initial ideas

femto-lang/faux/trying.js

@@ -0,0 +1,141 @@
+const STR = (s) => ({type: "string", value: s});
+const FN = (f) => ({type: "function", value: f});
+const SYM = (s) => ({type: "symbol", value: s});
+const UNDEF = () => ({type: "undefined", value: null});
+const CODE = (p) => ({type: "code", value: p});
+const THUNK = (t) => ({type: "thunk", value: t});
+const BOOL = (b) => ({type: "boolean", value: b});
+
+const evaluate_codeblock = (codeBlock, env) => {
+	let result = {
+		result: UNDEF(),
+		passalong: {},
+	};
+	const terms = [...codeBlock.value];
+	while (terms.length) {
+		// console.log('evaluating phrase', terms);
+		result = evaluate_phrase(terms, env, result.passalong);
+	}
+	return result;
+}
+
+const evaluate_phrase = (terms, env, passalong) => {
+	let head = evaluate_term(terms.shift(), env, passalong);
+	let pa = passalong;
+	while (head.result.type === "function") {
+		if (!terms.length) {
+			throw 'Runtime Error: head function has no argument to be called with';
+		}
+		const tail = evaluate_term(terms.shift(), env, {});
+		head = head.result.value(tail.result, env, pa);
+		pa = head.passalong;
+	}
+	return head;
+}
+
+const evaluate_term = (term, env, passalong) => {
+	if (term.type === "symbol") {
+		return {
+			result: env[term.value],
+			passalong: {name: STR(term.value)}, // TODO: this should include term.value as a "name"
+		}
+	} else if (term.type === "string") {
+		return {
+			result: term,
+			passalong: {},
+		}
+	} else if (term.type === "function") {
+		return {
+			result: term,
+			passalong: {},
+		}
+	} else if (term.type === "boolean") {
+		return {
+			result: term,
+			passalong: {},
+		}
+	} else if (term.type === "thunk") {
+		return {
+			result: term,
+			passalong: {},
+		}
+	}
+	return {
+		result: UNDEF(),
+		passalong: {},
+	}
+}
+
+const my_env = {
+	print: FN((arg, env, passalong) => {
+		console.log('PRINT', arg);
+		return {
+			result: UNDEF(),
+			passalong: {},
+		}
+	}),
+	if: FN((arg, env, passalong) => {
+		return {
+			result: FN((thunk, e2, pa) => {
+				if (arg.type === "boolean" && arg.value) {
+					return {
+						result: evaluate_codeblock(thunk, e2),
+						passalong: {handled: true},
+					}
+				} else {
+					return {
+						result: UNDEF(),
+						passalong: {handled: false},
+					}
+				}
+			}),
+			passalong: {},
+		}
+	}),
+	else: FN((thunk, env, passalong) => {
+		if (!passalong.handled) {
+			return {
+				result: evaluate_codeblock(thunk, env),
+				passalong: {handled: true},
+			}
+		} else {
+			return {
+				result: UNDEF(),
+				passalong: {handled: true},
+			}
+		}
+	}),
+}
+
+`
+print "hi"
+if false {
+	print "hi2"
+} else {
+	print "hi3"
+}
+set x = 10
+set y = 20
+set f = fn h => {
+	print h
+	print h
+}
+f x
+
+for value in obj {
+
+}
+`
+
+
+const my_prog = CODE([
+	SYM("print"), STR("hi"),
+	SYM("if"), BOOL(false), THUNK([
+		SYM("print"), STR("hi2"),
+	]),
+	SYM("else"), THUNK([
+		SYM("print"), STR("hi3"),
+	]),
+]);
+
+console.log(evaluate_codeblock(my_prog, my_env));