Module IO.Sampling

Return one finite draw greater than or equal to zero and less than one. The core validates the result and contains ordinary exceptions. Runtime composition owns concrete randomness.

Allocate a fresh unresolved one-shot draw without invoking the random source or performing concrete I/O.

Resolve that draw at most once. Concurrent callers receive the same result without invoking the source more than once. A source exception is replayed with its original backtrace. Core contains and diagnoses ordinary source failures while preserving runtime control exceptions.