\isaliteral{2C}{\isacharcomma}}\ divMod{\isaliteral{2C}{\isacharcomma}}\ String{\isaliteral{2C}{\isacharcomma}}\ Bool{\isaliteral{28}{\isacharparenleft}}True{\isaliteral{2C}{\isacharcomma}}\ False{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ Maybe{\isaliteral{28}{\isacharparenleft}}Nothing{\isaliteral{2C}{\isacharcomma}}\ Just{\isaliteral{29}{\isacharparenright}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   230 import\ qualified\ Prelude{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   231 \isanewline
       
   232 data\ Queue\ a\ {\isaliteral{3D}{\isacharequal}}\ AQueue\ {\isaliteral{5B}{\isacharbrackleft}}a{\isaliteral{5D}{\isacharbrackright}}\ {\isaliteral{5B}{\isacharbrackleft}}a{\isaliteral{5D}{\isacharbrackright}}{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   233 \isanewline
       
   234 empty\ {\isaliteral{3A}{\isacharcolon}}{\isaliteral{3A}{\isacharcolon}}\ forall\ a{\isaliteral{2E}{\isachardot}}\ Queue\ a{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   235 empty\ {\isaliteral{3D}{\isacharequal}}\ AQueue\ {\isaliteral{5B}{\isacharbrackleft}}{\isaliteral{5D}{\isacharbrackright}}\ {\isaliteral{5B}{\isacharbrackleft}}{\isaliteral{5D}{\isacharbrackright}}{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   236 \isanewline
       
   237 dequeue\ {\isaliteral{3A}{\isacharcolon}}{\isaliteral{3A}{\isacharcolon}}\ forall\ a{\isaliteral{2E}{\isachardot}}\ Queue\ a\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ {\isaliteral{28}{\isacharparenleft}}Maybe\ a{\isaliteral{2C}{\isacharcomma}}\ Queue\ a{\isaliteral{29}{\isacharparenright}}{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   238 dequeue\ {\isaliteral{28}{\isacharparenleft}}AQueue\ {\isaliteral{5B}{\isacharbrackleft}}{\isaliteral{5D}{\isacharbrackright}}\ {\isaliteral{5B}{\isacharbrackleft}}{\isaliteral{5D}{\isacharbrackright}}{\isaliteral{29}{\isacharparenright}}\ {\isaliteral{3D}{\isacharequal}}\ {\isaliteral{28}{\isacharparenleft}}Nothing{\isaliteral{2C}{\isacharcomma}}\ AQueue\ {\isaliteral{5B}{\isacharbrackleft}}{\isaliteral{5D}{\isacharbrackright}}\ {\isaliteral{5B}{\isacharbrackleft}}{\isaliteral{5D}{\isacharbrackright}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   239 dequeue\ {\isaliteral{28}{\isacharparenleft}}AQueue\ xs\ {\isaliteral{28}{\isacharparenleft}}y\ {\isaliteral{3A}{\isacharcolon}}\ ys{\isaliteral{29}{\isacharparenright}}{\isaliteral{29}{\isacharparenright}}\ {\isaliteral{3D}{\isacharequal}}\ {\isaliteral{28}{\isacharparenleft}}Just\ y{\isaliteral{2C}{\isacharcomma}}\ AQueue\ xs\ ys{\isaliteral{29}{\isacharparenright}}{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   240 dequeue\ {\isaliteral{28}{\isacharparenleft}}AQueue\ {\isaliteral{28}{\isacharparenleft}}v\ {\isaliteral{3A}{\isacharcolon}}\ va{\isaliteral{29}{\isacharparenright}}\ {\isaliteral{5B}{\isacharbrackleft}}{\isaliteral{5D}{\isacharbrackright}}{\isaliteral{29}{\isacharparenright}}\ {\isaliteral{3D}{\isacharequal}}\isanewline
       
   241 \ \ let\ {\isaliteral{7B}{\isacharbraceleft}}\isanewline
       
   242 \ \ \ \ {\isaliteral{28}{\isacharparenleft}}y\ {\isaliteral{3A}{\isacharcolon}}\ ys{\isaliteral{29}{\isacharparenright}}\ {\isaliteral{3D}{\isacharequal}}\ reverse\ {\isaliteral{28}{\isacharparenleft}}v\ {\isaliteral{3A}{\isacharcolon}}\ va{\isaliteral{29}{\isacharparenright}}{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   243 \ \ {\isaliteral{7D}{\isacharbraceright}}\ in\ {\isaliteral{28}{\isacharparenleft}}Just\ y{\isaliteral{2C}{\isacharcomma}}\ AQueue\ {\isaliteral{5B}{\isacharbrackleft}}{\isaliteral{5D}{\isacharbrackright}}\ ys{\isaliteral{29}{\isacharparenright}}{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   244 \isanewline
       
   245 enqueue\ {\isaliteral{3A}{\isacharcolon}}{\isaliteral{3A}{\isacharcolon}}\ forall\ a{\isaliteral{2E}{\isachardot}}\ a\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ Queue\ a\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ Queue\ a{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   246 enqueue\ x\ {\isaliteral{28}{\isacharparenleft}}AQueue\ xs\ ys{\isaliteral{29}{\isacharparenright}}\ {\isaliteral{3D}{\isacharequal}}\ AQueue\ {\isaliteral{28}{\isacharparenleft}}x\ {\isaliteral{3A}{\isacharcolon}}\ xs{\isaliteral{29}{\isacharparenright}}\ ys{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   247 \isanewline
       
   248 {\isaliteral{7D}{\isacharbraceright}}\isanewline%
       
   249 \end{isamarkuptext}%
       
   250 \isamarkuptrue%
       
   251 %
       
   252 \endisatagquotetypewriter
       
   253 {\isafoldquotetypewriter}%
       
   254 %
       
   255 \isadelimquotetypewriter
       
   256 %
       
   257 \endisadelimquotetypewriter
       
   258 %
       
   259 \begin{isamarkuptext}%
       
   260 \noindent For more details about \hyperlink{command.export-code}{\mbox{\isa{\isacommand{export{\isaliteral{5F}{\isacharunderscore}}code}}}} see
       
