Expression overview

Some expressions are represented as JSON arrays. The first element is a keyword string that indicates the expression type, and the remaining elements are arguments specific to that expression.

Numeric literals

Numeric literals are represented using strings so they can follow JSON's rules while still allowing Python-style numeric literal forms.

["num", "42"]
["num", "-3.14"]
["num", "1e10"]
["num", "0b1010"]     // binary
["num", "052"]        // octal
["num", "0x2A"]       // hexadecimal
["num", "1_000_000"]  // underscore as digit separator

String literals, booleans and null

These use native JSON values. null maps to None in Calcium.

"Hello, World!"
true  // True
false // False
null  // None

Variable reference

Variable references use the var keyword:

["var", "x"]
["var", "my variable"]

TIP

Variable names may contain any characters valid in JSON strings.

Attribute access

Object attribute access uses the attr keyword:

["attr", ["var", "runtime"], "run"]

The second element is the expression that evaluates to the object, and the third element is the attribute name string.

Subscript access

Indexing into lists or dictionaries uses the sub keyword:

["sub", ["var", "myList"], ["num", "0"]]
["sub", ["var", "myDict"], ["var", "key"]]

Function call

Function calls use the call keyword:

["call", ["var", "print"], [["var", "x"], ["var", "y"]]]

The second element is the expression for the callable, and the third element is an array of argument expressions.

Operators

Operators are represented in prefix form using their corresponding keyword.

["+", ["var", "a"], ["var", "b"]]        // a + b
["-", ["var", "a"], ["var", "b"]]        // a - b
["*", ["var", "a"], ["var", "b"]]        // a * b

Binary operators

The following binary operators are supported.

Operator	Keyword
+	"+"
-	"-"
*	"*"
/	"/"
//	"//"
%	"%"
**	"**"
==	"=="
!=	"!="
<	"<"
<=	"<="
>	">"
>=	">="
and	"and"
or	"or"

Unary operators

The following unary operators are supported.

Operator	Keyword
not	"not"
-	"-_"