No new screencasts to show this week. I’m in the middle of doing some much-needed refactoring. What happened? As of the last update, I had a decent expression editor. The missing final piece was adding a declaration layer to the editor, allowing a Unison panel to be edited much like a module in a regular programming language.
I hate type errors!
Here’s a video of the latest progress. In this video, I create the term
view reactive (1 + 1), which displays in the editor as
2. This might not seem like much, but the ability to define reactive views like this is the first step in allowing Unison panels to be used much like a spreadsheet, where the user fills in values and other parts of the panel are updated in response. There’s also a few other things shown which I’ll talk through below:
Here’s a video of the latest progress. Watch me write the expression
1 + 1, then evaluate it!! Further explanation below.
When programming in a language with a nice type system, you often have the option of defining ‘smart’ data types which bake some invariant in as an index of the data type. But sometimes, it can be better to keep your data types dumb, and layer on invariants after the fact. The lesson generalizes, but I’ll show an example—well-formed lambda calculus terms: