A direct (+ 1.5M 2.5M) emits a raw Chez + that rejects the bigdec record. Rather
than guard every arithmetic call site (measured 2-4x on unhinted fixnum loops),
let the analyzer dispatch where it can prove the type.
jolt.passes.numeric seeds a :bigdec kind from the M-literal and flows it through
let/loop/if like the existing :double/:long kinds; an arithmetic/comparison invoke
whose operands are all bigdec (integer literals allowed) gets :num-kind :bigdec.
The back end (bd-ops + emit-numeric) lowers those to the bigdec.ss engine
(jbd-add/-sub/-mul/-div, jbd-lt?/…, jbd-zero?/-pos?/-neg?, jbd-quot/-rem).
Zero cost on non-bigdec code: with no bigdec literals present the kind never
arises, so emission is byte-identical — the re-mint leaves prelude.ss unchanged,
only image.ss (the compiler) moves. Gaps (filed): a bigdec mixed with a flonum in
call position, and a bigdec the analyzer types :any, still hit the raw op and
throw; use value position or a literal-typed let.
Re-mint (numeric/backend are seed sources). 16 JVM-certified corpus rows.
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