delay {base}

R Documentation

Delay Evaluation

Description

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.

Usage

delay(x, env=.GlobalEnv)

Arguments

x	an expression.
env	an evaluation environment

Details

This is an experimental feature and its addition is purely for evaluation purposes.

Value

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.

Examples

x <- delay({
    for(i in 1:7)
        cat("yippee!\n")
    10
})

x^2#- yippee
x^2#- simple number

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