A pure function from the full Evidence Model to one field of a
projection's output shape. Must not mutate evidence -- the membrane
defineEvidenceProjection() wraps it in enforces that at runtime, see
createTrackingProxy() below -- and must not perform I/O; data-cap can
enforce the read-only half of purity but not the "no side effects" half.
A pure function from the full Evidence Model to one field of a projection's output shape. Must not mutate
evidence-- the membranedefineEvidenceProjection()wraps it in enforces that at runtime, seecreateTrackingProxy()below -- and must not perform I/O;data-capcan enforce the read-only half of purity but not the "no side effects" half.