Variables and Types

Types

merx has three types:

Type	Description	Examples
int	64-bit signed integer	0, 42, -17
str	UTF-8 string	'hello', ''
bool	Boolean	true, false

There are no implicit type conversions. To convert between types, use the as operator (see Type Casting).

String Literals

Strings are enclosed in single quotes:

'Hello, World!'
'merx'
''

Escape Sequences

The following escape sequences are available inside string literals:

Sequence	Meaning
\\'	Single quote
\\\\	Backslash
\\n	Newline (LF)
\\t	Tab
\\r	Carriage return (CR)
\\0	Null character
\\xHH	Hex byte value

A bare \ or ' inside a string is not allowed; you must use the escape sequence.

Example:

flowchart TD
    Start --> A[println 'line1\\nline2']
    A --> B[println 'it\\'s merx']
    B --> End

$ merx run escape.mmd
line1
line2
it's merx

Variables

Assignment

Use = to assign a value to a variable:

flowchart TD
    Start --> A[x = 42]
    A --> B[println x]
    B --> End

$ merx run assign.mmd
42

Dynamic Typing

Variables can hold values of any type, and the type can change on reassignment:

flowchart TD
    Start --> A[x = 42; println x]
    A --> B[x = 'hello'; println x]
    B --> End

$ merx run dynamic.mmd
42
hello

Global Scope

All variables are global. A variable assigned in one node is accessible from any subsequent node:

flowchart TD
    Start --> A[name = 'merx']
    A --> B[println 'Hello, ' + name + '!']
    B --> End

$ merx run scope.mmd
Hello, merx!

Referencing an undefined variable causes a runtime error.

Multiple Statements

You can write multiple statements in a single Process node by separating them with semicolons ;:

flowchart TD
    Start --> A[x = 1; y = 2; println x + y]
    A --> End

$ merx run multi.mmd
3

Statements are executed in order from left to right.

Type Casting

The as operator converts a value to a different type:

expression as type

From	To	Behavior
int	int	No-op
str	int	Parses as decimal. Runtime error on failure
bool	int	Error (not supported)
int	str	Converts to decimal string
str	str	No-op
bool	str	'true' or 'false'

There is no bool cast target in the language.

flowchart TD
    Start --> A[x = 42 as str]
    A --> B[println 'The answer is ' + x]
    B --> C[y = '123' as int]
    C --> D[println y + 1]
    D --> End

$ merx run cast.mmd
The answer is 42
124