Changing a single cell in a table with hundreds of rows and a dozen columns would be a good test.

Rich Harris also created rollup and buble.

He's an inventing and implementing machine.

Also doesn't work on Safari 9.

Why not transpile the Svelte compiler to ES5 so it will run on all browsers? Otherwise devs may get the impression Svelte generated applications will not work on all browsers.

Exactly. My main gripe is that it won't even display the source code. I would be okay with the execution part of the REPL not working, but this just creates the impression that Svelte literally cannot display a block of text without ES6.

I don't want to be too harsh on the Svelte author. It's a minor inconvenience.

The guy did some incredible work - he wrote all of this code in a week. I'll look at the REPL code to see if there's a simple fix. All the levels of indirection, code generation and bundling may take a while for my non-Rich-Harris brain to sort out.