The Elk Shell Language

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Variables ​

Declaration ​

Variables have to be declared before being used, and can contain values of any data type. Regular variables are not treated as environment variables. The syntax for declarations is the following:

elk
let variableName = value
let x, y = (2, 3) # tuple deconstruction syntax
let variableName = value
let x, y = (2, 3) # tuple deconstruction syntax

INFO

Variables are accessible only from within the scope they were created in, including child scopes. Shadowing of variables is possible, meaning a variable can be declared with the same name as a pre-existing variable in the same scope. If it declared in a child scope of the pre-existing variable, it is treated as a separate variable within that scope.

Usage ​

Variables are accessed by typing their name. Unlike in Bash, it is not necessary to use a prefix (eg. $) when accessing variables in Elk. The following operations can be used to update the value of a variable:

OperationSymbol
Assignment=
Add to value+=
Subtract from value-=
Divide value/=
Multiply value*=
Assign value if nil??=
Raise value to power^
elk
let variableName = 1 # value is 1
variableName = 2     # value is 2
variableName += 1    # value is 3
let variableName = 1 # value is 1
variableName = 2     # value is 2
variableName += 1    # value is 3

Environment Variables ​

Environment variables can be created and accessed by putting a dollar sign in front of the variable name. Any variable name with a leading dollar sign is treated as an environment variable. Naturally, this means that these types of variables can only be assigned string values. An environment variable can be assigned to with or without the let keyword.

elk
let $ENV_VAR = "hello"
echo($ENV_VAR)
$ENV_VAR += " world"
let $ENV_VAR = "hello"
echo($ENV_VAR)
$ENV_VAR += " world"

TIP

The $? variable is automatically set to the exit code of the last executed program.