Ursa to-do

Version 0.3

Map interface to internet.
Next Rosetta Code example: anagrams
Classes: properties, names for List and Map
Ability to use async JavaScript APIs.
Generators and co-routines. A generator in a comprehension gives a lazy list/map.
Make everything objects (arithmetic should be methods of Num).

To optimize symbol references, add var (mutable let), and evaluate as much as we can at compile time. Any expression with no free variables can be fully evaluated.
Study vau, first-class environments (objects), and delimited continuations: https://github.com/catseye/Robin ; also see https://github.com/nukata/little-scheme-in-typescript
Make code readonly. Start with FreeVars. See https://github.com/immutable-js/immutable-js/

Comprehensions: loop [elem, …] and loop {k = v; …}.
100% test coverage.
Tail recursion elimination
Co-routines (copy Python?)
self
Streams, and use as interface to files.
Code formatting: have blank lines between top-level multiline lets, and after the last use in a series of uses.

Inter-working with C. Initial quick-and-dirty version: allow arbitrary C APIs to be declared (especially for POSIX; later add GLib introspection), and allow C bindings to be generated for Ark values that have C types, and any base Ark type.
Type checking; extra for sugar where when an object obj is given as the iterator, obj.iter() is automatically used.
Structs
Enums
Traits (use for built-in operators)
Tuples
Variadic functions?
Slices (implement on lists and strings)
Match statement
String interpolation
Long Unicode escapes
Namespaces
Macros: use for syntactic sugar to get e.g. fn a () { }, and for +=
Module system. Mimic Rust: https://doc.rust-lang.org/rust-by-example/mod/split.html