Kitty Lang

Kitty Lang is a work_in_progress programming language, basically "what if Rust was a friendly scripting language".

Kitty Lang is intended to be used as the foundation for Village Kit, a future-thinking code-as-CAD system for open source makers.

Principles

• Accessible to beginners, like Logo
• Powerful for experts, like Haskell
• Structs and traits, like Rust
• Embeddable, so can be used in web or native apps
• Language-aware, so compiler can be used as linter, formatter, language server, etc
  • Even if some syntax is wrong, the compiler is able to parse the remaining correct syntax and still give useful feedback
• Debug-friendly, so you know exactly how and why something went wrong
• Evaluation-aware, so you even know where values come from
  • Every value has a reference to the code span which created it
  • This is important for code-as-CAD editors where you can interact with an object in 3d space and it performs a macro on the code
• Secure, so you are safe with untrusted input
• Inspired by future-thinking languages: Julia, Flix, Gleam

Progress

At the moment

• Lexer (String -> Tokens)
• Parser (Tokens -> Concrete Syntax Tree)
• Analysis (Concrete Syntax Tree -> High-level Intermediate Representation)
• Evaluator (High-level Intermediate Representation -> Value)
• ???

Language

(Incomplete)

• Rust-like type system
  • Primitives
    • (): Unit type
    • Number
    • String
  • Compound types:
    • (T, U...): Tuple
    • List
  • Enum types:
    • Boolean
    • Option
    • Result
• Functions can be called with either positional args or keyword args
  • Type generics are the same
• Functions can describe multi-arity multi-type overloads
• Only top-level declarations and expressions
  • In let, a newline is an implicit in.
• Use only where clause to describe type trait bounds, not in generic params
• Use . instead of :: for type paths
• Use [] for generics, use () for tuples, use List() for lists, use list.get and list.set for get and set.
  • Although Flix seems to be able to use [] for generics AND lists.
• Use labelled arguments like Gleam: https://tour.gleam.run/everything/#functions-labelled-arguments
• Match like Gleam: https://tour.gleam.run/everything/#data-types-record-pattern-matching
• True and False are part of a Boolean enum
  • but they are aliased so you can use as True and False.