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The Rockstar Language Specification

Rockstar is intended to give the programmer an unprecedented degree of poetic license when it comes to the composition and structure of their programs.

File format

Rockstar programs are UTF-8 files with the .rock file extension. (Given that for everything included in the current Rockstar specification, UTF-8 is indistinguishable from 7-bit ASCII, that's a fancy way of saying they're plain text files.)


The use of comments in Rockstar programs is strongly discouraged. This is rock'n'roll; it's up to the audience to find their own meaning. If you absolutely insist on commenting your Rockstar programs, comments should be contained in parentheses (). Yes, this means you can't use brackets in arithmetic expressions and may need to decompose complex expressions into multiple evaluations and assignments.

Rockstar developers are not into that whole brevity thing.

(Initialise Tommy = 1337)
Tommy was a big bad brother. 


There's two ways to declare and use variables in Rockstar.

Common variables consist of one of the keywords a, an, the, my or your followed by a unique variable name, which must contain only lowercase ASCII letters a-z. The keyword is part of the variable name, so a boy is a different variable from the boy.

Proper variables are proper nouns - any word that isn't a reserved keyword and starts with an uppercase letter. Proper variable names can contain spaces as long as each space is followed by an uppercase letter. Whilst some developers may use this feature to create variables with names like Customer ID, Tax Rate or Distance In KM, we recommend you favour idiomatic variable names such as Tommy, Gina, Doctor Feelgood, Mister Crowley, Kayleigh, Tom Sawyer, Billie Jean and Janie.

(Although not strictly idiomatic, Eleanor Rigby, Peggy Sue, Black Betty, Layla and Johnny B Goode would also all be valid variable names in Rockstar.)

As in Ruby, Python and VBScript, variables are dynamically typed and you don't need to declare variables before use.

If a variable is defined outside of a function, it is in global scope. Global scope variables are available everywhere below its first initialization. If a variable is defined inside of a function, it is in local scope. Local scope variables are available from their initialization until the end of the function they are defined in.

While within a function, if you write to a variable that has been defined in global scope, you write to that variable, you do not define a new local variable.


The keywords it, he, she, him, her, they, them, ze, hir, zie, zir, xe, xem, ve, and ver refer to the last named variable determined by parsing order.

(Please don't file issues pointing out that 80s rockers were a bunch of misogynists and gender-inclusive pronouns aren't really idiomatic. You're right, we know, and we've all learned a lot since then. Besides, Look What The Cat Dragged In was recorded by four cishet guys who spent more money on lipgloss and hairspray than they did on studio time, and it's an absolute classic.)


Rockstar uses a similar type system to that defined by the ECMAScript type system, except undefined doesn't sound very rock'n'roll so we use mysterious instead.

  • Mysterious - the value of any variable that hasn't been assigned a value, denoted by the keyword mysterious
  • Null - the null type. Evaluates as equal to zero and equal to false. The keywords nothing, nowhere, nobody, empty and gone are defined as aliases for null
  • Boolean - a logical entity having two values true and false. (The keywords maybe and definitely maybe are reserved for future use)
  • right, yes and ok are valid aliases for true
  • wrong, no and lies are valid aliases for false
  • Number - Numbers in Rockstar are double-precision floating point numbers, stored according to the IEEE 754 standard. (An earlier version of this spec proposed that Rockstar used the DEC64 numeric type. This is a perfect example of something that seemed like a great idea after a couple of beers but turns out to be prohibitively difficult to implement...)
  • String - Rockstar strings are sequences of 16-bit unsigned integer values representing UTF-16 code units.

Functions and function identifiers are not strictly part of the type system in Rockstar 1.0.


The results of comparisons often rely on a concept called 'truthiness'. If the value is truthy, it will be implicitly converted to true. If it is falsy, it will be implicitly converted to false.

  • Mysterious - Falsy
  • Null - Falsy
  • Boolean - Truthy if True, Falsy if False
  • Number - If equal to zero, falsy. Otherwise, truthy.
  • String - Truthy (null is the falsy equivalent)

Constants vs Keywords

Words that are used to construct a literal of a certain type are referred to as constants and words that are used to construct various syntax constructs are referred to as keywords

Constant Aliases
mysterious -
null nothing, nowhere, nobody, empty, gone
true, right, yes, ok
false wrong, no, lies

Literals and Assignment

String literals in Rockstar use double quotes.

