Synonym for Stdlib.Lazy.Undefined.

Represents a deferred computation of suspension.

from_val value returns an already forced suspension whose result is the given value.

from_fun fn returns a suspension.

force t forces the suspension, i.e. computes fn () using the fn passed to from_fun, stores the result of the computation to the suspension and reproduces its result. In case the suspension has already been forced the computation is skipped and stored result is reproduced.

• raises Undefined

  in case the suspension is currently being forced by the current promise.