Beginner questions about signals

[Andy Nicholson]

Hi everyone,

I'm from a Ruby background, so it's fun learning to deal with static types instead of Ruby's fluidity :)

I'm building a hangman game as my first foray into Elm, and I can render the state of a game into a browser window.

here's my code: http://github.com/anicholson/elm-hangman

I want to be able to register keystrokes as guesses, so they can update the model Signal. I know that Keyboard.keyPresses is the signal I want to track, I just don't know how to "bind" that value change into my model.

Can someone help, please?

Thanks,

Andy Nicholson

@andrewdotnich

[Max Goldstein]

You're really close!

At the top of the file add

import Keyboard

import Char

At some point, define

keypresses = Signal.map (Char.fromCode >> Guess) Keyboard.presses

The >> symbol is function composition: it takes each press, converts it from a charCode to a Char, and then wraps it in the Guess tag. Then in model replace actions.signal with (Signal.merge keypresses actions.signal). That should do it.

(It's possible to send the keypresses to the mailbox instead of merging, but that requires a port, which should be avoided if it's ease to do so like here.)

This is a great first foray and I hope you stick around.

[Andy Nicholson]

Thanks Max!

I'm so nearly close to calling this example "finished" - but with one hiccup.

I have a module with a list of words, which I want to randomly pick a word from. I created a port, and tried to inject a timestamp into my App as a random seed. But the code as it stands causes a stack overflow.

What have I done wrong?

http://github.com/anicholson/elm-hangman

[Corey Trampe]

I left a note on the last commit, in the index.html.

Initialize a port:

    var app = Elm.embed( Elm.Main, stageDiv, {myPort: 42} );

Send a value into a port:

    app.ports.myPort.send(138);

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