Dave, how do you think about JavaScript Promises? Where you code for the happy path (the chain of Promise.resolve().then().then().then()), any of which can throw, and have a .catch() handler that catches whatever the thrown value was and does something about it. The Elm Result type is very similar to this.
Promise.resolve(myValue) ~= Ok myValue Promise.reject(myErrorData) ~= Err myErrorData promise.then(fn) ~= myResult.andThen(fn) or myResult.map(fn) promise.catch(fn) ~= case myResult of Err x -> fn x Again, a specific example would help. Elm programs are not written the way C, C#, Java programs are written. Clojure is closer but because of Java interop reasons hasn't adopted much of the Maybe / Result / ... goodness and instead has nils like Java has. In Elm the erorrs are explicit (like you say, part of the return type). Read: http://blog.jenkster.com/2016/06/how-elm-slays-a-ui-antipattern.html for how Elm solves the Server Down error you mentioned. Malformed JSON is also reported not with exceptions but with Result. Either you get your value in Ok, or helpful error message in Err. You have to handle both cases, it doesn't propagate up, it doesn't throw a runtime exception, the user sees what you decided to show him in that scenario. Essentially the Elm compiler tells you "This could blow up - you told me what to do if the JSON is OK, but what if it is not?" On Friday, October 7, 2016 at 10:05:50 PM UTC+2, Dave Ford wrote: > > > > On Fri, Oct 7, 2016 at 11:33 AM, Kasey Speakman <[email protected] > <javascript:>> wrote: >> >> Then at the edge of the application, I can deal with the errors >> > Yes. This is what I am trying to figure out. How to deal with that class > of errors at the "edge". > > Thanks. > > -- You received this message because you are subscribed to the Google Groups "Elm Discuss" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