   261   \secref{sec:further}.%
       
   262 \end{isamarkuptext}%
       
   263 \isamarkuptrue%
       
   264 %
       
   265 \isamarkupsubsection{Type classes%
       
   266 }
       
   267 \isamarkuptrue%
       
   268 %
       
   269 \begin{isamarkuptext}%
       
   270 Code can also be generated from type classes in a Haskell-like
       
   271   manner.  For illustration here an example from abstract algebra:%
       
   272 \end{isamarkuptext}%
       
   273 \isamarkuptrue%
       
   274 %
       
   275 \isadelimquote
       
   276 %
       
   277 \endisadelimquote
       
   278 %
       
   279 \isatagquote
       
   280 \isacommand{class}\isamarkupfalse%
       
   281 \ semigroup\ {\isaliteral{3D}{\isacharequal}}\isanewline
       
   282 \ \ \isakeyword{fixes}\ mult\ {\isaliteral{3A}{\isacharcolon}}{\isaliteral{3A}{\isacharcolon}}\ {\isaliteral{22}{\isachardoublequoteopen}}{\isaliteral{27}{\isacharprime}}a\ {\isaliteral{5C3C52696768746172726F773E}{\isasymRightarrow}}\ {\isaliteral{27}{\isacharprime}}a\ {\isaliteral{5C3C52696768746172726F773E}{\isasymRightarrow}}\ {\isaliteral{27}{\isacharprime}}a{\isaliteral{22}{\isachardoublequoteclose}}\ {\isaliteral{28}{\isacharparenleft}}\isakeyword{infixl}\ {\isaliteral{22}{\isachardoublequoteopen}}{\isaliteral{5C3C6F74696D65733E}{\isasymotimes}}{\isaliteral{22}{\isachardoublequoteclose}}\ {\isadigit{7}}{\isadigit{0}}{\isaliteral{29}{\isacharparenright}}\isanewline
       
   283 \ \ \isakeyword{assumes}\ assoc{\isaliteral{3A}{\isacharcolon}}\ {\isaliteral{22}{\isachardoublequoteopen}}{\isaliteral{28}{\isacharparenleft}}x\ {\isaliteral{5C3C6F74696D65733E}{\isasymotimes}}\ y{\isaliteral{29}{\isacharparenright}}\ {\isaliteral{5C3C6F74696D65733E}{\isasymotimes}}\ z\ {\isaliteral{3D}{\isacharequal}}\ x\ {\isaliteral{5C3C6F74696D65733E}{\isasymotimes}}\ {\isaliteral{28}{\isacharparenleft}}y\ {\isaliteral{5C3C6F74696D65733E}{\isasymotimes}}\ z{\isaliteral{29}{\isacharparenright}}{\isaliteral{22}{\isachardoublequoteclose}}\isanewline
       
   284 \isanewline
       
   285 \isacommand{class}\isamarkupfalse%
       
   286 \ monoid\ {\isaliteral{3D}{\isacharequal}}\ semigroup\ {\isaliteral{2B}{\isacharplus}}\isanewline
       
   287 \ \ \isakeyword{fixes}\ neutral\ {\isaliteral{3A}{\isacharcolon}}{\isaliteral{3A}{\isacharcolon}}\ {\isaliteral{27}{\isacharprime}}a\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{22}{\isachardoublequoteopen}}{\isaliteral{5C3C6F6E653E}{\isasymone}}{\isaliteral{22}{\isachardoublequoteclose}}{\isaliteral{29}{\isacharparenright}}\isanewline
       
   288 \ \ \isakeyword{assumes}\ neutl{\isaliteral{3A}{\isacharcolon}}\ {\isaliteral{22}{\isachardoublequoteopen}}{\isaliteral{5C3C6F6E653E}{\isasymone}}\ {\isaliteral{5C3C6F74696D65733E}{\isasymotimes}}\ x\ {\isaliteral{3D}{\isacharequal}}\ x{\isaliteral{22}{\isachardoublequoteclose}}\isanewline
       
   289 \ \ \ \ \isakeyword{and}\ neutr{\isaliteral{3A}{\isacharcolon}}\ {\isaliteral{22}{\isachardoublequoteopen}}x\ {\isaliteral{5C3C6F74696D65733E}{\isasymotimes}}\ {\isaliteral{5C3C6F6E653E}{\isasymone}}\ {\isaliteral{3D}{\isacharequal}}\ x{\isaliteral{22}{\isachardoublequoteclose}}\isanewline
       
   290 \isanewline
       
   291 \isacommand{instantiation}\isamarkupfalse%
       
   292 \ nat\ {\isaliteral{3A}{\isacharcolon}}{\isaliteral{3A}{\isacharcolon}}\ monoid\isanewline
       
   293 \isakeyword{begin}\isanewline
       
   294 \isanewline
       
   295 \isacommand{primrec}\isamarkupfalse%
       
   296 \ mult{\isaliteral{5F}{\isacharunderscore}}nat\ \isakeyword{where}\isanewline
       
   297 \ \ \ \ {\isaliteral{22}{\isachardoublequoteopen}}{\isadigit{0}}\ {\isaliteral{5C3C6F74696D65733E}{\isasymotimes}}\ n\ {\isaliteral{3D}{\isacharequal}}\ {\isaliteral{28}{\isacharparenleft}}{\isadigit{0}}{\isaliteral{5C3C436F6C6F6E3E}{\isasymColon}}nat{\isaliteral{29}{\isacharparenright}}{\isaliteral{22}{\isachardoublequoteclose}}\isanewline
       
