## ----setup, include = FALSE---------------------------------------------------
knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>",
  eval = FALSE
)

library(rlang)
fail <- function() "\u274c"
pass <- function() "\u2705"

## -----------------------------------------------------------------------------
# bar(foo(x))

## -----------------------------------------------------------------------------
# local({
#   . <- x
#   . <- foo(.)
#   bar(.)
# })

## -----------------------------------------------------------------------------
# local({
#   ...1 <- x
#   ...2 <- foo(...1)
#   bar(...2)
# })

## -----------------------------------------------------------------------------
# with_dot_cleanup <- function(expr) {
#   # Initialises `.` in the caller environment and resets it on exit.
#   # (We use `:=` instead of `=` to avoid partial matching.)
#   rlang::local_bindings(. := NULL, .env = parent.frame())
#   expr
# }
# with_dot_cleanup({
#   . <- x
#   . <- foo(.)
#   bar(.)
# })

## -----------------------------------------------------------------------------
# mask1 <- new.env(parent = env)
# mask2 <- new.env(parent = env)
# 
# delayedAssign(".", x, mask1)
# delayedAssign(".", foo(.), mask2)
# with(mask2, bar(.))

## -----------------------------------------------------------------------------
# local({
#   delayedAssign("...1", x)
#   delayedAssign("...2", foo(...1))
#   bar(...2)
# })

## -----------------------------------------------------------------------------
# delayedAssign("...1", x)
# delayedAssign("...2", foo(.))
# bar(...2)

## -----------------------------------------------------------------------------
# sample(10) %>% list(., .)
# 
# # Becomes
# list(sample(10), sample(10))

## -----------------------------------------------------------------------------
# sample(10) %>% foo(., .)
# foo(. <- sample(10), .)

## ----eval = TRUE--------------------------------------------------------------
`%|>%` <- magrittr::pipe_nested

## ----eval = TRUE, error = TRUE------------------------------------------------
try({
"foo" %|>% list(., .)
})

## ----eval = TRUE--------------------------------------------------------------
{
  stop("oh no") %|>% try(silent = TRUE)
  "success"
}

## ----eval = TRUE--------------------------------------------------------------
factory <- function(x) function() x
fn <- factory(TRUE)
fn()

## -----------------------------------------------------------------------------
# fn <- TRUE %|>% factory()
# fn()

## -----------------------------------------------------------------------------
# faulty <- function() stop("tilt")
# f <- function(x) x + 1
# g <- function(x) x + 2
# h <- function(x) x + 3
# 
# faulty() %|>% f() %|>% g() %|>% h()
# #> Error in faulty() : tilt
# 
# traceback()
# #> 7: stop("tilt")
# #> 6: faulty()
# #> 5: f(faulty())
# #> 4: g(f(faulty()))
# #> 3: h(g(f(faulty())))
# #> 2: .External2(magrittr_pipe) at pipe.R#181
# #> 1: faulty() %|>% f() %|>% g() %|>% h()

## ----eval = TRUE--------------------------------------------------------------
foo <- FALSE
TRUE %|>% assign("foo", .)
foo

## ----eval = TRUE--------------------------------------------------------------
fn <- function() {
  TRUE %|>% return()
  FALSE
}
fn()

## -----------------------------------------------------------------------------
# options(error = rlang::entrace)

## -----------------------------------------------------------------------------
# foobar <- function(x) x %|>% quux()
# quux <- function(x) x %|>% stop()
# 
# "tilt" %|>% foobar()
# #> Error in x %|>% stop() : tilt
# 
# rlang::last_trace()
# #> <error/rlang_error>
# #> tilt
# #> Backtrace:
# #>     █
# #>  1. ├─"tilt" %|>% foobar()
# #>  2. └─global::foobar("tilt")
# #>  3.   ├─x %|>% quux()
# #>  4.   └─global::quux(x)
# #>  5.     └─x %|>% stop()

## ----eval = TRUE--------------------------------------------------------------
`%!>%` <- magrittr::pipe_eager_lexical

## ----eval = TRUE--------------------------------------------------------------
"foo" %!>% list(., .)

## ----eval = TRUE, error = TRUE------------------------------------------------
try({
{
  stop("oh no") %!>% try(silent = TRUE)
  "success"
}
})

## ----eval = TRUE--------------------------------------------------------------
fn <- TRUE %!>% factory() %!>% { .() }
fn()

## ----eval = TRUE, error = TRUE------------------------------------------------
try({
fn <- TRUE %!>% factory()
fn()
})

## ----eval = TRUE--------------------------------------------------------------
. <- "wrong"
fn <- TRUE %!>% factory()
fn()

## -----------------------------------------------------------------------------
# faulty <- function() stop("tilt")
# f <- function(x) x + 1
# g <- function(x) x + 2
# h <- function(x) x + 3
# 
# faulty() %!>% f() %!>% g() %!>% h()
# #> Error in faulty() : tilt
# 
# traceback()
# #> 4: stop("tilt")
# #> 3: faulty()
# #> 2: .External2(magrittr_pipe) at pipe.R#163
# #> 1: faulty() %!>% f() %!>% g() %!>% h()

## ----eval = TRUE--------------------------------------------------------------
foo <- FALSE
NA %!>% { foo <- TRUE; . }

foo

## ----eval = TRUE--------------------------------------------------------------
fn <- function() {
  TRUE %!>% return()

  FALSE
}
fn()

## ----eval = TRUE--------------------------------------------------------------
`%?>%` <- magrittr::pipe_lazy_masking

## ----eval = TRUE--------------------------------------------------------------
"foo" %?>% list(., .)

## ----eval = TRUE--------------------------------------------------------------
{
  stop("oh no") %?>% try(silent = TRUE)
  "success"
}

## ----eval = TRUE--------------------------------------------------------------
fn <- TRUE %?>% factory()
fn()

## -----------------------------------------------------------------------------
# faulty <- function() stop("tilt")
# f <- function(x) x + 1
# g <- function(x) x + 2
# h <- function(x) x + 3
# 
# faulty() %?>% f() %?>% g() %?>% h()
# #> Error in faulty() : tilt
# 
# traceback()
# #> 7: stop("tilt")
# #> 6: faulty()
# #> 5: f(.)
# #> 4: g(.)
# #> 3: h(.)
# #> 2: .External2(magrittr_pipe) at pipe.R#174
# #> 1: faulty() %?>% f() %?>% g() %?>% h()

## ----eval = TRUE--------------------------------------------------------------
foo <- FALSE
TRUE %?>% assign("foo", .)
foo

## ----eval = TRUE, error = TRUE------------------------------------------------
try({
fn <- function() {
  TRUE %?>% return()
  FALSE
}
fn()
})

## -----------------------------------------------------------------------------
# foobar <- function(x) x %?>% quux()
# quux <- function(x) x %?>% stop()
# 
# "tilt" %?>% foobar()
# #> Error in x %?>% stop() : tilt
# 
# rlang::last_trace()
# #> <error/rlang_error>
# #> tilt
# #> Backtrace:
# #>     █
# #>  1. ├─"tilt" %?>% foobar()
# #>  2. ├─global::foobar(.)
# #>  3. │ └─x %?>% quux()
# #>  4. └─global::quux(.)
# #>  5.   └─x %?>% stop()