Absolutely there is a reason. Exceptions are very expensive, especially in low-level functions. In the situation you're talking about, it's a simple logic error in the calling code. That situation will never happen in bug-free code.
This is very different from the situation with something like a file operation where "disk full" is a genuine exceptional situation.

On Thu, 1 Nov 2018 at 09:02, Richard Palme via phobos <phobos@puremagic.com> wrote:
Is there a reason why so few functions in phobos throw
exceptions? For example there is std.bitmanip.BitArray.flip that
gets an index as argument and flips the bit that the index
references, and this function does not throw an exception when
given an invalid argument.

I'd be willing to fix this, but first I wanted to ask if there
might be a reason for this. I think that throwing an exception
should be preferable to a segmentation fault (which happens in
the case of BitArray.flip).
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