In armcn/fp: What the Package Does (One Line, Title Case)

knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>",
  fig.path = "man/figures/README-",
  out.width = "100%"
)

fp

Overview

Functional programming in R.

Installation

You can install the development version from GitHub with:

# install.packages("devtools")
devtools::install_github("armcn/fp")

Usage

Vector functions

library(fp, warn.conflicts = FALSE)

numbers <- 1:10
numbers_list <- as.list(numbers)

map(\(a) a + 1, numbers)

map2(`+`, numbers, numbers)

filter(\(a) a > 5, numbers)

reduce(`+`, 0, numbers)

scan(`*`, 1, numbers)

any(\(a) a %% 2 == 0, numbers)

all(\(a) a %% 2 == 0, numbers)

member(5, numbers)

first(numbers_list)

last(numbers_list)

head(numbers_list)

tail(numbers)

init(numbers)

get_at(3, numbers_list)

Function composition

square <- \(a) a ^ 2
is_even <- \(a) a %% 2 == 0

numbers |> 
  map(square)() |>
  filter(is_even)() |>
  reduce(`+`, 0)()

numbers %|>% 
  map(square) %|>% 
  filter(is_even) %|>% 
  reduce(`+`, 0)

pipe(
  map(square), 
  filter(is_even), 
  reduce(`+`, 0)
)(numbers)

compose(
  reduce(`+`, 0),
  filter(is_even),
  map(square)
)(numbers)

sum_even_squares <- 
  reduce(`+`, 0) %.% 
  filter(is_even) %.%
  map(square)

sum_even_squares(numbers)