I have been trying to build a type system with the Hindley-Milner Algorithm and ran into the following challenge and was curious if there are any resources or papers out there I can take a look at.
Suppose I have a programming language that has some form of property accessor (javascript-like) that works for both arrays and objects, s.t. the property within the brackets for an array needs to be a number and the property within the brackets for an object needs to be a string.
For example
const arr = [0, 1, 2]
arr[0]
const obj = { hello: "World" }
obj["hello"]
Suppose we want to use hindley-milner on the following code snippet
A[B]
Then if later we realized that B is a number, then we instantly deduce that A is an array. Similarly, if we deduce that A is an object, then B is instantly a number.
Are there any papers or type systems out there that have this sort of conditional substitution concept?