5 ms·

The SQL stuff sounds cool, but Ecto is so expressive I don’t even need to resort to raw SQL like I do in other languages. Elixir typing can handle a subset of i

The SQL stuff sounds cool, but Ecto is so expressive I don’t even need to resort to raw SQL like I do in other languages. Elixir typing can handle a subset of intersection type which is rather niche, and of course handles union types which are more prevalent. Genetics and inheritance are replaced with a more permissive style of polymorphism with Elixir behaviors and are also part of the typing system. All languages have their own flavor, and their own pros and cons, and if the advanced types of Typescript work for you, then great! In my own experience, I have found Elixir and it’s typing capabilities to work well for me

Vaguely2178 3y ago
> The SQL stuff sounds cool, but Ecto is so expressive I don’t even need to resort to raw SQL like I do in other languages. The SQL example I linked to isn't something you'd use to interact with a database in production, for that you'd probably reach for an ORM like Prisma. I was just trying to demonstrate the level of type inference you can achieve with TS. Going from a pure string of SQL or JSON to a concrete type without actually executing any runtime code is pretty crazy. > Elixir typing can handle a subset of intersection type which is rather niche I personally use intersection types quite a bit. If union types are like the logical or operator, then intersection types are like the logical and operator. Being able to define a type that combines one type and another is not a niche workflow for me. > In my own experience, I have found Elixir and it’s typing capabilities to work well for me Can't argue with that! Everyone has their preferences.
- h0l0cube 3y ago
  > Going from a pure string of SQL or JSON to a concrete type without actually executing any runtime code is pretty crazy. Elixir/Erlang might already be able to do something like this with metaprogramming. It’s certainly possible to generate and run Elixir at compile time, and map types are already a good superset for JSON objects, so a compile time JSON to map could then provide an inferrable type. I think someone more savvy with Elixir would know more. I’d certainly not something that I’ve needed.
- erszcz 3y ago
  > Going from a pure string of SQL or JSON to a concrete type without actually executing any runtime code is pretty crazy. Going from a JSON string to a type for it is actually one of the easier examples of inference I can imagine. JSON is a data description format in which all the base types are syntactically distinguishable, it has no variables, no arrows (i.e. functions), no generics. In the topic of type inference, you can't have a much easier example. SQL is more complex, indeed, but still doesn't seem too crazy if you have access to table schemas. It's also a matter of whether triggers and stored procedures are taken into account, but I assume they're not. There's a lot of prior art described in literature as well as practical programming implementations with much crazier, yet successfully working type inference.
  - Vaguely2178 3y ago
    I just want to make sure we're on the same page here. The JSON example I linked to isn't inferring the types of JSON that's already been parsed and deserialized, that would be trivially easy in any language (including TS). If I have an object that's been parsed from JSON, I can just use the typeof operator in TypeScript to infer the type of that object. The example I linked to is taking a serialized JSON string, and parsing the literal characters in the string (characters like double quotes, commas, whitespace, etc) into a type, purely using type annotations. And the structure of that JSON can be of arbitrary nested depth. All of this is accomplished using template literal types which allow you to make assertions about the contents of a string. In TypeScript you can assert more than just "this value should be a string". You can make detailed assertions about the structure of strings, and that's what allows these parser demos to exist. When you combine these template literal types with recursive types, conditional types, and TypeScript's infer keyword you can do some pretty interesting type level programming. Just to further demonstrate the point, there's an interpreter for the BF programming language, written entirely using TypeScript type annotations [1]. > There's a lot of prior art described in literature as well as practical programming implementations with much crazier, yet successfully working type inference. Has any of this been demonstrated in Elixir? [1] https://github.com/sno2/bf https://github.com/sno2/bf
    - h0l0cube 3y ago

Vaguely2178 3y ago

> The SQL stuff sounds cool, but Ecto is so expressive I don’t even need to resort to raw SQL like I do in other languages. The SQL example I linked to isn't something you'd use to interact with a database in production, for that you'd probably reach for an ORM like Prisma. I was just trying to demonstrate the level of type inference you can achieve with TS. Going from a pure string of SQL or JSON to a concrete type without actually executing any runtime code is pretty crazy. > Elixir typing can handle a subset of intersection type which is rather niche I personally use intersection types quite a bit. If union types are like the logical or operator, then intersection types are like the logical and operator. Being able to define a type that combines one type and another is not a niche workflow for me. > In my own experience, I have found Elixir and it’s typing capabilities to work well for me Can't argue with that! Everyone has their preferences.

h0l0cube 3y ago
> Going from a pure string of SQL or JSON to a concrete type without actually executing any runtime code is pretty crazy. Elixir/Erlang might already be able to do something like this with metaprogramming. It’s certainly possible to generate and run Elixir at compile time, and map types are already a good superset for JSON objects, so a compile time JSON to map could then provide an inferrable type. I think someone more savvy with Elixir would know more. I’d certainly not something that I’ve needed.
erszcz 3y ago
> Going from a pure string of SQL or JSON to a concrete type without actually executing any runtime code is pretty crazy. Going from a JSON string to a type for it is actually one of the easier examples of inference I can imagine. JSON is a data description format in which all the base types are syntactically distinguishable, it has no variables, no arrows (i.e. functions), no generics. In the topic of type inference, you can't have a much easier example. SQL is more complex, indeed, but still doesn't seem too crazy if you have access to table schemas. It's also a matter of whether triggers and stored procedures are taken into account, but I assume they're not. There's a lot of prior art described in literature as well as practical programming implementations with much crazier, yet successfully working type inference.
- Vaguely2178 3y ago
  I just want to make sure we're on the same page here. The JSON example I linked to isn't inferring the types of JSON that's already been parsed and deserialized, that would be trivially easy in any language (including TS). If I have an object that's been parsed from JSON, I can just use the typeof operator in TypeScript to infer the type of that object. The example I linked to is taking a serialized JSON string, and parsing the literal characters in the string (characters like double quotes, commas, whitespace, etc) into a type, purely using type annotations. And the structure of that JSON can be of arbitrary nested depth. All of this is accomplished using template literal types which allow you to make assertions about the contents of a string. In TypeScript you can assert more than just "this value should be a string". You can make detailed assertions about the structure of strings, and that's what allows these parser demos to exist. When you combine these template literal types with recursive types, conditional types, and TypeScript's infer keyword you can do some pretty interesting type level programming. Just to further demonstrate the point, there's an interpreter for the BF programming language, written entirely using TypeScript type annotations [1]. > There's a lot of prior art described in literature as well as practical programming implementations with much crazier, yet successfully working type inference. Has any of this been demonstrated in Elixir? [1] https://github.com/sno2/bf https://github.com/sno2/bf
  - h0l0cube 3y ago