New blog post: Context and capabilities in Rust
tmandry.gitlab.io/blog/posts/202
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And why does everyone seem to use them in Scala if they aren't used in Haskell?
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'implicit parameters' can refer to a bunch of features for filling in parameters. In Scala the insertion is more like type class instance search, in Agda/Coq/Idris it's more like filling in generic type parameters, in Haskell it's more like looking up a name bound in scope.
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I had bumped into some of these differences, but didn't have the expertise in any of these languages to be confident. Thanks for this!
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No worries! I think it's pretty interesting to see how the differences affect how they are used, along with various community norms. But yeah, I sometimes feel it's a bit frustrating that they all have the same name.
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Oh, one other thing to note: Agda's instance arguments and Coq's class binders are a bit closer to Scala's implicit arguments, and OCaml's modular implicits, IIUC.
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Oh, even within that there is subtlety. Like Scala's implicit search uses a complicated fallback strategy on ambiguity, which can make it challenging to understand what instance is being selected, whereas OCaml's proposed implicits instead plans to provide an error.
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You'll get lots of people grumpy about the mistakes Scala's implicits made, but there's a decent amount of room to make different choices here! Just be very careful when referencing them, as people's feelings are… strong when it comes to them.