result compatibility package.Stdlib.Result module available in OCaml 4.08.R.failwith_error_msg.R.[k]ignore_error use a thunk for the ~use argument. This is an incompatible change. Simply wrap occurences of ~use:e with ~use:(fun _ -> e).R.pp remove the pp_ prefix from the labels and do not print the constructors names, use to the newly introduced R.dump for this. This follows the conventions of Fmt.Result compatibility library. Opening Rresult still gives you both unprefixed variant constructors and infix operators.R.{int,nativeint,int32,int64,float,bool}_of_string functions. They do not belong here.R.map, swap argument order. Thanks to Gabriel Radanne for suggesting.R.bind which had a more restrictive type than >>=. Thanks to Hezekiah M. Carty for the patch.Rresult_infix module no longer exists. Open directly Rresult for using the library.First release.