The article mentions that global type inference is painful, and Rust made the right call by requiring annotations, but actually I think the OCaml model is closer to the optimum: you can still annotate functions and perhaps you should (in fact the interface files are in my view great, but not everyone enjoys them), but the key benefit is that you can also use holes in such definitions, e.g.
_ option list
is usually quite descriptive of what data you have, but still doesn't go into some detail you don't want to (sadly "int _ list" isn't supported by the type system). The types in Rust can sometimes get quite long, in particular if you want to avoid boxing and you're dealing with futures.
I imagine there's as sweet spot between type inference, an LSP "add type annotations" action and a "function missing annotations" warning option. Smooth out the exploratory stage, flip to "strict" with one button and a way to enforce "strict" mode.
I actually find that annotated parameters and return types help me during the exploratory stage too otherwise I invariably end up making a typeerror somewhere and the errors aren’t helpful (the error shows up in the wrong spot, or the function mysteriously changes type)
I second the point that Rust types can get quite long. I usually use aliases where I can but that isn’t always possible. I think that sometimes people use boxing just to avoid these long types even if the code in theory doesn’t require an allocation
