Test students' ability to design a simple statically-typed programming language and implement its toolchain: specify syntax and type system, build a lexer and parser that produce an AST, implement an AST-based static type checker (including function types and recursion checks), and create an interpreter or bytecode compiler/executor supporting variables, conditionals, recursive functions, and basic types (ints, booleans, strings). Evaluate correctness, type error reporting, and sample programs demonstrating recursion and control flow.