#' Build an anonymous function.

#'

#'

#' @param params formal parameters of function, unbound names.

#' @param body substituted body of function to map arguments into.

#' @param env environment to work in.

#' @return user defined function.

#'

#' @seealso \code{\link{lambda}}, \code{\link{defineLambda}}, \code{\link{named_map_builder}}

#'

#' @examples

#'

#' f <- makeFunction_se(as.name('x'), substitute({x*x}))

#' f(7)

#'

#'

#' g <- makeFunction_se(c(as.name('x'), as.name('y')), substitute({ x + 3*y }))

#' g(1,100)

#'

#'

#' @export

#'

makeFunction_se <- function(params, body, env = parent.frame()) {

force(env)

vars <- as.character(params)

formals <- replicate(length(vars), quote(expr = ))

names(formals) <- vars

eval(call('function', as.pairlist(formals), body),

envir = env,

enclos = env)

}

#' Build an anonymous function of dot.

#'

#' @param body function body

#' @param env environment to work in.

#' @return user defined function.

#'

#' @seealso \code{\link{lambda}}, \code{\link{defineLambda}}, \code{\link{named_map_builder}}, \code{\link{makeFunction_se}}

#'

#' @examples

#'

#' f <- f.(sin(.) %.>% cos(.))

#' 7 %.>% f

#'

#'

#' @export

#'

f. <- function(body, env = parent.frame()) {

force(env)

body <- substitute(body)

wrapr::makeFunction_se('.', body, env)

}

#' Build an anonymous function.

#'

#' Mostly just a place-holder so lambda-symbol form has somewhere safe to hang its help entry.

#'

#' @param ... formal parameters of function, unbound names, followed by function body (code/language).

#' @param env environment to work in

#' @return user defined function.

#'

#'

#' @seealso \code{\link{defineLambda}}, \code{\link{makeFunction_se}}, \code{\link{named_map_builder}}

#'

#' @examples

#'

#' #lambda-syntax: lambda(arg [, arg]*, body [, env=env])

#' # also works with lambda character as function name

#' # print(intToUtf8(0x03BB))

#'

#' # example: square numbers

#' sapply(1:4, lambda(x, x^2))

#'

#' # example more than one argument

#' f <- lambda(x, y, x+y)

#' f(2,4)

#'

#'

#' @export

#'

lambda <- function(..., env = parent.frame()) {

force(env)

args <- base::substitute(list(...))

body <- args[[length(args)]]

args <- args[-length(args)]

params <- base::lapply(args[-1], base::as.name)

wrapr::makeFunction_se(params, body, env)

}

#' Define lambda function building function.

#'

#' Use this to place a copy of the lambda-symbol

#' function builder in your workspace.

#'

#' @param envir environment to work in.

#' @param name character, name to assign to (defaults to Greek lambda).

#'

#' @seealso \code{\link{lambda}}, \code{\link{makeFunction_se}}, \code{\link{named_map_builder}}

#'

#' @examples

#'

#' defineLambda()

#' # ls()

#'

#' @export

#'

defineLambda <- function(envir = parent.frame(), name = NULL) {

force(envir)

if(is.null(name)) {

name <- intToUtf8(0x03BB)

}

assign(name, wrapr::lambda, envir = envir)

}