So, I want my language to have union types, because they are really convenient for storing data of different types in one variable. - I'd go as far to say that it's the most elegant solution a strongly-typed language could have for such a problem.
So, how do they work?
Well, I've based my idea on TypeScript's union-types... for the most part.
As a refresher, here is how you create and use union types.
type QResponse = number|string;
function answer_question(ans:QResponse):void {
if(typeof ans === "string")
console.log(`Responded with string: "${ans}"`);
else console.log(`Responded with number: "${ans}"`);
}
But, Janky will be a statically typed language, and won't have room for such a silly concept such as typeof.
Well, to get around this, to do anything useful with a value of type TX|TY, you must pass it to a function that has overloads for all types.
For example, if you have byte|BitSet<1>, and you want to pass it to a function f, there must be at least two overloads for f, f(byte) <return-type> and f(BitSet<8>) <return-type>.
Here's an expanded version:
type DiscrimType = unsigned int|string;
User find_user(unsigned int user_id) {
// Code...
}
User find_user(string user_tag) {
// Code...
}
User get_user(string user_tag) { /* Code... */ }
User fetch_user(DiscrimType dsc) { /* Code... */ }
User retrieve_user(DiscrimType dsc) { /* Code... */ }
User retrieve_user(string s) { /* ... */ }
User retrieve_user(unsigned long ul) { /* ... */ }
// If Janky ever has a compiler, this would
// not compile.
// If Janky is interpreted, at runtime,
// an error (`AmbiguityError`) is thrown.
DiscrimType discriminator = getDescriminator();
find_user(discriminator);
// Works.
get_user(discriminator);
// Does not work.
// It is not "promised" that `discriminator` is
// a `string`.
fetch_user(discriminator);
// Has to pass `discriminator`'s
// value to another function.
retrieve_user(145959);
// AmbiguityError: unsigned long or
// DiscrimType:[unsigned long]|number?
Any and all feedback, positive, negative, neutral, and questions are appreciated.
Cheers!
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