[Haskell-cafe] Library for overloaded indexing (a la (!))

[Roman Cheplyaka]

On 14/08/15 09:21, William Yager wrote:
> If I mis-index a vector, I don't want it to fail silently with mempty; I
> want it to fail loudly. What you've described (default value on
> out-of-bounds access) is not correct for most use cases. Sometimes
> exceptions are the right behavior.

Precisely.

«An element is not found, so I'll just return 0[*] or "".» Even
JavaScript knows better than that.

Granted, there *is* a way to use this API properly (using Maybe-like
monoids). But it's also easy to make the wrong code type-check without
realizing it.

[*] that's essentially what Nikita proposed earlier in the thread

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