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Union types!! If everything’s a type and nothing works together, start wrapping them in interfaces and define an über type that unions everything everywhere all

Union types!! If everything’s a type and nothing works together, start wrapping them in interfaces and define an über type that unions everything everywhere all at once. Welcome to typescript. Where generics are at the heart of our generic generics that throw generics of some generic generic geriatric generic that Bob wrote 8 years ago. Because they can’t reason with the architecture they built, they throw it at the type system to keep them in line. It works most of the time. Rust’s is beautiful at barking at you that you’re wrong. Ultimately it’s us failing to design flexibility amongst ever increasing complexity. Remember when “Components” where “Controls” and you only had like a dozen of them? Remember when a NN was only a few hundred thousand parameters? As complexity increases with computing power, so must our understanding of it in our mental model. However you need to keep that mental model in check, use it. If it’s typing, do it. If it’s rigorous testing, write your tests. If it’s simulation, run it my friend. Ultimately, we all want better quality software that doesn’t break in unexpected ways.

valenterry 1y ago
union types are great. But alone they are not sufficient for many cases. For example, try to define a datastructure that captures a classical evaluation-tree. You might go with: type Expression = Value | Plus | Minus | Multiply | Divide; interface Value { type: "value"; value: number; } interface Plus { type: "plus"; left: Expression; right: Expression; } interface Minus { type: "minus"; left: Expression; right: Expression; } interface Multiply { type: "multiply"; left: Expression; right: Expression; } interface Divide { type: "divide"; left: Expression; right: Expression; } And so on. That looks nice, but when you try to pattern match on it and have your pattern matching return the types that are associated with the specific operation, it won't work. The reason is that Typescript does not natively support GADTs. Libs like ts-pattern use some tricks to get closish at least. And while this might not be very important for most application developers, it is very important for library authors, especially to make libraries interoperable with each other and extend them safely and typesafe.

valenterry 1y ago

union types are great. But alone they are not sufficient for many cases. For example, try to define a datastructure that captures a classical evaluation-tree. You might go with: type Expression = Value | Plus | Minus | Multiply | Divide; interface Value { type: "value"; value: number; } interface Plus { type: "plus"; left: Expression; right: Expression; } interface Minus { type: "minus"; left: Expression; right: Expression; } interface Multiply { type: "multiply"; left: Expression; right: Expression; } interface Divide { type: "divide"; left: Expression; right: Expression; } And so on. That looks nice, but when you try to pattern match on it and have your pattern matching return the types that are associated with the specific operation, it won't work. The reason is that Typescript does not natively support GADTs. Libs like ts-pattern use some tricks to get closish at least. And while this might not be very important for most application developers, it is very important for library authors, especially to make libraries interoperable with each other and extend them safely and typesafe.