Variables
The let
builtin is used to create local variables within the shell, and apply basic arithmetic
to variables. The export
keyword may be used to do the same for the creation of external
variables. Variables cannot be created the POSIX way, as the POSIX way is awkard to read/write
and parse.
let string_variable = "hello string"
let array_variable = [ hello array ]
Multiple Assignments
Ion also supports setting multiple values at the same time
let a b = one two
echo $a
echo $b
let a b = one [two three four]
echo $a
echo @b
Output
one
two
one
two three four
Type-Checked Assignments
It's also possible to designate the type that a variable is allowed to be initialized with.
Boolean type assignments will also normalize inputs into either true
or false
. When an
invalid value is supplied, the assignment operation will fail and an error message will be
printed. All assignments after the failed assignment will be ignored.
let a:bool = 1
let b:bool = true
let c:bool = n
echo $a $b $c
let a:str b[str] c:int d:float[] = one [two three] 4 [5.1 6.2 7.3]
echo $a
echo @b
echo $c
echo @d
Output
true
true
false
one
two three
4
5.1 6.2 7.3
Dropping Variables
Variables may be dropped from a scope with the drop
keyword. Considering that a variable
can only be assigned to one type at a time, this will drop whichever value is assigned to
that type.
let string = "hello"
drop string
let array = [ hello world ]
drop array
Supported Primitive Types
str
: A string, the essential primitive of a shell.bool
: A value which is eithertrue
orfalse
.int
: An integer is any whole number.float
: A float is a rational number (fractions represented as a decimal).
Arrays
The [T]
type, where T
is a primitive, is an array of that primitive type.
Maps
Likewise, hmap[T]
and bmap[T]
work in a similar fashion, but are a collection
of key/value pairs, where the key is always a str
, and the value is defined by the
T
.