Signals in Elm
Here’s the translation of the Go code to Elm, along with explanations in Markdown format suitable for Hugo:
Our first example demonstrates how to handle signals in Elm. While Elm is primarily used for web applications and doesn’t directly interact with Unix signals, we can simulate a similar behavior using Elm’s built-in Platform.Sub
for handling external inputs.
In this Elm program, we simulate signal handling using a subscription that triggers every 5 seconds (simulating a SIGINT). Here’s a breakdown of the code:
We define a
Model
that keeps track of the received signal and whether the program is done.The
update
function handles two types of messages:ReceiveSignal
(simulating receiving a signal) andFinish
(simulating program termination).We use
subscriptions
to set up a recurring event that simulates receiving a signal every 5 seconds.The
view
function renders the current state, showing whether we’re awaiting a signal, have received one, or are exiting.In the
main
function, we set up the Elm application with our definedinit
,update
,subscriptions
, andview
functions.
To run this Elm program:
- Save the code in a file named
Signals.elm
. - Compile it using the Elm compiler:
elm make Signals.elm --output=signals.js
. - Create an HTML file that includes the compiled JavaScript and run it in a web browser.
This example demonstrates how to handle external inputs in Elm, which is conceptually similar to handling signals in other languages, albeit in a web context rather than a system-level one.