| delay {base} | R Documentation |
delay creates a promise to evaluate the given
expression in the specified environment if its value is requested.
This provides direct access to lazy evaluation mechanism
used by R for the evaluation of (interpreted) functions.
delay(x, env=.GlobalEnv)
x |
an expression. |
env |
an evaluation environment |
This is an experimental feature and its addition is purely for evaluation purposes.
A promise to evaluate the expression.
The value which is returned by delay can be assigned
without forcing its evaluation, but any further accesses
will cause evaluation.
x <- delay({
for(i in 1:7)
cat("yippee!\n")
10
})
x^2 #- yippee
x^2 #- simple number