diff -r 8939b8fd8603 -r 069d525f8f1d ProgTutorial/Recipes/Antiquotes.thy --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/ProgTutorial/Recipes/Antiquotes.thy Thu Mar 19 13:28:16 2009 +0100 @@ -0,0 +1,165 @@ + +theory Antiquotes +imports "../Base" +begin + + +section {* Useful Document Antiquotations *} + +text {* + (FIXME: update to to new antiquotation setup) + + {\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. If you type @{text "Ctrl-c Ctrl-a h A"} inside ProofGeneral, you + obtain a list of all currently available document antiquotations and their options. + You obtain the same list on the ML-level by typing + + @{ML [display,gray] "ThyOutput.print_antiquotations ()"} + + Below we give the code for two additional document 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"} 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_in"} in Line 4 below). The complete code of the + document antiquotation is as follows: + +*} + +ML%linenosgray{*fun ml_val code_txt = "val _ = " ^ code_txt + +fun output_ml {context = ctxt, ...} code_txt = + (ML_Context.eval_in (SOME ctxt) false Position.none (ml_val code_txt); + ThyOutput.output (map Pretty.str (space_explode "\n" code_txt))) + +val _ = ThyOutput.antiquotation "ML_checked" (Scan.lift Args.name) output_ml*} + +text {* + The parser @{ML "(Scan.lift Args.name)"} in line 9 parses a string, in this + case the code. As mentioned before, the code is sent to the ML-compiler in + the line 4 using the function @{ML ml_val}, which constructs the appropriate + ML-expression. If the code is ``approved'' by the compiler, then the output + function @{ML "ThyOutput.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 this list according to + linebreaks. There are a number of options for antiquotations that are + observed by @{ML ThyOutput.output} when printing the code (including @{text + "[display]"} and @{text "[quotes]"}). 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_in (SOME ctxt) false pos (ml_val code_txt); + ThyOutput.output (map Pretty.str (space_explode "\n" code_txt))) + +val _ = ThyOutput.antiquotation "ML_checked" + (Scan.lift (OuterParse.position Args.name)) output_ml *} + +text {* + where in Lines 1 and 2 the positional information is properly treated. The + parser @{ML OuterParse.position} encodes the positional information in the + result. + + 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 document antiquotation we describe extends the first by a pattern + that specifies what the result of the ML-code should be and check 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 inside the pattern by giving abbreviations of + the form @{text [quotes] "\"}. For example @{text "(\, \)"} for specifying a + pair. + + In the document antiquotation @{text "@{ML_checked \"piece_of_code\"}"} + above we have sent the expression @{text [quotes] "val _ = piece_of_code"} + to the compiler, now instead the wildcard @{text "_"} we will be replaced by + the given pattern. To do this we need to replace in the input the @{text + [quotes] "\"} by @{text [quotes] "_"} before sending the code to the + compiler. The following function will do this: +*} + +ML{*fun ml_pat (code_txt, pat) = +let val pat' = + implode (map (fn "\" => "_" | s => s) (Symbol.explode pat)) +in + "val " ^ pat' ^ " = " ^ code_txt +end*} + +text {* + Next we like to add a response indicator to the result using: +*} + + +ML{*fun add_resp pat = map (fn s => "> " ^ s) pat*} + +text {* + The rest of the code of the document antiquotation is +*} + +ML{*fun output_ml_resp {context = ctxt, ...} ((code_txt, pat), pos) = + (ML_Context.eval_in (SOME ctxt) false pos (ml_pat (code_txt, pat)); + let + val output1 = space_explode "\n" code_txt + val output2 = add_resp (space_explode "\n" pat) + in + ThyOutput.output (map Pretty.str (output1 @ output2)) + end) + +val _ = ThyOutput.antiquotation "ML_resp" + (Scan.lift (OuterParse.position (Args.name -- Args.name))) + output_ml_resp*} + +text {* + This extended document antiquotation allows us to 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, \)\"}"} + + to obtain + + @{ML_resp [display] "let val i = 3 in (i * i, \"foo\") end" "(9, \)"} + + 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 \ No newline at end of file