#6 Number subtypes

lib/checker.js

@@ -1190,7 +1190,7 @@ function handleAssignmentExpressionType(scope,exprNode,targetNode,sourceNode,isA
 				}
 				// target already has an implied type?
 				if (targetType) {
-					if (!typesMatch(sourceType,targetType)) {
+					if (!isAssignmentAllowed(targetType,sourceType)) {
 						if (targetType.inferred == "undef") {
 							delete targetType.inferred;
 							Object.assign(targetType,sourceType);
@@ -1673,6 +1673,23 @@ function typesMatch(type1,type2) {
 	);
 }
 
+function isAssignmentAllowed(type1, type2){
+	if(typesMatch(type1, type2)){
+		return true;
+	}
+
+	let matches = {
+		int: ["int"],
+		number: ["number", "int", "finite"],
+		finite: ["finite", "int"],
+		bint: ["bint", "int"]
+	}
+	let type1ID = getTypeID(type1) 
+	let type2ID = getTypeID(type2) 
+
+	return matches[type1ID] && matches[type1ID].includes(type2ID)
+}
+
 function isNumberOrSubtype(type) {
 	var typeID = getTypeID(type);
 	return (typeID == "number" || isFiniteOrSubtype(typeID));