ROOT CAUSE of the weaker design: "C has no closures" was taken as a fact about
what is possible. It is a fact about one grammar. Every C++ lambda, every Go
closure, every Rust closure compiles to a struct of captured values plus a
function pointer -- which is what is emitted here. Codegen emits C; it is not
written in C's syntax, and the distinction is the whole difference between a
construct that can only decide whether to repeat and one that controls
invocation.
It would also have crippled the JS backend, which has closures natively, for a
limit that applies only to the C one.
PREDICTIONS AND RESULTS
1 env struct + thunk taking void* TRUE
2 fails to compile: struct redefinition FALSE -- C allows the
inner declaration to shadow. Prediction wrong; C is more permissive than
assumed. A different real defect surfaced instead: a wrap with no exit
construct emitted `(EL_STR("f"), EL_STR(""), __r);` -- a call to an empty
target -- because has_exit was reused as "needs a wrapper" and the exit line
was emitted unconditionally. Fixed.
3 compiles when the target is declared in El FALSE -- and this is
the root cause worth keeping: El has ONE type, el_val_t = int64_t. El's type
system cannot describe a callable, so `extern fn` and the real signature
cannot be made to agree in El's own vocabulary. The fix is not a cast:
codegen DEFINES the wrap calling convention, so codegen emits the extern
declaration. The convention is not El-expressible; it is emitted.
4 target controls invocation, 0..N times TRUE
5 existing @manager output byte-identical TRUE
6 compiler fixpoint holds TRUE
7 emitting the convention makes it compile TRUE
MEASURED
base(5) wrapped by a target that invokes the body twice and sums -> 10
never_runs(5) wrapped by a target that never invokes it -> 999
Neither is expressible by "decide whether to repeat". This supersedes the
repeats_body experiment on experiment/repeats-body, which was built around the
mistaken limit.
bigmerge
2bed8483f7