   298 \ \ {\isaliteral{7C}{\isacharbar}}\ {\isaliteral{22}{\isachardoublequoteopen}}Suc\ m\ {\isaliteral{5C3C6F74696D65733E}{\isasymotimes}}\ n\ {\isaliteral{3D}{\isacharequal}}\ n\ {\isaliteral{2B}{\isacharplus}}\ m\ {\isaliteral{5C3C6F74696D65733E}{\isasymotimes}}\ n{\isaliteral{22}{\isachardoublequoteclose}}\isanewline
       
   299 \isanewline
       
   300 \isacommand{definition}\isamarkupfalse%
       
   301 \ neutral{\isaliteral{5F}{\isacharunderscore}}nat\ \isakeyword{where}\isanewline
       
   302 \ \ {\isaliteral{22}{\isachardoublequoteopen}}{\isaliteral{5C3C6F6E653E}{\isasymone}}\ {\isaliteral{3D}{\isacharequal}}\ Suc\ {\isadigit{0}}{\isaliteral{22}{\isachardoublequoteclose}}\isanewline
       
   303 \isanewline
       
   304 \isacommand{lemma}\isamarkupfalse%
       
   305 \ add{\isaliteral{5F}{\isacharunderscore}}mult{\isaliteral{5F}{\isacharunderscore}}distrib{\isaliteral{3A}{\isacharcolon}}\isanewline
       
   306 \ \ \isakeyword{fixes}\ n\ m\ q\ {\isaliteral{3A}{\isacharcolon}}{\isaliteral{3A}{\isacharcolon}}\ nat\isanewline
       
   307 \ \ \isakeyword{shows}\ {\isaliteral{22}{\isachardoublequoteopen}}{\isaliteral{28}{\isacharparenleft}}n\ {\isaliteral{2B}{\isacharplus}}\ m{\isaliteral{29}{\isacharparenright}}\ {\isaliteral{5C3C6F74696D65733E}{\isasymotimes}}\ q\ {\isaliteral{3D}{\isacharequal}}\ n\ {\isaliteral{5C3C6F74696D65733E}{\isasymotimes}}\ q\ {\isaliteral{2B}{\isacharplus}}\ m\ {\isaliteral{5C3C6F74696D65733E}{\isasymotimes}}\ q{\isaliteral{22}{\isachardoublequoteclose}}\isanewline
       
   308 \ \ \isacommand{by}\isamarkupfalse%
       
   309 \ {\isaliteral{28}{\isacharparenleft}}induct\ n{\isaliteral{29}{\isacharparenright}}\ simp{\isaliteral{5F}{\isacharunderscore}}all\isanewline
       
   310 \isanewline
       
   311 \isacommand{instance}\isamarkupfalse%
       
   312 \ \isacommand{proof}\isamarkupfalse%
       
   313 \isanewline
       
   314 \ \ \isacommand{fix}\isamarkupfalse%
       
   315 \ m\ n\ q\ {\isaliteral{3A}{\isacharcolon}}{\isaliteral{3A}{\isacharcolon}}\ nat\isanewline
       
   316 \ \ \isacommand{show}\isamarkupfalse%
       
   317 \ {\isaliteral{22}{\isachardoublequoteopen}}m\ {\isaliteral{5C3C6F74696D65733E}{\isasymotimes}}\ n\ {\isaliteral{5C3C6F74696D65733E}{\isasymotimes}}\ q\ {\isaliteral{3D}{\isacharequal}}\ m\ {\isaliteral{5C3C6F74696D65733E}{\isasymotimes}}\ {\isaliteral{28}{\isacharparenleft}}n\ {\isaliteral{5C3C6F74696D65733E}{\isasymotimes}}\ q{\isaliteral{29}{\isacharparenright}}{\isaliteral{22}{\isachardoublequoteclose}}\isanewline
       
   318 \ \ \ \ \isacommand{by}\isamarkupfalse%
       
   319 \ {\isaliteral{28}{\isacharparenleft}}induct\ m{\isaliteral{29}{\isacharparenright}}\ {\isaliteral{28}{\isacharparenleft}}simp{\isaliteral{5F}{\isacharunderscore}}all\ add{\isaliteral{3A}{\isacharcolon}}\ add{\isaliteral{5F}{\isacharunderscore}}mult{\isaliteral{5F}{\isacharunderscore}}distrib{\isaliteral{29}{\isacharparenright}}\isanewline
       
   320 \ \ \isacommand{show}\isamarkupfalse%
       
   321 \ {\isaliteral{22}{\isachardoublequoteopen}}{\isaliteral{5C3C6F6E653E}{\isasymone}}\ {\isaliteral{5C3C6F74696D65733E}{\isasymotimes}}\ n\ {\isaliteral{3D}{\isacharequal}}\ n{\isaliteral{22}{\isachardoublequoteclose}}\isanewline
       
   322 \ \ \ \ \isacommand{by}\isamarkupfalse%
       
   323 \ {\isaliteral{28}{\isacharparenleft}}simp\ add{\isaliteral{3A}{\isacharcolon}}\ neutral{\isaliteral{5F}{\isacharunderscore}}nat{\isaliteral{5F}{\isacharunderscore}}def{\isaliteral{29}{\isacharparenright}}\isanewline
       
   324 \ \ \isacommand{show}\isamarkupfalse%
       
   325 \ {\isaliteral{22}{\isachardoublequoteopen}}m\ {\isaliteral{5C3C6F74696D65733E}{\isasymotimes}}\ {\isaliteral{5C3C6F6E653E}{\isasymone}}\ {\isaliteral{3D}{\isacharequal}}\ m{\isaliteral{22}{\isachardoublequoteclose}}\isanewline
       
   326 \ \ \ \ \isacommand{by}\isamarkupfalse%
       
   327 \ {\isaliteral{28}{\isacharparenleft}}induct\ m{\isaliteral{29}{\isacharparenright}}\ {\isaliteral{28}{\isacharparenleft}}simp{\isaliteral{5F}{\isacharunderscore}}all\ add{\isaliteral{3A}{\isacharcolon}}\ neutral{\isaliteral{5F}{\isacharunderscore}}nat{\isaliteral{5F}{\isacharunderscore}}def{\isaliteral{29}{\isacharparenright}}\isanewline
       
