theory Antiquotes
imports "../Appendix"
begin
section \<open>Useful Document Antiquotations\label{rec:docantiquotations}\<close>
text \<open>
{\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
\<close>
print_antiquotations
text \<open>
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 \<open>ML_checked\<close> with the syntax:
@{text [display] \<open>@{ML_checked "a_piece_of_code"}\<close>}
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 \<open>ML_Context.eval_source_in\<close>} in Line 7 below). The complete code of the
document antiquotation is as follows:
\<close>
ML \<open>Input.pos_of\<close>
ML%linenosgray\<open>fun ml_enclose bg en source =
ML_Lex.read bg @ ML_Lex.read_source false source @ ML_Lex.read en;\<close>
ML%linenosgray\<open>fun ml_val code_txt = (ml_enclose "val _ = " "" code_txt)
fun output_ml ctxt code_txt =
let
val _ = ML_Context.eval_in (SOME ctxt) ML_Compiler.flags (Input.pos_of code_txt) (ml_val code_txt)
in
Pretty.str (Input.source_content code_txt)
end
val ml_checked_setup = Thy_Output.antiquotation_pretty_source @{binding "ML_checked"} (Scan.lift Args.text_input) output_ml\<close>
setup \<open>ml_checked_setup\<close>
text \<open>
The parser @{ML \<open>(Scan.lift Args.name)\<close>} 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 \<open>eval_in\<close> in ML_Context}, which calls the compiler. If the code is
``approved'' by the compiler, then the output function @{ML \<open>output\<close> in
Document_Antiquotation} 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 \<open>(space_explode "\\n" txt)\<close>
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 \<open>output\<close> in Document_Antiquotation} when printing the code (including \<open>[display]\<close>
and \<open>[quotes]\<close>). The function @{ML \<open>antiquotation_raw\<close> 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 \<open>Position.none\<close>}, 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
\<close>
(* FIXME: remove
ML%linenosgray{*fun output_ml ctxt (code_txt, pos) =
let
val srcpos = {delimited = false, pos = pos, text = ml_val code_txt}
in
(ML_Context.eval_source_in (SOME ctxt) ML_Compiler.flags srcpos;
code_txt
|> space_explode "\n"
|> map Pretty.str
|> Pretty.list "" ""
|> Document_Antiquotation.output ctxt
|> Latex.string)
end
val ml_checked_setup2 = Thy_Output.antiquotation @{binding "ML_checked2"}
(Scan.lift (Parse.position Args.name)) output_ml *}
setup {* ml_checked_setup2 *}
*)
text \<open>
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 \<open>@{ML_checked2 "2 + 3"}\<close> in a document in order to
obtain @{ML_checked "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] \<open>@{ML_resp "a_piece_of_code" "a_pattern"}\<close>}
To add some convenience and also to deal with large outputs, the user can
give a partial specification by using ellipses. For example \<open>(\<dots>, \<dots>)\<close>
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 \<open>ML_checked2\<close> we sent the expression @{text [quotes]
"val _ = a_piece_of_code"} to the compiler; now the wildcard \<open>_\<close>
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:
\<close>
ML%linenosgray\<open>fun ml_pat pat code =
ML_Lex.read "val" @ ML_Lex.read_source false pat @ ML_Lex.read " = " @ ML_Lex.read_source false code\<close>
(*
ML %grayML{*fun ml_pat code_txt pat =
let val pat' =
implode (map (fn "\<dots>" => "_" | s => s) (Symbol.explode pat))
in
ml_enclose ("val " ^ pat' ^ " = ") "" code_txt
end*}
*)
text \<open>
Next we add a response indicator to the result using:
\<close>
ML %grayML\<open>fun add_resp pat = map (fn s => "> " ^ s) pat\<close>
text \<open>
The rest of the code of \<open>ML_resp\<close> is:
\<close>
ML %linenosgray\<open>
fun output_ml_resp ctxt (code_txt, pat) =
let
val _ = ML_Context.eval_in (SOME ctxt) ML_Compiler.flags (Input.pos_of code_txt) (ml_pat pat code_txt)
val code = space_explode "\n" (Input.source_content code_txt)
val resp = add_resp (space_explode "\n" (Input.source_content pat))
in
Pretty.str (cat_lines (code @ resp))
end
val ml_response_setup = Thy_Output.antiquotation_pretty_source @{binding "ML_resp"} (Scan.lift (Args.text_input -- Args.text_input)) output_ml_resp
\<close>
(*
ML %linenosgray{*fun output_ml_resp {context = ctxt, ...} ((code_txt, pat), pos) =
(let
val srcpos = {delimited = false, text = ml_pat (code_txt, pat), pos = pos}
in
ML_Context.eval_source_in (SOME ctxt) ML_Compiler.flags srcpos
end;
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.text_input -- Args.text_input)))
output_ml_resp*}
*)
setup \<open>ml_response_setup\<close>
(* FIXME *)
text \<open>
In comparison with \<open>ML_checked\<close>, 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] \<open>@{ML_resp [display] "true andalso false" "false"}\<close>}
to obtain
@{ML_resp [display] "true andalso false" "false"}
or
@{text [display] \<open>@{ML_resp [display] "let val i = 3 in (i * i, "foo") end" "(9, \<dots>)"}\<close>}
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.
\<close>
end