rontolisp:with-arena

(rontolisp:with-arena () body...)

Runs the body and returns its value, naming a memory-reclamation boundary for the non-GC WASM backend (--no-gc). On that backend nothing is freed within one export call — the bump allocator only pops at the export boundary — so a loop that allocates each iteration (string building, fresh vec: vectors) grows the linear memory. with-arena closes that gap: it snapshots the bump heap pointer, runs the body, and pops everything the body allocated, keeping only the body's own value (a string or packed float array result is copied down to the snapshot point). On the interpreter, the JVM backend and the default (wasm-GC) output a real garbage collector already reclaims, so it is observationally a plain progn and the same source runs on every backend.

Arguments

• An option list, which must currently be empty (()); it is reserved for future options.
• The body forms, evaluated in order like a progn. The value of the last form is the value of the whole expression (nil for an empty body).

The escape contract (--no-gc)

Nothing allocated inside the body may be reachable after it, except the body's own value. Storing an inner allocation somewhere that outlives the arena (for example writing it into an array created outside) leaves a dangling pointer once the arena pops — the same rule as the host-side __ronto_alloc_reset (Reclaiming memory).

A typical use — keeping a hot loop flat on --no-gc:

Limitations

• The option list must be empty; a non-empty option list is an error.
• On --no-gc, a return that exits across the arena boundary skips the pop (the allocations inside are simply not reclaimed; nothing is corrupted).
• Macros have no function value: #'rontolisp:with-arena is an error.