   328 \isacommand{qed}\isamarkupfalse%
       
   329 \isanewline
       
   330 \isanewline
       
   331 \isacommand{end}\isamarkupfalse%
       
   332 %
       
   333 \endisatagquote
       
   334 {\isafoldquote}%
       
   335 %
       
   336 \isadelimquote
       
   337 %
       
   338 \endisadelimquote
       
   339 %
       
   340 \begin{isamarkuptext}%
       
   341 \noindent We define the natural operation of the natural numbers
       
   342   on monoids:%
       
   343 \end{isamarkuptext}%
       
   344 \isamarkuptrue%
       
   345 %
       
   346 \isadelimquote
       
   347 %
       
   348 \endisadelimquote
       
   349 %
       
   350 \isatagquote
       
   351 \isacommand{primrec}\isamarkupfalse%
       
   352 \ {\isaliteral{28}{\isacharparenleft}}\isakeyword{in}\ monoid{\isaliteral{29}{\isacharparenright}}\ pow\ {\isaliteral{3A}{\isacharcolon}}{\isaliteral{3A}{\isacharcolon}}\ {\isaliteral{22}{\isachardoublequoteopen}}nat\ {\isaliteral{5C3C52696768746172726F773E}{\isasymRightarrow}}\ {\isaliteral{27}{\isacharprime}}a\ {\isaliteral{5C3C52696768746172726F773E}{\isasymRightarrow}}\ {\isaliteral{27}{\isacharprime}}a{\isaliteral{22}{\isachardoublequoteclose}}\ \isakeyword{where}\isanewline
       
   353 \ \ \ \ {\isaliteral{22}{\isachardoublequoteopen}}pow\ {\isadigit{0}}\ a\ {\isaliteral{3D}{\isacharequal}}\ {\isaliteral{5C3C6F6E653E}{\isasymone}}{\isaliteral{22}{\isachardoublequoteclose}}\isanewline
       
   354 \ \ {\isaliteral{7C}{\isacharbar}}\ {\isaliteral{22}{\isachardoublequoteopen}}pow\ {\isaliteral{28}{\isacharparenleft}}Suc\ n{\isaliteral{29}{\isacharparenright}}\ a\ {\isaliteral{3D}{\isacharequal}}\ a\ {\isaliteral{5C3C6F74696D65733E}{\isasymotimes}}\ pow\ n\ a{\isaliteral{22}{\isachardoublequoteclose}}%
       
   355 \endisatagquote
       
   356 {\isafoldquote}%
       
   357 %
       
   358 \isadelimquote
       
   359 %
       
   360 \endisadelimquote
       
   361 %
       
   362 \begin{isamarkuptext}%
       
   363 \noindent This we use to define the discrete exponentiation
       
   364   function:%
       
   365 \end{isamarkuptext}%
       
   366 \isamarkuptrue%
       
   367 %
       
   368 \isadelimquote
       
   369 %
       
   370 \endisadelimquote
       
   371 %
       
   372 \isatagquote
       
   373 \isacommand{definition}\isamarkupfalse%
       
   374 \ bexp\ {\isaliteral{3A}{\isacharcolon}}{\isaliteral{3A}{\isacharcolon}}\ {\isaliteral{22}{\isachardoublequoteopen}}nat\ {\isaliteral{5C3C52696768746172726F773E}{\isasymRightarrow}}\ nat{\isaliteral{22}{\isachardoublequoteclose}}\ \isakeyword{where}\isanewline
       
   375 \ \ {\isaliteral{22}{\isachardoublequoteopen}}bexp\ n\ {\isaliteral{3D}{\isacharequal}}\ pow\ n\ {\isaliteral{28}{\isacharparenleft}}Suc\ {\isaliteral{28}{\isacharparenleft}}Suc\ {\isadigit{0}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{22}{\isachardoublequoteclose}}%
       
   376 \endisatagquote
       
   377 {\isafoldquote}%
       
   378 %
       
   379 \isadelimquote
       
   380 %
       
   381 \endisadelimquote
       
   382 %
       
   383 \begin{isamarkuptext}%
       
   384 \noindent The corresponding code in Haskell uses that language's
       
   385   native classes:%
       
   386 \end{isamarkuptext}%
       
   387 \isamarkuptrue%
       
   388 %
       
   389 \isadelimquotetypewriter
       
   390 %
       
   391 \endisadelimquotetypewriter
       
   392 %
       
   393 \isatagquotetypewriter
       
   394 %
       
   395 \begin{isamarkuptext}%
       
   396 module\ Example\ where\ {\isaliteral{7B}{\isacharbraceleft}}\isanewline
       
   397 \isanewline
       
   398 import\ Prelude\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{28}{\isacharparenleft}}{\isaliteral{3D}{\isacharequal}}{\isaliteral{3D}{\isacharequal}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{2F}{\isacharslash}}{\isaliteral{3D}{\isacharequal}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{3C}{\isacharless}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{3C}{\isacharless}}{\isaliteral{3D}{\isacharequal}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{3E}{\isachargreater}}{\isaliteral{3D}{\isacharequal}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{3E}{\isachargreater}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{2B}{\isacharplus}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{2D}{\isacharminus}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{2A}{\isacharasterisk}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{2F}{\isacharslash}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\isanewline
       
   399 \ \ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{2A}{\isacharasterisk}}{\isaliteral{2A}{\isacharasterisk}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{3E}{\isachargreater}}{\isaliteral{3E}{\isachargreater}}{\isaliteral{3D}{\isacharequal}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{3E}{\isachargreater}}{\isaliteral{3E}{\isachargreater}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{3D}{\isacharequal}}{\isaliteral{3C}{\isacharless}}{\isaliteral{3C}{\isacharless}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{26}{\isacharampersand}}{\isaliteral{26}{\isacharampersand}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{7C}{\isacharbar}}{\isaliteral{7C}{\isacharbar}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{5E}{\isacharcircum}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{5E}{\isacharcircum}}{\isaliteral{5E}{\isacharcircum}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{2E}{\isachardot}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{24}{\isachardollar}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{24}{\isachardollar}}{\isaliteral{21}{\isacharbang}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{2B}{\isacharplus}}{\isaliteral{2B}{\isacharplus}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\isanewline
       
