1 

     2 theory Antiquotes

     3 imports "../Base"

     4 begin

     5 

     6 

     7 section {* Useful Document Antiquotations *}

     8 

     9 text {*

    10   (FIXME: update to to new antiquotation setup)

    11 

    12   {\bf Problem:} 

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

    14 

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

    16 

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

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

    19   \LaTeX-hacking. If you type @{text "Ctrl-c Ctrl-a h A"} inside ProofGeneral, you

    20   obtain a list of all currently available document antiquotations and their options.

    21   You obtain the same list on the ML-level by typing

    22 

    23   @{ML [display,gray] "ThyOutput.print_antiquotations ()"}

    24 

    25   Below we give the code for two additional document antiquotations that can

    26   be used to typeset ML-code and also to check whether the given code actually

    27   compiles. This provides a sanity check for the code and also allows one to

    28   keep documents in sync with other code, for example Isabelle.

    29 

    30   We first describe the antiquotation @{text "ML_checked"} with the syntax:

    31  

    32   @{text [display] "@{ML_checked \"a_piece_of_code\"}"}

    33 

    34   The code is checked by sending the ML-expression @{text [quotes] "val _ =

    35   a_piece_of_code"} to the ML-compiler (i.e.~the function @{ML

    36   "ML_Context.eval_in"} in Line 4 below). The complete code of the

    37   document antiquotation is as follows:

    38 

    39 *}

    40 

    41 ML%linenosgray{*fun ml_val code_txt = "val _ = " ^ code_txt

    42 

    43 fun output_ml {context = ctxt, ...} code_txt =

    44   (ML_Context.eval_in (SOME ctxt) false Position.none (ml_val code_txt); 

    45    ThyOutput.output (map Pretty.str (space_explode "\n" code_txt)))

    46 

    47 val _ = ThyOutput.antiquotation "ML_checked" (Scan.lift Args.name) output_ml*}

    48 

    49 text {*

    50   The parser @{ML "(Scan.lift Args.name)"} in line 9 parses a string, in this

    51   case the code. As mentioned before, the code is sent to the ML-compiler in

    52   the line 4 using the function @{ML ml_val}, which constructs the appropriate

    53   ML-expression.  If the code is ``approved'' by the compiler, then the output

    54   function @{ML "ThyOutput.output"} in the next line pretty prints the

    55   code. This function expects that the code is a list of (pretty)strings where

    56   each string correspond to a line in the output. Therefore the use of @{ML

    57   "(space_explode \"\\n\" txt)" for txt} which produces this list according to

    58   linebreaks.  There are a number of options for antiquotations that are

    59   observed by @{ML ThyOutput.output} when printing the code (including @{text

    60   "[display]"} and @{text "[quotes]"}). Line 7 sets up the new document

    61   antiquotation.

    62 

    63 

    64   \begin{readmore}

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

    66   \end{readmore}

    67 

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

    69   information about the line number, in case an error is detected. We 

    70   can improve the code above slightly by writing 

    71 *}

    72 

    73 ML%linenosgray{*fun output_ml {context = ctxt, ...} (code_txt, pos) =

    74   (ML_Context.eval_in (SOME ctxt) false pos (ml_val code_txt);

    75    ThyOutput.output (map Pretty.str (space_explode "\n" code_txt)))

    76 

    77 val _ = ThyOutput.antiquotation "ML_checked"

    78          (Scan.lift (OuterParse.position Args.name)) output_ml *}

    79 

    80 text {*

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

    82   parser @{ML OuterParse.position} encodes the positional information in the 

    83   result.

    84 

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

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

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

    88 

    89 

    90   The second document antiquotation we describe extends the first by a pattern

    91   that specifies what the result of the ML-code should be and check the

    92   consistency of the actual result with the given pattern. For this we are

    93   going to implement the document antiquotation

    94 

    95   

    96   @{text [display] "@{ML_resp \"a_piece_of_code\" \"a_pattern\"}"}

    97   

    98   To add some convenience and also to deal with large outputs, the user can

    99   give a partial specification inside the pattern by giving abbreviations of

   100   the form @{text [quotes] "\<dots>"}. For example @{text "(\<dots>, \<dots>)"} for specifying a

   101   pair.

   102 

   103   In the document antiquotation @{text "@{ML_checked \"piece_of_code\"}"}

   104   above we have sent the expression @{text [quotes] "val _ = piece_of_code"}

   105   to the compiler, now instead the wildcard @{text "_"} we will be replaced by

   106   the given pattern. To do this we need to replace in the input the @{text

   107   [quotes] "\<dots>"} by @{text [quotes] "_"} before sending the code to the

   108   compiler. The following function will do this:

   109 *}

   110 

   111 ML{*fun ml_pat (code_txt, pat) =

   112 let val pat' = 

   113          implode (map (fn "\<dots>" => "_" | s => s) (Symbol.explode pat))

   114 in 

   115   "val " ^ pat' ^ " = " ^ code_txt 

   116 end*}

   117 

   118 text {* 

   119   Next we like to add a response indicator to the result using:

   120 *}

   121 

   122 

   123 ML{*fun add_resp pat = map (fn s => "> " ^ s) pat*}

   124 

   125 text {* 

   126   The rest of the code of the document antiquotation is

   127 *}

   128 

   129 ML{*fun output_ml_resp {context = ctxt, ...} ((code_txt, pat), pos) = 

   130   (ML_Context.eval_in (SOME ctxt) false pos (ml_pat (code_txt, pat));

   131    let 

   132      val output1 = space_explode "\n" code_txt 

   133      val output2 = add_resp (space_explode "\n" pat)

   134    in 

   135      ThyOutput.output (map Pretty.str (output1 @ output2)) 

   136    end)

   137 

   138 val _ = ThyOutput.antiquotation "ML_resp" 

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

   140            output_ml_resp*}

   141 

   142 text {*

   143   This extended document antiquotation allows us to write

   144  

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

   146 

   147   to obtain

   148 

   149   @{ML_resp [display] "true andalso false" "false"} 

   150 

   151   or 

   152 

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

   154   

   155   to obtain

   156 

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

   158 

   159   In both cases, the check by the compiler ensures that code and result

   160   match. A limitation of this document antiquotation, however, is that the

   161   pattern can only be given for values that can be constructed. This excludes

   162   values that are abstract datatypes, like @{ML_type thm}s and @{ML_type cterm}s.

   163 

   164 *}

   165 end