  • "Hello San Francisco"

Numeric literals in Rockstar are written as decimal numbers

  • 123
  • 3.141592654

Assignment is denoted by the put/into keyword combination:

  • Put 123 into X will assign the value 123 to the variable X
  • Put "Hello San Francisco" into the message will assign the value "Hello San Francisco" to the variable the message

Single Quotes

Given Rockstar's intriguing ancestral mixture of computer programming, creative English and idiomatic rock'n'roll, the single quote character presents all sorts of challenges.

Most programming languages use the single quote for quoting literal strings - 'like this'. English, when written using the basic ASCII character set, often uses the single quote to stand in for the apostrophe to denote contractions or possessives - you're, she's, he's, shouldn't, rock'n'roll. Rock'n'roll uses the apostrophe apparently at random - sweet child o' mine, ain't talkin' 'bout love, guns n' roses.

Given three such dramatically different influences, here's how Rockstar interprets single quotes.

  1. The sequence 's\W+ - a single quote followed by a lowercase 's' and one or more whitespace characters - should be replaced with is (space, is, space)
  • This allows Janie's got a gun (initialises Janie with the value 313) and Union's been on strike (initialise Union with the value 426) as valid variable declarations.
  1. All other single quotes are then ignored. ain't is equivalent to aint, wakin' has five letters, and ''''' is equal to the empty string. This means you can use single quotes freely throughout your program to punctuate, adjust word lengths and generally channel the spirit of rock'n'roll without worrying about compiler errors.

Increment and Decrement

Increment and decrement are supported by the Build {variable} up and Knock {variable} down statements. Adding more than one up or down in the statement will increment or decrement the same amount of times as you have ups or downs in the statement. There may be a comma between each up and down.

  • Build my world up will increment the value stored in my world by 1.
  • Knock the walls down will decrement the value stored in the walls by 1
  • Knock the walls down, down will decrement the value stored in the walls by 2


Rockstar supports the infix arithmetic operators +, -, * and /. The language includes aliases for each operator so you can write lyrically pleasing expressions.

Operator Operation Aliases
+ addition plus, with
- subtraction minus, without
* multiplication times, of
/ division over

The alias by has been explicitly rejected because of disagreements between the colloquial English ten by four (i.e. 10*4 = 40) and ten (divided) by four (i.e. 10/4 = 2.5)


  • Put the whole of your heart into my hands - multiply your heart by the whole and assign the result to my hands

  • My world is nothing without your love - Initialize my world with the result of subtracting your love from 0

  • If the tears of a child is nothing - check whether the tears * a child = 0

  • My heart over the moon - Returns my heart divided by the moon

Poetic Literals

Rockstar also supports a unique language feature known as poetic literals. Inspired by the here-document syntax supported by many scripting languages, poetic literals allow the programmer to simultaneously initialize a variable and express their innermost angst.

Poetic Constant Literals

A poetic constant literal is a single line consisting of a variable name, the is keyword, or the aliases are, was or were, and a constant signifying the value the variable will be set to.

  • My heart is true - initialises the variable my heart with the Boolean value true
  • Tommy is nobody - initialises the variable Tommy with the value null using the nobody alias
  • Tommy is mysterious - initialises the variable Tommy with the value mysterious.
Poetic String Literals

A poetic string literal assignment starts with a variable name, followed by one of the keywords says followed by a single space. The rest of the line up to the \n terminator is treated as an unquoted string literal.

  • Peter says Hello San Francisco!\n will initialise the variable Peter with the string literal "Hello San Francisco!"
  • San Francisco says Hello back\n will initialise the variable San Francisco with the string literal Hello back

Poetic Number Literals

A poetic number literal begins with a variable name, followed by the keyword is, or the aliases was or were. As long as the next symbol is not a Literal Word, the rest of the line is treated as a decimal number in which the values of consecutive digits are given by the lengths of the subsequent barewords, up until the end of the line. To allow the digit zero, and to compensate for a lack of suitably rock'n'roll 1- and 2-letter words, word lengths are parsed modulo 10. A period (.) character denotes a decimal place. Other than the first period, any non-alphabetical characters are ignored.

