R: Examples for 'rlang::expr

### ** Examples

# It supports any object. Non-symbolic objects are always printed
# within angular brackets:
expr_print(1:3)

<int: 1L, 2L, 3L>

expr_print(function() NULL)

<function() NULL>

# Contrast this to how the code to create these objects is printed:
expr_print(quote(1:3))

1:3

expr_print(quote(function() NULL))

function() NULL

# The main cause of non-symbolic objects in expressions is
# quasiquotation:
expr_print(expr(foo(!!(1:3))))

foo(<int: 1L, 2L, 3L>)

# Quosures from the global environment are printed normally:
expr_print(quo(foo))

^foo

expr_print(quo(foo(!!quo(bar))))

^foo(^bar)

# Quosures from local environments are colourised according to
# their environments (if you have crayon installed):
local_quo <- local(quo(foo))
expr_print(local_quo)

^foo

wrapper_quo <- local(quo(bar(!!local_quo, baz)))
expr_print(wrapper_quo)

^bar(^foo, baz)

Examples for 'rlang::expr_print'

Print an expression