   400 \ \ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{21}{\isacharbang}}{\isaliteral{21}{\isacharbang}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ Eq{\isaliteral{2C}{\isacharcomma}}\ error{\isaliteral{2C}{\isacharcomma}}\ id{\isaliteral{2C}{\isacharcomma}}\ return{\isaliteral{2C}{\isacharcomma}}\ not{\isaliteral{2C}{\isacharcomma}}\ fst{\isaliteral{2C}{\isacharcomma}}\ snd{\isaliteral{2C}{\isacharcomma}}\ map{\isaliteral{2C}{\isacharcomma}}\ filter{\isaliteral{2C}{\isacharcomma}}\ concat{\isaliteral{2C}{\isacharcomma}}\isanewline
       
   401 \ \ concatMap{\isaliteral{2C}{\isacharcomma}}\ reverse{\isaliteral{2C}{\isacharcomma}}\ zip{\isaliteral{2C}{\isacharcomma}}\ null{\isaliteral{2C}{\isacharcomma}}\ takeWhile{\isaliteral{2C}{\isacharcomma}}\ dropWhile{\isaliteral{2C}{\isacharcomma}}\ all{\isaliteral{2C}{\isacharcomma}}\ any{\isaliteral{2C}{\isacharcomma}}\ Integer{\isaliteral{2C}{\isacharcomma}}\isanewline
       
   402 \ \ negate{\isaliteral{2C}{\isacharcomma}}\ abs{\isaliteral{2C}{\isacharcomma}}\ divMod{\isaliteral{2C}{\isacharcomma}}\ String{\isaliteral{2C}{\isacharcomma}}\ Bool{\isaliteral{28}{\isacharparenleft}}True{\isaliteral{2C}{\isacharcomma}}\ False{\isaliteral{29}{\isacharparenright}}{\isaliteral{2C}{\isacharcomma}}\ Maybe{\isaliteral{28}{\isacharparenleft}}Nothing{\isaliteral{2C}{\isacharcomma}}\ Just{\isaliteral{29}{\isacharparenright}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   403 import\ qualified\ Prelude{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   404 \isanewline
       
   405 data\ Nat\ {\isaliteral{3D}{\isacharequal}}\ Zero{\isaliteral{5F}{\isacharunderscore}}nat\ {\isaliteral{7C}{\isacharbar}}\ Suc\ Nat{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   406 \isanewline
       
   407 plus{\isaliteral{5F}{\isacharunderscore}}nat\ {\isaliteral{3A}{\isacharcolon}}{\isaliteral{3A}{\isacharcolon}}\ Nat\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ Nat\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ Nat{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   408 plus{\isaliteral{5F}{\isacharunderscore}}nat\ {\isaliteral{28}{\isacharparenleft}}Suc\ m{\isaliteral{29}{\isacharparenright}}\ n\ {\isaliteral{3D}{\isacharequal}}\ plus{\isaliteral{5F}{\isacharunderscore}}nat\ m\ {\isaliteral{28}{\isacharparenleft}}Suc\ n{\isaliteral{29}{\isacharparenright}}{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   409 plus{\isaliteral{5F}{\isacharunderscore}}nat\ Zero{\isaliteral{5F}{\isacharunderscore}}nat\ n\ {\isaliteral{3D}{\isacharequal}}\ n{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   410 \isanewline
       
   411 class\ Semigroup\ a\ where\ {\isaliteral{7B}{\isacharbraceleft}}\isanewline
       
   412 \ \ mult\ {\isaliteral{3A}{\isacharcolon}}{\isaliteral{3A}{\isacharcolon}}\ a\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ a\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ a{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   413 {\isaliteral{7D}{\isacharbraceright}}{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   414 \isanewline
       
   415 class\ {\isaliteral{28}{\isacharparenleft}}Semigroup\ a{\isaliteral{29}{\isacharparenright}}\ {\isaliteral{3D}{\isacharequal}}{\isaliteral{3E}{\isachargreater}}\ Monoid\ a\ where\ {\isaliteral{7B}{\isacharbraceleft}}\isanewline
       
   416 \ \ neutral\ {\isaliteral{3A}{\isacharcolon}}{\isaliteral{3A}{\isacharcolon}}\ a{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   417 {\isaliteral{7D}{\isacharbraceright}}{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   418 \isanewline
       
   419 pow\ {\isaliteral{3A}{\isacharcolon}}{\isaliteral{3A}{\isacharcolon}}\ forall\ a{\isaliteral{2E}{\isachardot}}\ {\isaliteral{28}{\isacharparenleft}}Monoid\ a{\isaliteral{29}{\isacharparenright}}\ {\isaliteral{3D}{\isacharequal}}{\isaliteral{3E}{\isachargreater}}\ Nat\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ a\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ a{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   420 pow\ Zero{\isaliteral{5F}{\isacharunderscore}}nat\ a\ {\isaliteral{3D}{\isacharequal}}\ neutral{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   421 pow\ {\isaliteral{28}{\isacharparenleft}}Suc\ n{\isaliteral{29}{\isacharparenright}}\ a\ {\isaliteral{3D}{\isacharequal}}\ mult\ a\ {\isaliteral{28}{\isacharparenleft}}pow\ n\ a{\isaliteral{29}{\isacharparenright}}{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   422 \isanewline
       
