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Incidently, there is a wave of popular python projects in dev python spheres that use types to define validation and serialization: fastapi, typer, etc. Grante

Incidently, there is a wave of popular python projects in dev python spheres that use types to define validation and serialization: fastapi, typer, etc. Granted, the python typing system is very limited, and to get complete validation, you'll need more than types as python type hints can't express complex rules. Also, as the articles mentions, the validation will occur at runtime, it can't in any way make sure the program is valid from mypy checks alone. Still, it's really nice to define your input data types and contraints in one go.

pdhborges 4y ago
The Python typing system is limited compared to what exactly? It already has union types, generics, bounded generics, union types, literal types and structural subtyping.
- pdimitar 4y ago
  Compare it to Haskell, OCaml and Rust and it looks like a toddler tripping all over itself compared to an adult athlete running at a steady 20km/h. There are libraries in these languages where you can get a compile error if you make a mistake in an SQL statement. Also, Python technically has no typing system to speak of so your comment is kind of strange. Not to mention pattern matching, destructuring and other goodies that improve productivity.
  - pdhborges 4y ago
    > Compare it to Haskell, OCaml and Rust and it looks like a toddler tripping all over itself compared to an adult athlete running at a steady 20km/h. Well that is a pretty tall order. Those languages probably have the most extensive type systems among the languages with significant use. But even so Python's type system has features that some of them don't have: for example Rust doesn't have structural subtyping. > Also, Python technically has no typing system to speak of so your comment is kind of strange. Python PEPs define the typing annotations and the typing rules for each annotation. That for me counts as a type system, despite the fact that there is not built in typechecker and you can run programs that you didn't type check. > Not to mention pattern matching, destructuring and other goodies that improve productivity. Python has pattern matching now: https://peps.python.org/pep-0636/ https://peps.python.org/pep-0636/

pdhborges 4y ago

The Python typing system is limited compared to what exactly? It already has union types, generics, bounded generics, union types, literal types and structural subtyping.

pdimitar 4y ago
Compare it to Haskell, OCaml and Rust and it looks like a toddler tripping all over itself compared to an adult athlete running at a steady 20km/h. There are libraries in these languages where you can get a compile error if you make a mistake in an SQL statement. Also, Python technically has no typing system to speak of so your comment is kind of strange. Not to mention pattern matching, destructuring and other goodies that improve productivity.
- pdhborges 4y ago
  > Compare it to Haskell, OCaml and Rust and it looks like a toddler tripping all over itself compared to an adult athlete running at a steady 20km/h. Well that is a pretty tall order. Those languages probably have the most extensive type systems among the languages with significant use. But even so Python's type system has features that some of them don't have: for example Rust doesn't have structural subtyping. > Also, Python technically has no typing system to speak of so your comment is kind of strange. Python PEPs define the typing annotations and the typing rules for each annotation. That for me counts as a type system, despite the fact that there is not built in typechecker and you can run programs that you didn't type check. > Not to mention pattern matching, destructuring and other goodies that improve productivity. Python has pattern matching now: https://peps.python.org/pep-0636/ https://peps.python.org/pep-0636/