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lazyeval

The lazyeval package provides tools that make it easier to correctly implement non-standard evaluation (NSE) in R. You use lazy evaluation by requiring the user to "quote" specially evaluated arguments with ~, and then using the lazyeval package to compute with those formulas. It is also possible to eliminate the use of the ~ by converting promises to formulas. This does make programming with such functions a little harder, but it can be worth it in certain situations. See vignette("lazyeval") for more details.

Installation

Install the released version from CRAN with:

install.packages("lazyeval")

Install the development version from github with:

# install.packages("devtools")
devtools::install_github("hadley/lazyeval", build_vignettes = TRUE)

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Version

Install

install.packages('lazyeval')

Monthly Downloads

579,957

Version

0.2.2

License

GPL-3

Maintainer

Last Published

March 15th, 2019

Functions in lazyeval (0.2.2)

Create a call by "hand"

Interpolate a formula

Convert an object to a lazy expression or lazy dots.

Evaluate a formula

Combine explicit and implicit dots.

Create a function by "hand"

Make a call with lazy_dots as arguments.

Generate a missing argument.

Coerce an object to a name or call.

Display a call (or expression) as a tree.

Get/set formula components.

Find the expression associated with an argument

Turn RHS of formula into a string/label.

Make a promise explicit by converting into a formula.

Is an object a language object?

Capture expression for later lazy evaluation.

Interpolate values into an expression.

Capture ... (dots) for later lazy evaluation.

Is object a formula?

Evaluate a lazy expression.

Modify the arguments of a call.

Automatically name all components of a lazy dots.

Unwrap a formula

Build a named list from the LHS of formulas

Create a formula object by "hand".

Find common environment in list of lazy objects.