   423 mult{\isaliteral{5F}{\isacharunderscore}}nat\ {\isaliteral{3A}{\isacharcolon}}{\isaliteral{3A}{\isacharcolon}}\ Nat\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ Nat\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ Nat{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   424 mult{\isaliteral{5F}{\isacharunderscore}}nat\ Zero{\isaliteral{5F}{\isacharunderscore}}nat\ n\ {\isaliteral{3D}{\isacharequal}}\ Zero{\isaliteral{5F}{\isacharunderscore}}nat{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   425 mult{\isaliteral{5F}{\isacharunderscore}}nat\ {\isaliteral{28}{\isacharparenleft}}Suc\ m{\isaliteral{29}{\isacharparenright}}\ n\ {\isaliteral{3D}{\isacharequal}}\ plus{\isaliteral{5F}{\isacharunderscore}}nat\ n\ {\isaliteral{28}{\isacharparenleft}}mult{\isaliteral{5F}{\isacharunderscore}}nat\ m\ n{\isaliteral{29}{\isacharparenright}}{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   426 \isanewline
       
   427 instance\ Semigroup\ Nat\ where\ {\isaliteral{7B}{\isacharbraceleft}}\isanewline
       
   428 \ \ mult\ {\isaliteral{3D}{\isacharequal}}\ mult{\isaliteral{5F}{\isacharunderscore}}nat{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   429 {\isaliteral{7D}{\isacharbraceright}}{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   430 \isanewline
       
   431 neutral{\isaliteral{5F}{\isacharunderscore}}nat\ {\isaliteral{3A}{\isacharcolon}}{\isaliteral{3A}{\isacharcolon}}\ Nat{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   432 neutral{\isaliteral{5F}{\isacharunderscore}}nat\ {\isaliteral{3D}{\isacharequal}}\ Suc\ Zero{\isaliteral{5F}{\isacharunderscore}}nat{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   433 \isanewline
       
   434 instance\ Monoid\ Nat\ where\ {\isaliteral{7B}{\isacharbraceleft}}\isanewline
       
   435 \ \ neutral\ {\isaliteral{3D}{\isacharequal}}\ neutral{\isaliteral{5F}{\isacharunderscore}}nat{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   436 {\isaliteral{7D}{\isacharbraceright}}{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   437 \isanewline
       
   438 bexp\ {\isaliteral{3A}{\isacharcolon}}{\isaliteral{3A}{\isacharcolon}}\ Nat\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ Nat{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   439 bexp\ n\ {\isaliteral{3D}{\isacharequal}}\ pow\ n\ {\isaliteral{28}{\isacharparenleft}}Suc\ {\isaliteral{28}{\isacharparenleft}}Suc\ Zero{\isaliteral{5F}{\isacharunderscore}}nat{\isaliteral{29}{\isacharparenright}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   440 \isanewline
       
   441 {\isaliteral{7D}{\isacharbraceright}}\isanewline%
       
   442 \end{isamarkuptext}%
       
   443 \isamarkuptrue%
       
   444 %
       
   445 \endisatagquotetypewriter
       
   446 {\isafoldquotetypewriter}%
       
   447 %
       
   448 \isadelimquotetypewriter
       
   449 %
       
   450 \endisadelimquotetypewriter
       
   451 %
       
   452 \begin{isamarkuptext}%
       
   453 \noindent This is a convenient place to show how explicit dictionary
       
   454   construction manifests in generated code -- the same example in
       
   455   \isa{SML}:%
       
   456 \end{isamarkuptext}%
       
   457 \isamarkuptrue%
       
   458 %
       
   459 \isadelimquotetypewriter
       
   460 %
       
   461 \endisadelimquotetypewriter
       
   462 %
       
   463 \isatagquotetypewriter
       
   464 %
       
   465 \begin{isamarkuptext}%
       
   466 structure\ Example\ {\isaliteral{3A}{\isacharcolon}}\ sig\isanewline
       
   467 \ \ datatype\ nat\ {\isaliteral{3D}{\isacharequal}}\ Zero{\isaliteral{5F}{\isacharunderscore}}nat\ {\isaliteral{7C}{\isacharbar}}\ Suc\ of\ nat\isanewline
       
   468 \ \ val\ plus{\isaliteral{5F}{\isacharunderscore}}nat\ {\isaliteral{3A}{\isacharcolon}}\ nat\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ nat\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ nat\isanewline
       
   469 \ \ type\ {\isaliteral{27}{\isacharprime}}a\ semigroup\isanewline
       
   470 \ \ val\ mult\ {\isaliteral{3A}{\isacharcolon}}\ {\isaliteral{27}{\isacharprime}}a\ semigroup\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ {\isaliteral{27}{\isacharprime}}a\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ {\isaliteral{27}{\isacharprime}}a\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ {\isaliteral{27}{\isacharprime}}a\isanewline
       
   471 \ \ type\ {\isaliteral{27}{\isacharprime}}a\ monoid\isanewline
       
   472 \ \ val\ semigroup{\isaliteral{5F}{\isacharunderscore}}monoid\ {\isaliteral{3A}{\isacharcolon}}\ {\isaliteral{27}{\isacharprime}}a\ monoid\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ {\isaliteral{27}{\isacharprime}}a\ semigroup\isanewline
       
   473 \ \ val\ neutral\ {\isaliteral{3A}{\isacharcolon}}\ {\isaliteral{27}{\isacharprime}}a\ monoid\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ {\isaliteral{27}{\isacharprime}}a\isanewline
       
   474 \ \ val\ pow\ {\isaliteral{3A}{\isacharcolon}}\ {\isaliteral{27}{\isacharprime}}a\ monoid\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ nat\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ {\isaliteral{27}{\isacharprime}}a\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ {\isaliteral{27}{\isacharprime}}a\isanewline
       
   475 \ \ val\ mult{\isaliteral{5F}{\isacharunderscore}}nat\ {\isaliteral{3A}{\isacharcolon}}\ nat\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ nat\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ nat\isanewline
       
   476 \ \ val\ semigroup{\isaliteral{5F}{\isacharunderscore}}nat\ {\isaliteral{3A}{\isacharcolon}}\ nat\ semigroup\isanewline
       
   477 \ \ val\ neutral{\isaliteral{5F}{\isacharunderscore}}nat\ {\isaliteral{3A}{\isacharcolon}}\ nat\isanewline
       
