T.choice

A literal: a random schema from a set of schemas, then fabricated.

T.choice.uniform([T.always(null), T.number.whereby({ min: 0, max: 100 })]);
 
T.choice.weighted([
  [3, T.string.whereby({ length: { max: 10 } })],
  [1, T.number],
]);

Same idea as T.enum, but between arbitrary schemas instead of literal values. T.enum draws one of several fixed values directly; T.choice draws one of several schemas and then fabricates from whichever one wins — so each option can itself be dynamic, nested, or composed from other primitives.

There's no bare T.choice(...) — pick .uniform or .weighted. Weights are relative proportions, numerator over the sum of all values given. A weight of 0 disables that option. Every weight zero throws; negative weights, NaN, and Infinity are invalid.