On Dec 22, 2013 7:28 AM, "Herbert Valerio Riedel"
On 2013-12-22 at 11:32:20 +0100, Thomas Schilling wrote:
Looks like GHC HQ maintains this package. I don't think it'll make it into the version released with 7.8, though.
fwiw, I've been wanting to review that submission but didn't get to it yet;
I do have another question, though. How should Haskell code using the `unix` library check for whether `fsync` are implemented or not?
there's a HsUnixConfig.h include file generated (and installed) you can include from your Haskell code, and use CPP
If I call `fsync` I wouldn't want to get a runtime `error` call if the platform doesn't support it.
To be fair, `unix` does not seem consistent with respect to handling potentially missing lib/syscalls; I've seen the following three cases:
a) fallback to implement semantics via different calls (e.g. `System.Posix.Env.unsetEnv`), or
b) the implementation returns bottom via an `error`-value (e.g. `System.Posix.Temp.mkstemps`), or
c) the symbol is conditionally exported (e.g. `System.Posix.Directory.tellDirStream`)
Either I should be able to check at compile time, or I should get a defined exception call which then must be handled by the library. In either case it should be documented with the function.
It might be worth adding more information to the Haddock-comments mentioning the respective `HAVE_*` CPP symbol and whether a fallback-implementation is used.
Moreover, the use of `error` to signal non-existing implementations could be reconsidered (e.g. maybe switch to a properly thrown "call-not-implemented" exception)
This would definitely be better than calling error. Personally I would prefer conditional exports, as it would turn up errors sooner. John L.