complete compilation.

also rename misleading names "execution" to "compilation".

src/compile.mjs

@@ -0,0 +1,113 @@
+import Line from "./Line.mjs";
+import Expr from "./Expr.mjs";
+
+
+
+export function compile (program) {
+	let env = new Map();
+
+	for (const line of program) {
+		const result = compile_line(env, line);
+
+		if (!result.valid) {
+			return {
+				valid: false,
+				env: env,
+			};
+		}
+
+		env = result.env;
+	}
+
+	return {
+		valid: true,
+		env: env,
+	};
+}
+
+function compile_line (env, line) {
+	function invalid (current_env = env) {
+		return {
+			valid: false,
+			env: current_env,
+		};
+	}
+
+	if (line.type === Line.Invalid) return invalid();
+
+	if (line.type === Line.Empty || line.type === Line.Comment) {
+		return {
+			valid: true,
+			env: env,
+		};
+	}
+
+	if (line.type === Line.Special) {
+		// as there are currently no reserved special lines,
+		// and this implementation adds no custom ones,
+		// every special line is invalid.
+		return invalid();
+	}
+
+	if (line.type === Line.Binding) {
+		let value;
+		let valid = true;
+
+		try {
+			value = evaluate(env, line.body);
+		} catch (e) {
+			valid = false;
+		}
+
+		if (!valid) return invalid();
+
+		const new_env = new Map(env);
+		new_env.set(line.name, value);
+
+		return {
+			valid: true,
+			env: new_env,
+		};
+	}
+
+	return invalid();
+}
+
+function evaluate (env, expr, locals = []) {
+	if (expr.type === Expr.Token) {
+		const token = expr.value;
+
+		if (has_local(locals, token)) {
+			return get_local(locals, token);
+		}
+
+		if (env.has(token)) {
+			return env.get(token);
+		}
+
+		throw new Error();
+	}
+
+	if (expr.type === Expr.Application) {
+		const fn = evaluate(env, expr.fn, locals);
+		const arg = evaluate(env, expr.arg, locals);
+		return([fn, arg]);
+	}
+
+	if (expr.type === Expr.Fn) {
+		const args = [ ...expr.args ].reverse();
+		const body = evaluate(env, expr.body, args);
+
+		return body;
+	}
+
+	throw new Error();
+}
+
+function has_local (locals, name) {
+	return locals.includes(name);
+}
+
+function get_local (locals, name) {
+	return locals.indexOf(name);
+}

src/execute.mjs

@@ -1,66 +0,0 @@
-import Line from "./Line.mjs";
-
-
-
-export function execute (program) {
-	let env = new Map();
-
-	for (const line of program) {
-		const result = execute_line(env, line);
-
-		if (!result.valid) {
-			return {
-				valid: false,
-				env: env,
-			};
-		}
-
-		env = result.env;
-	}
-
-	return {
-		valid: true,
-		env: env,
-	};
-}
-
-function execute_line (env, line) {
-	function invalid () {
-		return {
-			valid: false,
-			env: env,
-		};
-	}
-
-	if (line.type === Line.Invalid) return invalid();
-
-	if (line.type === Line.Empty || line.type === Line.Comment) {
-		return {
-			valid: true,
-			env: env,
-		};
-	}
-
-	if (line.type === Line.Special) {
-		// as there are currently no reserved special lines,
-		// and this implementation adds no custom ones,
-		// every special line is invalid.
-		return invalid();
-	}
-
-	if (line.type === Line.Binding) {
-		const new_env = new Map(env);
-		new_env.set(line.name, evaluate(env, line.body));
-
-		return {
-			valid: true,
-			env: new_env,
-		};
-	}
-
-	return invalid();
-}
-
-function evaluate (env, expr) {
-	return expr;
-}