theory Antiquotesimports "../Appendix"beginsection {* Useful Document Antiquotations\label{rec:docantiquotations} *}text {* {\bf Problem:} How to keep your ML-code inside a document synchronised with the actual code?\smallskip {\bf Solution:} This can be achieved with 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. If you type on the Isabelle level*}print_antiquotationstext {* you obtain a list of all currently available document antiquotations and their options. Below we will give the code for two additional document antiquotations both of which are intended to typeset ML-code. The crucial point of these document antiquotations is that they not just print the ML-code, but also check whether it compiles. This will provide a sanity check for the code and also allows you to keep documents in sync with other code, for example Isabelle. We first describe the antiquotation @{text "ML_checked"} with the syntax: @{text [display] "@{ML_checked \"a_piece_of_code\"}"} The code is checked by sending the ML-expression @{text [quotes] "val _ = a_piece_of_code"} to the ML-compiler (i.e.~the function @{ML "ML_Context.eval_text_in"} in Line 4 below). The complete code of the document antiquotation is as follows:*}ML%linenosgray{*fun ml_val code_txt = "val _ = " ^ code_txtfun output_ml {context = ctxt, ...} code_txt = (ML_Context.eval_text_in (SOME ctxt) false Position.none (ml_val code_txt); Thy_Output.output ctxt (map Pretty.str (space_explode "\n" code_txt)))val ml_checked_setup = Thy_Output.antiquotation @{binding "ML_checked"} (Scan.lift Args.name) output_ml*}setup {* ml_checked_setup *}text {* The parser @{ML "(Scan.lift Args.name)"} in Line 7 parses a string, in this case the code, and then calls the function @{ML output_ml}. As mentioned before, the parsed code is sent to the ML-compiler in Line 4 using the function @{ML ml_val}, which constructs the appropriate ML-expression, and using @{ML "eval_in" in ML_Context}, which calls the compiler. If the code is ``approved'' by the compiler, then the output function @{ML "output" in Thy_Output} in the next line pretty prints the code. This function expects that the code is a list of (pretty)strings where each string correspond to a line in the output. Therefore the use of @{ML "(space_explode \"\\n\" txt)" for txt} which produces such a list according to linebreaks. There are a number of options for antiquotations that are observed by the function @{ML "output" in Thy_Output} when printing the code (including @{text "[display]"} and @{text "[quotes]"}). The function @{ML "antiquotation" in Thy_Output} in Line 7 sets up the new document antiquotation. \begin{readmore} For more information about options of document antiquotations see \rsccite{sec:antiq}). \end{readmore} Since we used the argument @{ML "Position.none"}, the compiler cannot give specific information about the line number, in case an error is detected. We can improve the code above slightly by writing *}ML%linenosgray{*fun output_ml {context = ctxt, ...} (code_txt, pos) = (ML_Context.eval_text_in (SOME ctxt) false pos (ml_val code_txt); Thy_Output.output ctxt (map Pretty.str (space_explode "\n" code_txt)))val ml_checked_setup2 = Thy_Output.antiquotation @{binding "ML_checked2"} (Scan.lift (Parse.position Args.name)) output_ml *}setup {* ml_checked_setup2 *}text {* where in Lines 1 and 2 the positional information is properly treated. The parser @{ML Parse.position} encodes the positional information in the result. We can now write @{text "@{ML_checked2 \"2 + 3\"}"} in a document in order to obtain @{ML_checked2 "2 + 3"} and be sure that this code compiles until somebody changes the definition of addition. The second document antiquotation we describe extends the first by a pattern that specifies what the result of the ML-code should be and checks the consistency of the actual result with the given pattern. For this we are going to implement the document antiquotation: @{text [display] "@{ML_resp \"a_piece_of_code\" \"a_pattern\"}"} To add some convenience and also to deal with large outputs, the user can give a partial specification by using ellipses. For example @{text "(\<dots>, \<dots>)"} for specifying a pair. In order to check consistency between the pattern and the output of the code, we have to change the ML-expression that is sent to the compiler: in @{text "ML_checked2"} we sent the expression @{text [quotes] "val _ = a_piece_of_code"} to the compiler; now the wildcard @{text "_"} must be be replaced by the given pattern. However, we have to remove all ellipses from it and replace them by @{text [quotes] "_"}. The following function will do this:*}ML %grayML{*fun ml_pat (code_txt, pat) =let val pat' = implode (map (fn "\<dots>" => "_" | s => s) (Symbol.explode pat))in "val " ^ pat' ^ " = " ^ code_txt end*}text {* Next we add a response indicator to the result using:*}ML %grayML{*fun add_resp pat = map (fn s => "> " ^ s) pat*}text {* The rest of the code of @{text "ML_resp"} is: *}ML %linenosgray{*fun output_ml_resp {context = ctxt, ...} ((code_txt, pat), pos) = (ML_Context.eval_text_in (SOME ctxt) false pos (ml_pat (code_txt, pat)); let val code_output = space_explode "\n" code_txt val resp_output = add_resp (space_explode "\n" pat) in Thy_Output.output ctxt (map Pretty.str (code_output @ resp_output)) end)val ml_resp_setup = Thy_Output.antiquotation @{binding "ML_resp"} (Scan.lift (Parse.position (Args.name -- Args.name))) output_ml_resp*}setup {* ml_resp_setup *}text {* In comparison with @{text "ML_checked2"}, we only changed the line about the compiler (Line~2), the lines about the output (Lines 4 to 7) and the parser in the setup (Line 11). Now you can write @{text [display] "@{ML_resp [display] \"true andalso false\" \"false\"}"} to obtain @{ML_resp [display] "true andalso false" "false"} or @{text [display] "@{ML_resp [display] \"let val i = 3 in (i * i, \"foo\") end\" \"(9, \<dots>)\"}"} to obtain @{ML_resp [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 document antiquotation, however, is that the pattern can only be given for values that can be constructed. This excludes values that are abstract datatypes, like @{ML_type thm}s and @{ML_type cterm}s.*}end