---
title: "If"
author: "Colin Fay"
date: "`r Sys.Date()`"
output: rmarkdown::html_vignette
vignette: >
  %\VignetteIndexEntry{If}
  %\VignetteEngine{knitr::rmarkdown}
  %\VignetteEncoding{UTF-8}
---

```{r setup, include = FALSE}
knitr::opts_chunk$set(
  error = TRUE,
  collapse = TRUE,
  comment = "#>"
)
library(attempt)
```

## `if_` conditions

`if_none()`, `if_any()` and `if_all()` test the elements of the list. 

```{r eval=TRUE}
if_all(1:10, ~ .x < 11, ~ return(letters[1:10]))

if_any(1:10, is.numeric, ~ "Yay!")

if_none(1:10, is.character, ~ rnorm(10))
```

The defaut for all `.p` is `isTRUE()`. So you can: 

```{r eval=TRUE}
a <- c(FALSE, TRUE, TRUE, TRUE)

if_any(a, .f = ~ "nop!")
```

`if_then()` performs a simple "if this then do that":

```{r eval=TRUE}
if_then(1, is.numeric, ~ "nop!")
```

`if_not()` runs `.f` if `.p(.x)` is not TRUE : 

```{r eval = TRUE}
if_not(.x = 1, .p = is.character, ~ ".x is not a character")
```

And `if_else()` is a wrapper around `base::ifelse()`. 

If you want these function to return a value, you need to wrap these values into a mapper / a function. E.g, to return a vector, you'll need to write `if_then(1, is.numeric, ~ "Yay")`.

```{r eval=TRUE}
a <- if_else(1, is.numeric, ~ "Yay", ~ "Nay")
a
```