aot.org

The Problems With Clojure AOT Compilation.

1. The name is not clear.
   • The name is short hand for something, but it can easily be bandied about and ends up being used without understanding what it signifies.
   • The compilation model
     • reader
     • compiler
       • not interpreted
     • the jvm executes bytecode
     • AOT compilation saves the output of the compiler so it can be executed later instead of immediately.
   • AOT performance advantages
     • start up time
2. The ABI is not stable.
   • ABI is Application Binary Interface
   • Can mean a lot of things, and I am sort of abusing it using it here.
   • In this case I mean how Clojure functions are linked to each other, how they are invoked and how they are looked up.
     • similar to discussions of calling conventions if you are familiar with that.
   • Changes to how functions are linked is kind of hot topic right now
     • lazy loading
     • performance
       • differences between Clojure class size and Java
   • Unstable abi means code compiled with Clojure version X is incompatible with code compiled with Clojure version Y
     • Most clojure code will work with many different versions of Clojure.
     • Once you AOT compile a library though, consumers can only reliable use the library with the same version of Clojure it was initially compiled with.
3. Clojure’s compiler is transitive.
   • Some interest solutions to this
   • Lein hacks and work arounds
4. Pithy summary
5. What are alternatives to AOT compilation?
6. What does responsible use of AOT look like?

• Maintaince burden of AOT