   478 \ \ val\ monoid{\isaliteral{5F}{\isacharunderscore}}nat\ {\isaliteral{3A}{\isacharcolon}}\ nat\ monoid\isanewline
       
   479 \ \ val\ bexp\ {\isaliteral{3A}{\isacharcolon}}\ nat\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ nat\isanewline
       
   480 end\ {\isaliteral{3D}{\isacharequal}}\ struct\isanewline
       
   481 \isanewline
       
   482 datatype\ nat\ {\isaliteral{3D}{\isacharequal}}\ Zero{\isaliteral{5F}{\isacharunderscore}}nat\ {\isaliteral{7C}{\isacharbar}}\ Suc\ of\ nat{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   483 \isanewline
       
   484 fun\ plus{\isaliteral{5F}{\isacharunderscore}}nat\ {\isaliteral{28}{\isacharparenleft}}Suc\ m{\isaliteral{29}{\isacharparenright}}\ n\ {\isaliteral{3D}{\isacharequal}}\ plus{\isaliteral{5F}{\isacharunderscore}}nat\ m\ {\isaliteral{28}{\isacharparenleft}}Suc\ n{\isaliteral{29}{\isacharparenright}}\isanewline
       
   485 \ \ {\isaliteral{7C}{\isacharbar}}\ plus{\isaliteral{5F}{\isacharunderscore}}nat\ Zero{\isaliteral{5F}{\isacharunderscore}}nat\ n\ {\isaliteral{3D}{\isacharequal}}\ n{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   486 \isanewline
       
   487 type\ {\isaliteral{27}{\isacharprime}}a\ semigroup\ {\isaliteral{3D}{\isacharequal}}\ {\isaliteral{7B}{\isacharbraceleft}}mult\ {\isaliteral{3A}{\isacharcolon}}\ {\isaliteral{27}{\isacharprime}}a\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ {\isaliteral{27}{\isacharprime}}a\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ {\isaliteral{27}{\isacharprime}}a{\isaliteral{7D}{\isacharbraceright}}{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   488 val\ mult\ {\isaliteral{3D}{\isacharequal}}\ {\isaliteral{23}{\isacharhash}}mult\ {\isaliteral{3A}{\isacharcolon}}\ {\isaliteral{27}{\isacharprime}}a\ semigroup\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ {\isaliteral{27}{\isacharprime}}a\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ {\isaliteral{27}{\isacharprime}}a\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ {\isaliteral{27}{\isacharprime}}a{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   489 \isanewline
       
   490 type\ {\isaliteral{27}{\isacharprime}}a\ monoid\ {\isaliteral{3D}{\isacharequal}}\ {\isaliteral{7B}{\isacharbraceleft}}semigroup{\isaliteral{5F}{\isacharunderscore}}monoid\ {\isaliteral{3A}{\isacharcolon}}\ {\isaliteral{27}{\isacharprime}}a\ semigroup{\isaliteral{2C}{\isacharcomma}}\ neutral\ {\isaliteral{3A}{\isacharcolon}}\ {\isaliteral{27}{\isacharprime}}a{\isaliteral{7D}{\isacharbraceright}}{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   491 val\ semigroup{\isaliteral{5F}{\isacharunderscore}}monoid\ {\isaliteral{3D}{\isacharequal}}\ {\isaliteral{23}{\isacharhash}}semigroup{\isaliteral{5F}{\isacharunderscore}}monoid\ {\isaliteral{3A}{\isacharcolon}}\ {\isaliteral{27}{\isacharprime}}a\ monoid\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ {\isaliteral{27}{\isacharprime}}a\ semigroup{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   492 val\ neutral\ {\isaliteral{3D}{\isacharequal}}\ {\isaliteral{23}{\isacharhash}}neutral\ {\isaliteral{3A}{\isacharcolon}}\ {\isaliteral{27}{\isacharprime}}a\ monoid\ {\isaliteral{2D}{\isacharminus}}{\isaliteral{3E}{\isachargreater}}\ {\isaliteral{27}{\isacharprime}}a{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   493 \isanewline
       
   494 fun\ pow\ A{\isaliteral{5F}{\isacharunderscore}}\ Zero{\isaliteral{5F}{\isacharunderscore}}nat\ a\ {\isaliteral{3D}{\isacharequal}}\ neutral\ A{\isaliteral{5F}{\isacharunderscore}}\isanewline
       
   495 \ \ {\isaliteral{7C}{\isacharbar}}\ pow\ A{\isaliteral{5F}{\isacharunderscore}}\ {\isaliteral{28}{\isacharparenleft}}Suc\ n{\isaliteral{29}{\isacharparenright}}\ a\ {\isaliteral{3D}{\isacharequal}}\ mult\ {\isaliteral{28}{\isacharparenleft}}semigroup{\isaliteral{5F}{\isacharunderscore}}monoid\ A{\isaliteral{5F}{\isacharunderscore}}{\isaliteral{29}{\isacharparenright}}\ a\ {\isaliteral{28}{\isacharparenleft}}pow\ A{\isaliteral{5F}{\isacharunderscore}}\ n\ a{\isaliteral{29}{\isacharparenright}}{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   496 \isanewline
       
   497 fun\ mult{\isaliteral{5F}{\isacharunderscore}}nat\ Zero{\isaliteral{5F}{\isacharunderscore}}nat\ n\ {\isaliteral{3D}{\isacharequal}}\ Zero{\isaliteral{5F}{\isacharunderscore}}nat\isanewline
       
   498 \ \ {\isaliteral{7C}{\isacharbar}}\ mult{\isaliteral{5F}{\isacharunderscore}}nat\ {\isaliteral{28}{\isacharparenleft}}Suc\ m{\isaliteral{29}{\isacharparenright}}\ n\ {\isaliteral{3D}{\isacharequal}}\ plus{\isaliteral{5F}{\isacharunderscore}}nat\ n\ {\isaliteral{28}{\isacharparenleft}}mult{\isaliteral{5F}{\isacharunderscore}}nat\ m\ n{\isaliteral{29}{\isacharparenright}}{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   499 \isanewline
       
