laszlopandy / elm-console Goto Github PK

First of all, thanks for picking this up for Elm 0.16!

I was trying to use elm-console in a context where I have a Task that produces a String, and I want to write this string to the console. Here's some code to illustrate:

task : Task () String
task =
    Task.succeed "String"

io : Task () (IO ())
io =
    Task.map Console.putStrLn task

port runner : Task () (Signal (Task x ()))
port runner =
    Task.map Console.run io

Now, in this case the Task is obviously trivial, but imagine code where there really was an substantial Task involved that ultimately could be mapped to a String.

The code above will compile, but it doesn't really make any sense (and doesn't work), because a Task which results in a signal of tasks isn't really sensible within Elm, for a variety of reasons. So, it's a dead end.

So, I was trying to conceive of what is missing here. One way of thinking about it would be that we need a function of this form:

fromTask : Task x a -> IO (x, a)

Now, one complication for implementation would be arranging for the task to be executed when the IO is executed, but that doesn't seem impossible.

If one had this "bridge" between Task-world and IO-world, I think it would cover a lot of cases.

Some others one could imagine are:

onSuccess : Task x (IO a) -> IO a

onError : Task (IO x) a -> IO x

So, I'm wondering whether I'm thinking about this the right way -- is there a better way to imagine how this might work?

In passing, I think there are similar puzzles re: Signals and IO ... for instance, what if you had a Signal String and you wanted to write each String to the console as it arrived? I'm not sure how you'd do that either, but I haven't thought much about it.

I wish I could send you a PR for upgrading from 0.16, but now that Signal is gone I'm not sure how to do it....

Hello,

So, I'm using elm-console to run elm-test tests. But I have the case where I'm trying to test signals and effects.

Long story short, I manage to end up with a Signal Test, and I need to map those tests to consoleRunner then Console.run to run the tests each time a new test comes from the signal.

But Console.run takes an IO and returns a Signal of Tasks, so I would end up with Signal (Signal (Task.Task x ())), and Signal of Signals aren't allowed in elm.

My workaround to solve this was creating this library: signal-concat-map that allows me to concatMap signals, by using native modules.

You can check out the final code of the TestRunner here.

I wouldn't need this if there was a way to run signals of IO, like this:

Console.runSignal : Signal IO -> Signal (Task x ())

Is this possible in elm-console?

Thanks!

Full details are here deadfoxygrandpa/elm-test#32 (comment)

Essentially what is going on is that I am seeing

require is not defined


Open the developer console for more details.

Appears to be happening because when compiling my test code with webpack via the elm-webpack-loader. module.exports = Elm; is appended to the resulting file making the current guards around the require call insufficient.

Fix seems to be to just add a check to see if require is defined. Will send out a pull request.

Hi, can you bump up the version to work with Elm 0.18.0?

It would be nice to read from a file. readFile : String -> IO String. An invalid path would be the same as pure ""; alternatively it may return an IO (Maybe String) or similarly with a Result.

If you like the idea but don't have time to implement it, I could sent a PR sometime next week.

Hello!
Love your work!
Im here asking if there will be a port over to elm 0.17?

Elm 0.16 is too outdated. I'm upgrading this package for Elm 0.18 at openirc/elm-console