Foreign.C.Error (original) (raw)
Haskell representations of errno values
newtype Errno Source
Haskell representation for errno values. The implementation is deliberately exposed, to allow users to add their own definitions of [Errno](Foreign-C-Error.html#t:Errno) values.
Common errno symbols
Different operating systems and/or C libraries often support different values of errno. This module defines the common values, but due to the open definition of [Errno](Foreign-C-Error.html#t:Errno) users may add definitions which are not predefined.
[Errno](Foreign-C-Error.html#t:Errno) functions
Guards for IO operations that may fail
throwErrnoIfSource
Arguments
| :: (a -> Bool) | predicate to apply to the result value of the IO operation |
|---|---|
| -> String | textual description of the location |
| -> IO a | the IO operation to be executed |
| -> IO a |
Throw an [IOError](System-IO-Error.html#t:IOError) corresponding to the current value of [getErrno](Foreign-C-Error.html#v:getErrno) if the result value of the [IO](System-IO.html#t:IO) action meets the given predicate.
throwErrnoIfRetryMayBlockSource
Arguments
| :: (a -> Bool) | predicate to apply to the result value of the IO operation |
|---|---|
| -> String | textual description of the location |
| -> IO a | the IO operation to be executed |
| -> IO b | action to execute before retrying if an immediate retry would block |
| -> IO a |
as [throwErrnoIfRetry](Foreign-C-Error.html#v:throwErrnoIfRetry), but additionally if the operation yields the error code [eAGAIN](Foreign-C-Error.html#v:eAGAIN) or [eWOULDBLOCK](Foreign-C-Error.html#v:eWOULDBLOCK), an alternative action is executed before retrying.