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

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.

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

Arguments

...: Additional arguments passed to Future().
envir: The environment from where global objects should be identified.

Value

A SequentialFuture.

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)
#> [1] 7

v <- value(f)
print(v)
#> [1] 0
stopifnot(v == 0)