From e6aed50fe9adf505cdc2be435f51f053a11c1be1 Mon Sep 17 00:00:00 2001
From: Robert Bendun <robben@st.amu.edu.pl>
Date: Sat, 11 Jun 2022 19:00:36 +0200
Subject: [PATCH] Support for midi program change message

---
 src/interpreter.cc | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/src/interpreter.cc b/src/interpreter.cc
index 858da5f..f0a924d 100644
--- a/src/interpreter.cc
+++ b/src/interpreter.cc
@@ -432,6 +432,32 @@ Interpreter::Interpreter()
 			unreachable();
 		});
 
+		{
+			constexpr auto pgmchange = +[](Interpreter &i, std::vector<Value> args) -> Result<Value> {
+				using Program = Shape<Value::Type::Number>;
+				using Channel_Program = Shape<Value::Type::Number, Value::Type::Number>;
+
+				if (Program::typecheck(args)) {
+					auto [program] = Program::move_from(args);
+					i.midi_connection->send_program_change(0, program.as_int());
+					return Value{};
+				}
+
+				if (Channel_Program::typecheck(args)) {
+					auto [chan, program] = Channel_Program::move_from(args);
+					i.midi_connection->send_program_change(chan.as_int(), program.as_int());
+					return Value{};
+				}
+
+				unreachable();
+			};
+
+			global.force_define("instrument",     pgmchange);
+			global.force_define("pgmchange",      pgmchange);
+			global.force_define("program_change", pgmchange);
+		}
+
+
 		operators["+"] = plus_minus_operator<std::plus<>>;
 		operators["-"] = plus_minus_operator<std::minus<>>;
 		operators["*"] = binary_operator<std::multiplies<>>;