future (version 1.30.0)

sequential: Create a sequential future whose value will be in the current R session

Description

A sequential future is a future that is evaluated sequentially in the current R session similarly to how R expressions are evaluated in R. The only difference to R itself is that globals are validated by default just as for all other types of futures in this package.

Usage

sequential(..., envir = parent.frame())

Value

A SequentialFuture.

Arguments

...

Additional arguments passed to Future().

envir

The environment from where global objects should be identified.

Details

This function is not meant to be called directly. Instead, the typical usages are:

# Evaluate futures sequentially in the current R process
plan(sequential)

Examples

## Use sequential futures
plan(sequential)

## A global variable
a <- 0

## Create a sequential future
f <- future({
  b <- 3
  c <- 2
  a * b * c
})

## Since 'a' is a global variable in future 'f' which
## is eagerly resolved (default), this global has already
## been resolved / incorporated, and any changes to 'a'
## at this point will _not_ affect the value of 'f'.
a <- 7
print(a)

v <- value(f)
print(v)
stopifnot(v == 0)