WasmPascal v1.1.4: The WEB Unit Expands

20-09-2026



The uses WEB unit got some attention and better examples. String and number handling bugs got fixed. There's also a bunch of small bug fixes in error and warning messages and I have been busy writing a lot more tests for features to try and prevent drift as this project is getting really complicated really fast.

The new compiler and examples are live at wasmpascal — the version badge in the toolbar should read v1.1.4.

In this post

  1. The WEB unit Expands
  2. Strings bugs addressed
  3. Numbers bugs fixed
  4. So many fixes

1. The WEB unit Expands

Until now, working directly with the DOM was a bit cumbersome. I realised that there were some opportunities to improve things, so the WEB unit got some much-needed updates. 

program paint;
uses WEB;
begin
  { ... no hand-rolled bridge anymore ... }
end.

I updated pascalsweep, paint, musicbox and colors to use the uses WEB unit. Paint and MusicBox were still hand-rolling bridges, which is just a lot of work.

There is also a new debug message: putting uses WEB next to another ABI's entry point is now a compile error. Before, it produced a blank page and no explanation at all which was really irritating.

2. Strings bugs addressed

Strings had a 255-byte concatenation cap because I had trouble getting memory allocation working properly. I finally figured this out and I believe you can now have proper strings in the code with concatenation. I've updated some of the examples along the way, but that's an ongoing effort.

Val got two updates: It now zeroes its target when the string fails to parse (previously the old value survived, which made debugging a pain), and Val into a Single parses through a scratch value so the conversion is precise. Previously this was pretty lose...

3. Numbers bugs fixed

Three fixes landed for Numbers:

First, writeln(x:8:2), compiled with exit code 0 and then failed to start, because the compiler emitted a console_float import that didn't exist yet. readln(name) on a string had the same issue with (console_read_str). This has been addressed.

Second, passing a Single to Sin, Cos and such emitted an invalid module: the argument went over as f32 while the import expects f64. I've fixed this, hopefully, in all places.

Lastly, Str on reals was rather crappy and I have rewritten it. It should be more reliable and accurate now.

Try it out

Everything is live at https://wasmpascal.com/. Try writeln(pi:0:4) in the console example, check out the uses WEB unit, or feed Val a string that is not a number and watch the target come back zeroed. Then pick an example — Flight Leader, Pascaloids, Xonix, Minesweeper, Pong — hit Run, and have some fun with Pascal in your browser.

The examples and tutorials live in the wasmpascal_examples repository, and earlier writing about the project is on the blog:



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