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---
title: Variable declaration
version: 1.0.0
state: draft
---
# Variable declaration
## Terms
list: multiple tokens seperated by spaces
token: a particular fully formed symbol or set of symbols representing a specific meaning in rabbitscript and that has no more specific underlying meaning. (i.e. a VARNAME is a token but not an EXPRESSION, however a LITERAL or an OPERAND are tokens)
meaning: something that a parser of the grammar could act on to verify syntaxic validity (is a token valid in relation to the token that follows or precedes it)
representation: something that defines meaning and that a parser of the grammar could act on to verify a token's validity (is a token properly represented or does it contain a symbol that breaks the validity of its representation)
## Grammar
### Declaration
```
VARNAME = EXPRESSION
```
### VARNAME
A VARNAME is represented by a series of alphanumeric characters:
```
alphanum+
```
### EXPRESSION
```
(OPERATION | LITERAL)
```
### LITERAL
A literal is represented by a set of alphanumeric symbols. If the symbols can be parsed as a number then the type is a number, otherwise it is a a string.
```
(number|string)
```
### OPERATION
Operations are calculations on numbers using reverse polish notation.
An operation is defined as a list of n operands (where n>1) followed by a a list of n-1 operators, or otherwise said an operand followed by n>=1 operands followed by n operators:
```
OPERAND (OPERAND ){N} OPERATOR{N}
```
An operand is defined strictly as a number (integer or floating). An operator is defined by the addition, subtraction, multiplication and division symbols as follows:
```
(+|-|*|/)
```
## Example
Declares a variable `a` with the number value 15.
```
a=15
```
Declares a variable `b` with the string value "a string".
```
s=a string
```
Declares the variable `o` that is an operation resulting in the number value 6.
```
o=1 5 +
```
The same as above can be specified with an arbitrary number of spaces around the tokens. They should be trimmed by parsers:
```
o = 1 5 +
```
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