theory Antiquotes

imports "../Base"

begin

section {* Useful Document Antiquotations *}

text {*

  {\bf Problem:} 

  How to keep your ML-code inside a document synchronised with the actual code?\smallskip

  {\bf Solution:} This can be achieved using document antiquotations.\smallskip

  Document antiquotations can be used for ensuring consistent type-setting of

  various entities in a document. They can also be used for sophisticated

  \LaTeX-hacking.

  Below we give the code for two antiquotations that can be used to typeset

  ML-code and also to check whether the given code actually compiles. This

  provides a sanity check for the code and also allows one to keep documents

  in sync with other code, for example Isabelle.

  We first describe the antiquotation @{text "@{ML_checked \"expr\"}"}. This

  by sending the ML-expression @{text [quotes] "val _ = \<dots>"} containing the

  given argument to the ML-compiler (i.e.~the function @{ML "ML_Context.eval_in"}

*}

  ThyOutput.output_list (fn _ => fn s => Pretty.str s) src ctxt 

val _ = ThyOutput.add_commands

*}

text {*

  Note that the parser @{ML "(Scan.lift Args.name)"} in line 9 parses a string, 

  If the code is ``approved'' by the compiler, then the output function @{ML

  "ThyOutput.output_list (fn _ => fn s => Pretty.str s)"} in the next line pretty prints the

  code. This function expects that the code is a list of strings where each

  that are observed by @{ML ThyOutput.output_list} when printing the code (for

  example @{text "[display]"}, @{text "[quotes]"} and @{text "[source]"}).

  \begin{readmore}

  For more information about options of antiquotations see \rsccite{sec:antiq}).

  \end{readmore}

  Since we used the argument @{ML "Position.none"}, the compiler cannot give specific 

*}

  ThyOutput.output_list (fn _ => fn s => Pretty.str s) src ctxt 

val _ = ThyOutput.add_commands

 [("ML_checked", ThyOutput.args 

*}

text {*

  where in Lines 1 and 2 the positional information is properly treated.

  (FIXME: say something about OuterParse.position)

  We can now write in a document @{text "@{ML_checked \"2 + 3\"}"} in order to

  obtain @{ML_checked "2 + 3"} and be sure that this code compiles until

  somebody changes the definition of \mbox{@{ML "(op +)"}}.

  The second antiquotation extends the first by allowing also to give

  @{text "@{ML_response \"expr\" \"pat\"}"}

  whose first argument is the ML-code and the second is a pattern specifying

*}

ML {* 

*}

text {* 

*}

ML {*

*}

text {* 

  The rest of the code of the antiquotation is

  *}

ML {*

val _ = ThyOutput.add_commands

 [("ML_response", 

     ThyOutput.args 

      (Scan.lift (OuterParse.position (Args.name -- Args.name))) 

*}

text {*

  This extended antiquotation allows us to write 

  @{text [display] "@{ML_response [display] \"true andalso false\" \"false\"}"}

  to obtain

@{ML_response [display] "true andalso false" "false"} 

  or 

@{text [display] "@{ML_response [display] \"let val i = 3 in (i * i,\"foo\") end\" \"(9,\<dots>)\"}"}

  to obtain

@{ML_response [display] "let val i = 3 in (i * i,\"foo\") end" "(9,\<dots>)"} 

  In both cases, the check by the compiler ensures that code and result match. A limitation

  of this antiquotation is that the hints can only be given for results that can actually

  be constructed as a pattern. This excludes values that are abstract datatypes, like 

  theorems or cterms.

*}

end