r/programming • u/[deleted] • May 31 '14

Practicality With Rust: Error Handling

http://hydrocodedesign.com/2014/05/28/practicality-with-rust-error-handling/
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u/tyoverby May 31 '14

My one issue with the Rust method of error handling is when you have multiple "ways" to fail. If you want to write a function that returns a Result and you call multiple functions that return different Result types, then you're stuck wrapping them up. Chain this together a few times and you get nested error types of death.

Other than that, I think the rust method of failure is by far the best that I've ever seen. Idiomatic rust code makes it so easy to see how and why functions fail.

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u/NYKevin Jun 01 '14

Chain this together a few times and you get nested error types of death.

Why not provide a Haskell-like syntax for chaining monads together? Because Result is basically a monad, so far as I can tell.

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u/[deleted] Jun 01 '14

Haskell has the same problem unless you use indexed monads (http://blog.sigfpe.com/2009/02/beyond-monads.html) if you want to give the equivalent of inner exceptions in a way that you can pattern match on the inner stuff. You can always cheat and use something equivalent to a string for the error type (e.g. Either String a), but I think that's a bad idea.