See also ‣

Techniques

• Reflection: Several approaches (e.g. towers, Java-style, MOPs) which vary in support for: introspection (read) vs. intercession (write), structural (classes, methods, fields) vs. behavioural (assignment, creation, invocation)
• Reflective tower: Run-time structure and behaviour changes (”full reflection”) of language system, very powerful but difficult to optimise
• Syntactic macros: Compile-time host language procedure or pattern that transforms input program
• Multi-stage programming: Code generation and execution, with potentially several stages chained together, typically run-time (but not always), some amount of static type safety

Time

• Compile-time: macros (Lisp, Scala, etc.), multi-stage programming (Template Haskell, Metalua, Converge, Mython, Delta)
• Run-time: reflection (Black etc.), multi-stage programming (MetaML, MetaOCaml, Metaphor, Mint, LMS, Terra)

Space

• [ ] Read time and space paper

Implementations

• Scala LMS: Run-time code generation technique, applied to many research problems
• Scala 3 / Dotty: Both compile-time macros and run-time code generation
• Terra: Run-time code generation of static Terra code via dynamic Lua
• [ ] Add more to highlight others of interest

Use cases

• Languages become malleable: users can provide language-level features themselves
• Modifying / overloading language semantics
• Code reuse that goes beyond typical language abstractions (functions etc.)