math
Layered mathematics stack — libm, linalg, calculus, tensors, autodiff, NN, SSM, agents, pure math.
hash — digests, grouped by guarantee
checksum / fast / crypto / legacy. The four are not interchangeable, and the mount line says which one you rely on.
mac — HMAC + Poly1305
Keyed message-authentication codes — HMAC-SHA-2 family and Poly1305 one-time authenticator.
subtle — constant-time ops, zeroization
Operations defined by what the machine must NOT do — reveal timing, or elide a wipe.
random — secure vs deterministic
Two kinds of randomness under one name, so the choice is made once, deliberately, at the mount line.
id — unique identifiers
UUID, ULID, NanoID and Snowflake. Not primitives of the language — they read a clock and draw entropy.
simd
Portable SIMD — Vec<T,N>, Mask<N>, arithmetic, reduction, shuffle, gather/scatter, GPU.