src/HOL/ex/ML.thy

 begin
 
 section \<open>ML expressions\<close>
 
 text \<open>
-  The Isabelle command 'ML' allows to embed Isabelle/ML source into the formal
-  text. It is type-checked, compiled, and run within that environment.
+  The Isabelle command \<^theory_text>\<open>ML\<close> allows to embed Isabelle/ML source into the
+  formal text. It is type-checked, compiled, and run within that environment.
 
   Note that side-effects should be avoided, unless the intention is to change
   global parameters of the run-time environment (rare).
 
   ML top-level bindings are managed within the theory context.

 ML \<open>val c = a + b\<close>
 
 
 section \<open>Antiquotations\<close>
 
-text \<open>There are some language extensions (via antiquotations), as explained in
-  the ``Isabelle/Isar implementation manual'', chapter 0.\<close>
+text \<open>
+  There are some language extensions (via antiquotations), as explained in the
+  ``Isabelle/Isar implementation manual'', chapter 0.
+\<close>
 
 ML \<open>length []\<close>
 ML \<open>@{assert} (length [] = 0)\<close>
 
 
 text \<open>Formal entities from the surrounding context may be referenced as
   follows:\<close>
 
-term "1 + 1"   -- \<open>term within theory source\<close>
+term "1 + 1"   \<comment> \<open>term within theory source\<close>
 
 ML \<open>@{term "1 + 1"}   (* term as symbolic ML datatype value *)\<close>
 
 ML \<open>@{term "1 + (1::int)"}\<close>
 
 
+ML \<open>
+  (* formal source with position information *)
+  val s = \<open>1 + 1\<close>;
+
+  (* read term via old-style string interface *)
+  val t = Syntax.read_term @{context} (Syntax.implode_input s);
+\<close>
+
 section \<open>IDE support\<close>
 
 text \<open>
   ML embedded into the Isabelle environment is connected to the Prover IDE.
   Poly/ML provides:
-  \begin{itemize}
-    \item precise positions for warnings / errors
-    \item markup for defining positions of identifiers
-    \item markup for inferred types of sub-expressions
-  \end{itemize}
+
+    \<^item> precise positions for warnings / errors
+    \<^item> markup for defining positions of identifiers
+    \<^item> markup for inferred types of sub-expressions
+    \<^item> pretty-printing of ML values with markup
+    \<^item> completion of ML names
+    \<^item> source-level debugger
 \<close>
 
 ML \<open>fn i => fn list => length list + i\<close>
 
 

 section \<open>Parallel Isabelle/ML\<close>
 
 text \<open>
   Future.fork/join/cancel manage parallel evaluation.
 
-  Note that within Isabelle theory documents, the top-level command boundary may
-  not be transgressed without special precautions. This is normally managed by
-  the system when performing parallel proof checking.\<close>
+  Note that within Isabelle theory documents, the top-level command boundary
+  may not be transgressed without special precautions. This is normally
+  managed by the system when performing parallel proof checking.
+\<close>
 
 ML \<open>
   val x = Future.fork (fn () => ackermann 3 10);
   val y = Future.fork (fn () => ackermann 3 10);
   val z = Future.join x + Future.join y
 \<close>
 
-text \<open>The @{ML_structure Par_List} module provides high-level combinators
-  for parallel list operations.\<close>
+text \<open>
+  The @{ML_structure Par_List} module provides high-level combinators for
+  parallel list operations.
+\<close>
 
 ML \<open>timeit (fn () => map (fn n => ackermann 3 n) (1 upto 10))\<close>
 ML \<open>timeit (fn () => Par_List.map (fn n => ackermann 3 n) (1 upto 10))\<close>
 
 

 fun factorial :: "nat \<Rightarrow> nat"
 where
   "factorial 0 = 1"
 | "factorial (Suc n) = Suc n * factorial n"
 
-term "factorial 4"  -- \<open>symbolic term\<close>
-value "factorial 4"  -- \<open>evaluation via ML code generation in the background\<close>
+term "factorial 4"  \<comment> \<open>symbolic term\<close>
+value "factorial 4"  \<comment> \<open>evaluation via ML code generation in the background\<close>
 
 declare [[ML_source_trace]]
-ML \<open>@{term "factorial 4"}\<close>  -- \<open>symbolic term in ML\<close>
-ML \<open>@{code "factorial"}\<close>  -- \<open>ML code from function specification\<close>
+ML \<open>@{term "factorial 4"}\<close>  \<comment> \<open>symbolic term in ML\<close>
+ML \<open>@{code "factorial"}\<close>  \<comment> \<open>ML code from function specification\<close>
 
 
 fun ackermann :: "nat \<Rightarrow> nat \<Rightarrow> nat"
 where
   "ackermann 0 n = n + 1"