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theory Antiquotes+
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imports "../Appendix"+
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begin+
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+
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section \<open>Useful Document Antiquotations\label{rec:docantiquotations}\<close>+
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+
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text \<open>+
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  {\bf Problem:} +
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  How to keep your ML-code inside a document synchronised with the actual code?\smallskip+
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+
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  {\bf Solution:} This can be achieved with document antiquotations.\smallskip+
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+
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  Document antiquotations can be used for ensuring consistent type-setting of+
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  various entities in a document. They can also be used for sophisticated+
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  \LaTeX-hacking. If you type on the Isabelle level+
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\<close>+
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+
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print_antiquotations+
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+
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text \<open>+
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  you obtain a list of all currently available document antiquotations and+
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  their options.  +
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+
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  Below we will give the code for two additional document+
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  antiquotations both of which are intended to typeset ML-code. The crucial point+
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  of these document antiquotations is that they not just print the ML-code, but also +
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  check whether it compiles. This will provide a sanity check for the code+
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  and also allows you to keep documents in sync with other code, for example+
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  Isabelle.+
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+
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  We first describe the antiquotation \<open>ML_checked\<close> with the syntax:+
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 +
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  @{text [display] \<open>@{ML_checked "a_piece_of_code"}\<close>}+
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+
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  The code is checked by sending the ML-expression @{text [quotes] "val _ =+
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  a_piece_of_code"} to the ML-compiler (i.e.~the function @{ML \<open>ML_Context.eval_in\<close>} in Line 8 below). The complete code of the+
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  document antiquotation is as follows:+
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+
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\<close>+
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ML \<open>Input.pos_of\<close>+
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ML%linenosgray\<open>fun ml_enclose bg en source =+
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  ML_Lex.read bg @ ML_Lex.read_source source @ ML_Lex.read en;\<close>+
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+
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ML%linenosgray\<open>fun ml_val code_txt = (ml_enclose "val _ = " "" code_txt)+
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+
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fun output_ml ctxt code_txt =+
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let+
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  val _ = ML_Context.eval_in (SOME ctxt) ML_Compiler.flags +
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    (Input.pos_of code_txt) (ml_val code_txt)+
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in +
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   Pretty.str (fst (Input.source_content code_txt))+
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end+
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+
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val ml_checked_setup = Thy_Output.antiquotation_pretty_source +
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  @{binding "ML_checked"} (Scan.lift Args.text_input) output_ml\<close>+
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+
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setup \<open>ml_checked_setup\<close>+
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+
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+
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text \<open>+
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  The parser @{ML \<open>(Scan.lift Args.text_input)\<close>} in Line 15 parses a string, in this+
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  case the code, and then we call the function @{ML output_ml}. As mentioned+
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  before, the parsed code is sent to the ML-compiler in Line 8 using the+
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  function @{ML ml_val}, which constructs the appropriate ML-expression, and+
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  using @{ML \<open>eval_in\<close> in ML_Context}, which calls the compiler.  If the code is+
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  ``approved'' by the compiler, then the output given to @{ML \<open>antiquotation_pretty_source\<close> in+
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  Thy_Output} in the Line 15 pretty prints the code. This function expects+
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  that the code is (pretty) string. There are a+
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  number of options for antiquotations that are observed by the function +
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  @{ML \<open>output\<close> in Document_Antiquotation} when printing the code (including \<open>[display]\<close> +
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  and \<open>[quotes]\<close>). +
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+
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  \begin{readmore}+
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  For more information about options of document antiquotations see \rsccite{sec:antiq}).+
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  \end{readmore}+
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+
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\<close>+
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+
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text \<open>+
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  The second document antiquotation we describe extends the first by a pattern+
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  that specifies what the result of the ML-code should be and checks the+
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  consistency of the actual result with the given pattern. For this we are+
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  going to implement the document antiquotation:+
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+
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  +
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  @{text [display] \<open>@{ML_resp "a_piece_of_code" "a_pattern"}\<close>}+
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  +
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  To add some convenience and also to deal with large outputs, the user can+
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  give a partial specification by using ellipses. For example \<open>(\<dots>, \<dots>)\<close>+
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  for specifying a pair.  In order to check consistency between the pattern+
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  and the output of the code, we have to change the ML-expression that is sent +
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  to the compiler: +
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\<close>+
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+
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ML%linenosgray\<open>fun ml_pat pat code =+
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  ML_Lex.read "val" @ +
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  ML_Lex.read_source pat @ +
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  ML_Lex.read " = " @ +
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  ML_Lex.read_source code\<close>+
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+
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text \<open>+
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  Next we add a response indicator to the result using:+
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\<close>+
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+
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ML %grayML\<open>fun add_resp pat = map (fn s => "> " ^ s) pat\<close>+
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+
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text \<open>+
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  The rest of the code of \<open>ML_resp\<close> is: +
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\<close>+
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+
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ML %linenosgray\<open>+
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fun output_ml_resp ctxt (code_txt, pat) =+
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let+
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  val _ = ML_Context.eval_in (SOME ctxt) ML_Compiler.flags +
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    (Input.pos_of code_txt) (ml_pat pat code_txt)+
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  val code = space_explode "\n" (fst (Input.source_content code_txt))+
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  val resp = add_resp (space_explode "\n" (fst (Input.source_content pat)))+
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in +
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   Pretty.str (cat_lines (code @ resp))+
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end+
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+
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val ml_response_setup = Thy_Output.antiquotation_pretty_source +
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  @{binding "ML_resp"} +
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  (Scan.lift (Args.text_input -- Args.text_input)) +
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  output_ml_resp+
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+
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\<close>+
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+
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setup \<open>ml_response_setup\<close>+
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+
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(* FIXME *)+
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text \<open>+
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  In comparison with \<open>ML_checked\<close>, we changed the line about +
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  the compiler (Lines 4 to 5), the lines about+
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  the output (Lines 6 to 7 and 9) and the parser setup (Line 14). Now +
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  you can write+
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 +
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  @{text [display] \<open>@{ML_resp [display] "true andalso false" "false"}\<close>}+
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+
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  to obtain+
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+
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  @{ML_resp [display] "true andalso false" "false"} +
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+
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  or +
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+
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  @{text [display] \<open>@{ML_resp [display] "let val i = 3 in (i * i, "foo") end" "(9, \<dots>)"}\<close>}+
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  +
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  to obtain+
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+
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  @{ML_resp [display] "let val i = 3 in (i * i, \"foo\") end" "(9, _)"} +
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+
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  In both cases, the check by the compiler ensures that code and result+
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  match. A limitation of this document antiquotation, however, is that the+
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  pattern can only be given for values that can be constructed. This excludes+
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  values that are abstract datatypes, like @{ML_type thm}s and @{ML_type cterm}s.+
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+
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\<close>+
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end+
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