Re: [MirageOS-devel] Using Result instead of Option in libraries

[David Scott <scott.dj@xxxxxxxxx>]

On Fri, Oct 14, 2016 at 2:51 PM, Anil Madhavapeddy <anil@xxxxxxxxxx> wrote:

We have quite a few base libraries that use the pattern of

val foo_exn : ... -> 'a
@raises

val foo: ... -> 'a option
Gobbles the exception and returns Some/None

Should we take the Mirage3 opportunity to port libraries like Ipaddr to using the Result type instead, so it would be

val foo : ... -> ('a, [`Msg of string]) result

instead, using the Result type?  That would let libraries use combinators such as Rresult, and not gobble errors from parsing silently.  It would be an incompatible API bump so we would need to bump all consumers of, e.g. Ipaddr  http://docs.mirage.io/ipaddr/Ipaddr_unix.V4.html simultaneously.

Personally I like the sound of this-- it's nice to use combinators to parse a more complicated structure and be able to emit something more useful than "None" as an error. Should we write a "recommended conventions" doc or wiki page to include things like `foo_exn` and `foo` examples above?

Cheers,

Dave

 

Anil

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--

Dave Scott

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