create bft package and dir, use char instead of dchar where possible

source/app.d

@@ -1,4 +1,4 @@
-import bf;
+import bft;
 void main() {
 	auto program = BFProgram!(import("mandel.b"))();
 	program.execute();

source/bf.d → source/bft/bf.d

@@ -1,30 +1,41 @@
-import std.range : isInputRange, isOutputRange;
+///A brainfuck implementation that uses transpiling to produce native machine code.
+module bft.bf;
+
+import std.range : ElementType, isInputRange, isOutputRange;
+import std.traits : isSomeString;
+struct StdInput {
+	import std.stdio : stdin;
+	char lastRead;
+	bool empty() { return stdin.isOpen; }
+	char front() { return lastRead; }
+	void popFront() { if (stdin.rawRead([lastRead]).length == 0) stdin.close(); }
+}
 ///A brainfuck program
 struct BFProgram(string program, size_t memSize = 8192) {
 	///Just a big ol' block of memory
-	dchar[memSize] memory = void;
+	char[memSize] memory = void;
 	///Program data pointer
 	size_t ptr = 0;
 
 	///Compile and execute program
 	void execute() {
-		import std.stdio : stdin, stdout;
-		struct StdInput {
-			char lastRead;
-			bool empty() { return stdin.isOpen; }
-			char front() { return lastRead; }
-			void popFront() { if (stdin.rawRead([lastRead]).length == 0) stdin.close(); }
-		}
+		import std.stdio : stdout;
 		auto inp = StdInput();
 		auto outp = stdout.lockingTextWriter;
 		execute(inp, outp);
 	}
-	void execute(Input, Output)(Input stdin, Output stdout) if (isInputRange!Input && isOutputRange!(Output, char)) {
-		import std.range : put, front, popFront, empty;
+	///ditto
+	void execute(Input, Output)(Input stdin, Output stdout) if (isInputRange!Input && !isSomeString!Input && is(ElementType!Input : char) && isOutputRange!(Output, char)) {
+		import std.range : put;
 		import std.algorithm : copy;
 		memory[] = '\0';
 		mixin(transpile(program));
 	}
+	///ditto
+	void execute(Input, Output)(Input stdin, Output stdout) if (isSomeString!Input && isOutputRange!(Output, char)) {
+		import std.utf : byCodeUnit;
+		execute(stdin.byCodeUnit, stdout);
+	}
 }
 ///Transpile bf -> D
 string transpile(string program) pure @safe {
@@ -64,20 +75,19 @@ string transpile(string program) pure @safe {
 	}
 	return prog.join("\n");
 }
+///
 unittest {
 	import std.array : appender;
 	{
 		auto program = BFProgram!(import("helloworld.b"), 7)();
 		auto outbuf = appender!(char[])();
-		char[] inbuf;
-		program.execute(inbuf, outbuf);
+		program.execute("", outbuf);
 		assert(outbuf.data == "Hello World!\n");
 	}
 	{
 		auto program = BFProgram!(import("bench.b"), 8)();
 		auto outbuf = appender!(char[])();
-		char[] inbuf;
-		program.execute(inbuf, outbuf);
+		program.execute("", outbuf);
 		assert(outbuf.data == "ZYXWVUTSRQPONMLKJIHGFEDCBA\n");
 	}
 	{
@@ -94,8 +104,7 @@ unittest {
 		import std.utf : toUTF8;
 		auto program = BFProgram!(import("392quine.b"), 1024)();
 		auto outbuf = appender!(char[])();
-		char[] inbuf;
-		program.execute(inbuf, outbuf);
+		program.execute("", outbuf);
 		assert(outbuf.data == import("392quine.b").splitter("\x1A").front.filter!(x => !x.isWhite).array.toUTF8~"\x1A");
 	}
 }

source/bft/package.d

@@ -0,0 +1,3 @@
+module bft;
+
+public import bft.bf;