Ask HN: Why are you programming your hobby projects in a niche language?

But I really miss some of Crystal’s features in other languages I work with:

1. Being able to declare union types when ingesting some not-so-normalized data

    alias UserID = String | Int32 | UUID

For example here I have a `storedprop` macro which I can use to define propertied that get saved automatically to a YAML config when they are changed: https://f.lunar.fyi/uRW69B/settings.cr

  class Settings
    include YAML::Serializable

    storedprop host : String = "ddcutil-server.local"
    storedprop port : UInt16 = 3485
  end

The first time, after several years of working with Python, I missed the dynamic data structures like lists and dictionaries. Open arrays work pretty well, but Pascal still requires a lot of overhead to set things up compared to `d = {}`.

The next time I got a bit further with it, but I remember everything being just slightly different enough that I had to dig for examples and documentation to do simple things I used to do easily in Delphi. I think I got some of my old graphics programs working but there was enough friction that I lost interest and moved on.

But its worth giving it another shot since I have a lot of old Pascal code I'd like to play with again, and knowing about these difficulties going in I might do a better job next time.

What I like about Nim is the terse syntax similar to Python, and the more dynamic data structures like sequence, but also the typing similar to Pascal and the compiling to executable thanks to C. I like the V language too for its batteries-included nature, but haven't gotten far enough with it yet to tell if I will stick with it. The docs are a good start, but they only have Discord for a community and that is hard to work with.

I’m already looking into using Keygen for my next non-AppStore app. I’ll definitely reach out if I have any concern. Although from what I saw, your site explains everything well, and the dev tier will be helpful in testing.

I’m not getting 100 RPS constantly. It happens rarely, mostly when releasing updates. When an update is detected, Lunar has to check if the period of free updates hasn’t ended. Then the server is contacted again when the new version is launched.

With 3000 pro users (some received licenses for free because they donated when Lunar was free), 100 RPS can happen for short bursts and the server has to cope well with this even if it happens rarely.

Look in the examples directory for some basic pub/sub code.

The Prolog code that runs in my house is pretty specific to my house so I figured the best way to open source things would be as a framework more than an implementation. You can contact me via issues on the github repo and prod me into adding some more advanced examples - I've learned a lot since my last commit on the repo.

I've started using the Redis functionality recently added to SWI-Prolog, so my code now responds to MQTT messages and uses state queried from Redis to help determine what actions (implemented by sent MQTT messages) to send out. The beauty is that since I don't do anything that blocks significantly in the Prolog code it is now single threaded - even the MQTT listening. It still responds quickly enough and is MUCH easier to deal with than multi-threaded.

An example of what I'm doing is I built a bunch of ESP8266/EESP32 display devices that control neopixels/OLED/LCD displays. When one of those devices boots it sends a MQTT message announcing its location and capabilities (display type, bit depth, dimensions). Prolog receives that message and then stores that info in Redis. So that device info is all dynamic.

So then later Prolog might get a notification that something is in the driveway. All by MQTT it requests an image from the appropriate camera, then sends the image off to Sighthound and deepstack image recognition servers. The Sighthound front end sends a message back to Prolog with a description of any vehicle spotted which Prolog then matches against known vehicles. If it determines for example that a Fedex truck is in the driveway then Prolog sends notifications around the house - it queries all the display devices from Redis and then based on the capabilities of each devices creates a JSON formatted MQTT message to send to each announcing the Fedex truck. It then also sends a MQTT message to some Java code that connects with Google and sends a push message to an Android app I wrote that displays the alert on my phone and watch.

Before I switched to MQTT I was using Prolog with CORBA as the message transport and back then I also had Visual Basic and MS Agent as part of the system. One night I got bored and a little while later had 3 Peedy the Parrot characters singing Row Your Boat in a round across three different computers coordinated by Prolog. It was actually only a page worth of custom Prolog code for that.