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Comment by ReleaseCandidat | Hacker News Reader

> Using an editor that shows type inlays (e.g. VSCode) helps a lot but not fully because a lot of types are inferred as generics.

That is because they are generic most of the time.

This is also fun when using `#trace`in the REPL and all you see is `<poly>` instead of the "real" value

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Right but being overly generic makes them hard to understand. Generics are kind of like "compile time dynamic types" and they have many of the downsides of runtime dynamic types:

* intent of the author not clear

* auto-complete etc. doesn't work as well

* type errors not caught as early (for generics this means you get super confusing type errors)

Obviously some functions are intended to be generic (e.g. operations on containers) but typical OCaml code seems to contain functions that are actually only called with one type - and the author only intended for them to be called with one type - yet they get inferred as generic.

Actually generic types can make reasoning about code much easier. This is the opposite of runtime dynamic types. Generic types tell you what the code doesn't (and cannot) do. Any generic type basically cannot be inspected or unpacked, see the paper "Theorems for free" for examples.

> Right but being overly generic makes them hard to understand.

Oh yes, I'm not arguing against that or your other points. I just wanted to express that the types being inferred as generic is not an error, but by design.

Right, I didn't mean to imply otherwise. Just that that design has big downsides.

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