A Logos decimal literal: 10.99M, 3M, -2.5M -- Clojure-style arbitrary-precision, exact-scale decimal arithmetic. Unlike float (IEEE 754 binary floating point, can't represent 0.1 exactly) and unlike Logos.Ratio (always reduces to lowest terms, so 10.10 loses its original "two decimal places" the moment it becomes a ratio), a decimal preserves the scale it was written with: 10.10M prints back as "10.10M", not "10.1M".

A thin module, not a new struct -- Logos decimal values are the decimal hex package's own %Decimal{} struct directly, reused as-is rather than wrapped a second time, the same way Logos.Vector reuses Erlang's :array instead of reimplementing one. new/1/to_string/1 here are the only genuinely Logos-specific pieces: parsing straight from the reader's own literal text, and printing with the trailing M Clojure's own printed form keeps (the bare decimal package's own to_string/1 does not add one, since M is a Logos/Clojure reader convention, not something decimal itself needs to know about).

Deliberately not aliased to bare Decimal anywhere in this codebase (see e.g. Logos.Printer) -- decimal the hex package already exports a module literally named Decimal, so keeping every Logos-side reference fully qualified as Logos.Decimal avoids any ambiguity about which one a given alias/pattern match means.