unison/docs/runtime-calling-conventions.markdown

Lambda

• called with arguments in declared order.
• whenever a lambda is called, it takes itself as rec
• it evaluates the body passing the bound lambda parameters on the stack

Computation

• bound variables passed on stack with innermost scope closest to index 0
• "rec" is passed as well (?)
• evaluations in nontail positions need to catch handle TC because their "frame" has more work and shouldn't be thrown away; evaluations in tail positions can throw their tailcalls upward and discard their frame
• let1/letrec evaluate the bindings with the existing stack (bound variables in their scope); body is called with bindings prepended to stack
• compilevar returns rec if its name matches currentRec, otherwise looks up a value on the bindings stack
• compilelambda returns a computation that will produce a lambda when evaluated
• apply
  • if fn name matches currentRec, then staticRecCall
    • staticRecTailCall
      • throw selfTailCall with evaluated args (seems like this would not do anything) (?)
    • staticRecNonTailCall
      • call (rec: Lambda) with evaluated args
      • a SelfCall exception should never escape the wrapper lambda
  • else compile fn
    • if compiled fn is Return(Lambda)
      • staticTailCall
        • throw tailcall with fn
      • staticNonTailCall
        • call fn with rec = fn
    • else compiled fn is not yet a lambda, and needs to be evaluated again (at least once)
      • dynamicTailCall
        • eval mkFn and assume it produces a lambda (it should)
        • throw tailcall with lambda and eval'd args
      • dynamicNontailCall
        • eval mkFn and assume it produces a lambda (it should!)
        • call lambda with evaluated args

Tail calls

tailcall throws an exception with the target function & args selfTailCall throws a tailcall with null(implied?) function

when a tailcall exception is caught, we enter a while loop which calls the target function and continues to catch tail calls until the target function is null.

note that the selftailcall begins with null. (?) don't understand

annotated bounds