   500 val\ semigroup{\isaliteral{5F}{\isacharunderscore}}nat\ {\isaliteral{3D}{\isacharequal}}\ {\isaliteral{7B}{\isacharbraceleft}}mult\ {\isaliteral{3D}{\isacharequal}}\ mult{\isaliteral{5F}{\isacharunderscore}}nat{\isaliteral{7D}{\isacharbraceright}}\ {\isaliteral{3A}{\isacharcolon}}\ nat\ semigroup{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   501 \isanewline
       
   502 val\ neutral{\isaliteral{5F}{\isacharunderscore}}nat\ {\isaliteral{3A}{\isacharcolon}}\ nat\ {\isaliteral{3D}{\isacharequal}}\ Suc\ Zero{\isaliteral{5F}{\isacharunderscore}}nat{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   503 \isanewline
       
   504 val\ monoid{\isaliteral{5F}{\isacharunderscore}}nat\ {\isaliteral{3D}{\isacharequal}}\ {\isaliteral{7B}{\isacharbraceleft}}semigroup{\isaliteral{5F}{\isacharunderscore}}monoid\ {\isaliteral{3D}{\isacharequal}}\ semigroup{\isaliteral{5F}{\isacharunderscore}}nat{\isaliteral{2C}{\isacharcomma}}\ neutral\ {\isaliteral{3D}{\isacharequal}}\ neutral{\isaliteral{5F}{\isacharunderscore}}nat{\isaliteral{7D}{\isacharbraceright}}\isanewline
       
   505 \ \ {\isaliteral{3A}{\isacharcolon}}\ nat\ monoid{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   506 \isanewline
       
   507 fun\ bexp\ n\ {\isaliteral{3D}{\isacharequal}}\ pow\ monoid{\isaliteral{5F}{\isacharunderscore}}nat\ n\ {\isaliteral{28}{\isacharparenleft}}Suc\ {\isaliteral{28}{\isacharparenleft}}Suc\ Zero{\isaliteral{5F}{\isacharunderscore}}nat{\isaliteral{29}{\isacharparenright}}{\isaliteral{29}{\isacharparenright}}{\isaliteral{3B}{\isacharsemicolon}}\isanewline
       
   508 \isanewline
       
   509 end{\isaliteral{3B}{\isacharsemicolon}}\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{2A}{\isacharasterisk}}struct\ Example{\isaliteral{2A}{\isacharasterisk}}{\isaliteral{29}{\isacharparenright}}\isanewline%
       
   510 \end{isamarkuptext}%
       
   511 \isamarkuptrue%
       
   512 %
       
   513 \endisatagquotetypewriter
       
   514 {\isafoldquotetypewriter}%
       
   515 %
       
   516 \isadelimquotetypewriter
       
   517 %
       
   518 \endisadelimquotetypewriter
       
   519 %
       
   520 \begin{isamarkuptext}%
       
   521 \noindent Note the parameters with trailing underscore (\verb|A_|), which are the dictionary parameters.%
       
   522 \end{isamarkuptext}%
       
   523 \isamarkuptrue%
       
   524 %
       
   525 \isamarkupsubsection{How to continue from here%
       
   526 }
       
   527 \isamarkuptrue%
       
   528 %
       
   529 \begin{isamarkuptext}%
       
   530 What you have seen so far should be already enough in a lot of
       
   531   cases.  If you are content with this, you can quit reading here.
       
   532 
       
   533   Anyway, to understand situations where problems occur or to increase
       
   534   the scope of code generation beyond default, it is necessary to gain
       
   535   some understanding how the code generator actually works:
       
   536 
       
   537   \begin{itemize}
       
   538 
       
   539     \item The foundations of the code generator are described in
       
   540       \secref{sec:foundations}.
       
   541 
       
   542     \item In particular \secref{sec:utterly_wrong} gives hints how to
       
   543       debug situations where code generation does not succeed as
       
   544       expected.
       
   545 
       
   546     \item The scope and quality of generated code can be increased
       
   547       dramatically by applying refinement techniques, which are
       
   548       introduced in \secref{sec:refinement}.
       
   549 
       
   550     \item Inductive predicates can be turned executable using an
       
   551       extension of the code generator \secref{sec:inductive}.
       
   552 
       
   553     \item If you want to utilize code generation to obtain fast
       
   554       evaluators e.g.~for decision procedures, have a look at
       
   555       \secref{sec:evaluation}.
       
   556 
       
   557     \item You may want to skim over the more technical sections
       
   558       \secref{sec:adaptation} and \secref{sec:further}.
       
   559 
       
   560     \item The target language Scala \cite{scala-overview-tech-report}
       
   561       comes with some specialities discussed in \secref{sec:scala}.
       
   562 
       
   563     \item For exhaustive syntax diagrams etc. you should visit the
       
   564       Isabelle/Isar Reference Manual \cite{isabelle-isar-ref}.
       
   565 
       
   566   \end{itemize}
       
   567 
       
   568   \bigskip
       
   569 
       
   570   \begin{center}\fbox{\fbox{\begin{minipage}{8cm}
       
   571 
       
   572     \begin{center}\textit{Happy proving, happy hacking!}\end{center}
       
   573 
       
   574   \end{minipage}}}\end{center}%
       
   575 \end{isamarkuptext}%
       
   576 \isamarkuptrue%
       
   577 %
       
   578 \isadelimtheory
       
   579 %
       
   580 \endisadelimtheory
       
   581 %
       
   582 \isatagtheory
       
   583 \isacommand{end}\isamarkupfalse%
       
   584 %
       
   585 \endisatagtheory
       
   586 {\isafoldtheory}%
       
   587 %
       
   588 \isadelimtheory
       
   589 %
       
   590 \endisadelimtheory
       
   591 \isanewline
       
   592 \isanewline
       
   593 \end{isabellebody}%
       
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