Language Reference

Data types

Type	Example	Notes
number	42, 3.14	Numeric values
text	"hello"	String values
boolean	true, false	Condition values
list	[1, 2, 3]	Ordered values with zero-based indexing

XE is currently dynamically typed. Variables do not carry declared static types, and values use runtime coercions where the language allows them.

Invalid operations now fail with explicit runtime errors instead of silently producing fallback values.

Operators

Arithmetic

• +
• -
• *
• /
• %

Comparison

• ==
• !=
• <
• >
• <=
• >=

Logic

• and
• or
• not

Built-in functions

Function	Purpose	Example
print(...)	Print one or more values	print("hi")
input(prompt)	Read text from the user	name = input("Name? ")
length(value)	Return length of text or list	length([1, 2, 3])
type(value)	Return the XE type name as text	type(42)
convert(value, target)	Convert between supported types	convert("42", "number")

Valid convert targets:

• "number"
• "text"
• "boolean"

Control flow

• if
• elif
• else
• repeat N times
• while
• for name in iterable
• break
• continue

for loops currently iterate over:

• lists
• text values, one character at a time

Function syntax

function name(arg1, arg2):
    return arg1 + arg2

Functions currently use their own local scope. They can access:

• parameters
• variables created inside the function
• built-in functions
• other user-defined functions

They do not capture outer variables from surrounding scopes.

Notes on formatting

• XE uses indentation-based blocks
• spaces are the expected style for indentation
• there are no braces for if, elif, else, repeat, while, for, or function blocks

Assignment semantics

• name = value creates a variable if that name does not exist in any enclosing scope
• otherwise, it reassigns the nearest existing variable instead of creating a shadow copy
• names first created inside a block stay local to that block

Error behavior

• compiler errors include line/column information, the source line, and a caret marker
• invalid runtime operations stop the program with a Runtime error: ... message