Necessary:

• Add support for min, max, repeat as new expressions.
• Add support for reading input as new expressions.
• i10n of error messages
• Better output format (do not use Debug)
• Error out with empty arrays
• Web editor
• Web debugger

Useful:

• Add integration with terry
• intrinsic "error", "debugger break" to populate debugger timeline
• Getting started guide
• Add support for builtin functions and methods
• Make special expressions built-ins instead
• Add support for generics

Maybe:

• block editor