The  syntax in Ion denotes that the contents within should be parsed as an
let keyword for array variables, all array arguments must be wrapped within the  syntax. Otherwise it will be coerced into a space-separated string.
This design decision was made due to the possibility of an expanded array with one element
being interpreted as a string.
Once created, you may call an array variable in the same manner as a string variable, but you must use the @ sigil instead of $. When expanded, arrays will be expanded into multiple arguments. Hence it is possible to use arrays to set multiple arguments in commands.
NOTE If an array is double quoted, it will be coerced into a string. This behavior is equivalent to invoking the
NOTE: Brace expansions also create arrays.
Arguments enclosed within brackets are treated as elements within an array.
let array = [ one two 'three four' ]
Values can be fetched from an array via their position in the array as the index.
let array = [ 1 2 3 4 5 ] echo @array echo @array[2..=4]
1 3 4 5
Passing an array within brackets enables performing a deep copy of that array.
let array = [ 1 2 3 ] let array_copy = [ @array ] echo @array_copy
1 2 3
This will join each element of the array into a string, adding spaces between each element.
let array = [ hello world ] let other_array = [ this is the ion ] let array = [ @array @other_array shell ] let as_string = @array echo @array echo $as_string
hello world this is the ion shell hello world this is the ion shell
::= operators can be used to efficiently concatenate an array in-place.
let array = [2 3] let array ++= [4 5] # append let array ::= [0 1] # append before beginning [0 1] let array \\= [2 3] # remove variables 2 and 3 echo @array let array ++= 6 # same with single variables let array ::= -1 let array \\= 0 echo @array
0 1 4 5 -1 1 4 5 6
Passing arrays as command arguments and capturing output of commands as arrays is useful.
mkdir -p _tmp _tmp/t1 _tmp/t2 cd _tmp let args = [-a --file-type] ls @args # use args as arguments for command ls let res = [ @(ls) ] # get result of ls as array res echo @res # output the array res cd .. rm -fr _tmp
./ ../ t1/ t2/ t1 t2