From 73be8fb60adc4723421e73d38331f793f1d16886 Mon Sep 17 00:00:00 2001
From: Adrian Kummerlaender
Date: Sat, 14 Mar 2015 22:43:12 +0100
Subject: Implemented basic tape log printout in _Turing_ example *
 `machine::simulate` now returns a list of all tape states and corresponding
 head positions * rewrote some of the actual print logic in terms
 _TypeAsValue_

---
 example/turing/src/machine.h | 34 ++++++++++++++++------------
 example/turing/turing.cc     | 53 ++++++++++++++++++++++++++------------------
 2 files changed, 52 insertions(+), 35 deletions(-)

diff --git a/example/turing/src/machine.h b/example/turing/src/machine.h
index a30c6e3..4a72d94 100644
--- a/example/turing/src/machine.h
+++ b/example/turing/src/machine.h
@@ -63,19 +63,22 @@ class simulate {
 		>::template get<Field>;
 
 	public:
-		using type = tav::Eval<simulate<
-			Transition,
-			current_state<state::field::NEXT>,
-			tape::writeSymbol<
-				Position,
-				current_state<state::field::WRITE>,
-				Tape
-			>,
-			updatePosition<
-				current_state<state::field::MOVE>,
-				Position
-			>
-		>>;
+		using type = tav::Cons<
+			tav::Pair<Position, Tape>,
+			tav::Eval<simulate<
+				Transition,
+				current_state<state::field::NEXT>,
+				tape::writeSymbol<
+					Position,
+					current_state<state::field::WRITE>,
+					Tape
+				>,
+				updatePosition<
+					current_state<state::field::MOVE>,
+					Position
+				>
+			>>
+		>;
 };
 
 template <
@@ -84,7 +87,10 @@ template <
 	typename                           Position
 >
 struct simulate<Transition, void, Tape, Position> {
-	typedef Tape type;
+	using type = tav::Cons<
+		tav::Pair<Position, Tape>,
+		void
+	>;
 };
 
 // (define (run program state tape position)
diff --git a/example/turing/turing.cc b/example/turing/turing.cc
index 070bc16..f015e02 100644
--- a/example/turing/turing.cc
+++ b/example/turing/turing.cc
@@ -47,66 +47,77 @@ using binary_increment = tav::List<
 	tav::List<tav::Size<2>, tav::Boolean<true>,  tav::Boolean<true>,  tav::Size<2>, tav::Char<'R'>>
 >;
 
-template <
-	typename Initial,
-	typename Final
->
-void printStates(const std::string& name) {
-	const auto printField = [](const auto x) {
-		std::cout << x << ' ';
-	};
+const auto printField = [](const auto x) {
+	std::cout << x;
+};
 
-	std::cout << name
-	          << std::endl
-	          << "   Initial: ";
+template <typename States>
+void printStates() {
+	using position = tav::Car<tav::Head<States>>;
+	using tape     = tav::Cdr<tav::Head<States>>;
+	using prefix   = tav::MakeList<tav::Size<3>, tav::Char<' '>>;
 
-	tav::runtime::for_each<Initial>(printField);
+	tav::runtime::for_each<tav::Concatenate<prefix, tape>>(printField);
 
-	std::cout << std::endl
-	          << "   Final:   ";
+	std::cout << std::endl;
 
-	tav::runtime::for_each<Final>(printField);
+	tav::runtime::for_each<tav::Concatenate<
+		prefix,
+		tav::MakeList<position, tav::Char<' '>>,
+		tav::List<tav::Char<'^'>>
+	>>(printField);
 
 	std::cout << std::endl;
+
+	printStates<tav::Tail<States>>();
 }
 
+template <>
+void printStates<void>() { }
+
 int main(int, char **) {
 	// (define mirror_tape (list 1 1 1 0 0 0 0))
 	using mirror_tape = tav::ListOfType<int, 1, 1, 1, 0, 0, 0, 0>;
 
+	std::cout << "1. Mirror"
+	          << std::endl;
+
 	printStates<
-		mirror_tape,
 		machine::run<
 			mirror,
 			tav::Size<1>,
 			mirror_tape,
 			tav::Size<0>
 		>
-	>("1. Mirror");
+	>();
 
 	// (define busy_beaver_tape (make-list 13 0))
 	using busy_beaver_tape = tav::MakeList<tav::Size<13>, tav::Int<0>>;
 
+	std::cout << "2. Busy Beaver"
+	          << std::endl;
+
 	printStates<
-		busy_beaver_tape,
 		machine::run<
 			busy_beaver,
 			tav::Char<'A'>,
 			busy_beaver_tape,
 			tav::Size<6>
 		>
-	>("2. Busy Beaver");
+	>();
 
 	// (define binary_increment_tape (list #t #f #t #f #t #f))
 	using binary_increment_tape = tav::ListOfType<bool, 1, 0, 1, 0, 1, 0>;
 
+	std::cout << "3. Binary Increment"
+	          << std::endl;
+
 	printStates<
-		binary_increment_tape,
 		machine::run<
 			binary_increment,
 			tav::Size<0>,
 			binary_increment_tape,
 			tav::Size<0>
 		>
-	>("3. Binary Increment");
+	>();
 }
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