#1868: Exception fails all exception predicates
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Reporter: Orphi | Owner:
Type: bug | Status: new
Priority: normal | Milestone: 6.10 branch
Component: libraries/base | Version: 6.8.1
Severity: normal | Resolution:
Keywords: | Difficulty: Unknown
Testcase: | Architecture: x86
Os: Windows |
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Comment (by Orphi):
Mmm, so there's actually quite a lot of different exception types that you
can't distinguish between currently. That's nice.
I'm not really sure how some of these errors are meant to be different.
For example, what's the difference between an `IllegalOperation` and an
`InvalidArgument`? When would you issue one, when would you issue the
other? Similarly, what conditions does `SystemError` cover that are not
already covered by `ProtocolError`, `HardwareFault` and
`ResourceExhausted`? Is there some documentation somewhere which states
exactly what each type is meant to cover?
The documentation in Sytem.IO.Error seems to suggest that
`IllegalOperation` is intended to be a "catch-all" for any error that
doesn't fall under the other types. Looking at the above, it seems that's
not the case.
I guess probably the best thing to do at this point is just add more
predicates for detecting ''all'' the possible I/O exception types. But the
commands in the quoted code seem to suggest that this would break
compatibility with Haskell 98?
Basically, I'd just like to be able to write an exception handler and know
which exception happened so I can decide what to do. Currently that seems
to be harder than necessary.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/1868#comment:3>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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