  • Tommy was a lovestruck ladykiller initialises Tommy with the value 100
  • Sweet Lucy was a dancer - initialises Sweet Lucy with the value 16
  • A killer is on the loose - initialises a killer with the value 235.
  • My dreams were ice. A life unfulfilled; wakin' everybody up, taking booze and pills - initialises my dreams with the value 3.1415926535
  • Tommy was without initialises Tommy with the value 7 because without is a Reserved Keyword, but not a Literal Word.
  • Note that poetic literals can include Reserved Keywords, as with taking in this example.
  • The semi-colon, comma, apostrophe and any other non-alphabetical characters are ignored.


Similar to the single-equals operator in Visual Basic and some scripting languages, the is keyword in Rockstar is interpreted differently depending whether it appears as part of a statement or as part of an expression. isn't is the logical negation of the is keyword.

Comparison in Rockstar can only be done within an expression.

  • Tommy is nobody initialises the variable Tommy with the value nobody
  • If Tommy is nobody - will execute the following block if, and only if, the variable Tommy is equal to nobody

The keyword ain't (which is reduced to aint by Rockstar) is an alias for isn't. This usage runs contrary to idiomatic English, where "Tommy isn't anybody", "Tommy ain't nobody" and "Tommy ain't not nobody" somehow mean exactly the same thing.

Rockstar also supports the following comparison syntax:

  • is higher/greater/bigger/stronger than to denote 'greater than'
  • is lower/less/smaller/weaker than to denote 'less than'
  • is as high/great/big/strong as to denote 'greater than or equal to'
  • is as low/little/small/weak as to denote 'less than or equal to'

Logical Operations

Rockstar has 4 different logical operators that first convert their operand(s) to a boolean by truthiness.

All logical operators are short circuiting. This means if by evaluating the first argument to the operator guarantees a result, the other argument is not evaluated. false and 1 over 0 is false and does not produce an error for dividing by zero.


Use the Listen keyword to read one line of input from STDIN. Use Listen to to capture the input into a named variable.

  • Listen to your heart - read one line of input from STDIN and store it in your heart

Use the Say keyword to write the value of a variable to STDOUT.

  • Say Tommy - will output the value stored in Tommy to STDOUT

Rockstar defines Shout, Whisper and Scream as aliases for Say

The following examples all use c style syntax for explaining what things do.

Types Continued

Operator Precedence

The higher, the tighter the binding. This is the precedence we generally expect from our math.

  1. Function Call (greedy arguments)
  2. Logical NOT (right-associative)
  3. Multiplication and Division (left-associative)
  4. Addition and Subtraction (left-associative)
  5. Comparison operators (left-associative)
  6. and, or, and nor (left-associative)
  • A taking B times C plus not D times E and F is equivalent to ((A(B) * C) + (!D * E)) && F

Binary Comparison

Equality comparisons (is, ain't, is not) are allowed between types if they are the same type or they can be compared by the rules below. Objects are checked by reference equality, all other types are checked by value equality.

Ordering comparisons (is higher than, is lower than, is as high as, and is as low as) are only allowed if the operands are both Numbers or both Strings or they are converted to such an arrangement according to the rules below. Numbers are compared as expected, Strings are compared lexicographically.

  • <Mysterious> <op> Mysterious => Equal.
  • <Non-Mysterious> <op> Mysterious => Non equal.
  • String <op> Number => Convert the string to a number using base 10 with leading zeros ignored. If it fails, return false.
  • String <op> Boolean => Convert the string to a boolean using all defined aliases.
  • String <op> Null => Non equal.
  • Number <op> Boolean => Convert number to boolean by "truthiness".
  • Number <op> Null => Convert null to 0.
  • Boolean <op> Null => Convert null to false.
  • "1" is 1 evaluates to true because "1" gets converted to the number 1
  • "2" ain't Mysterious evaluates to true because all types are non equal to mysterious, besides mysterious itself.
  • "02" < "10" is true because of the lexicographical comparison between 0 and 1 shows that the first string is less than the second string.
  • True < 10 is an error because 10 gets coerced into True due to the comparison with a boolean and there is no allowed ordering comparisons between booleans.

Increment and Decrement Operators

  • <op> String => Error
  • <op> Boolean => Invert Boolean
  • <op> Null => Error
  • <op> Mysterious => Error

Binary Operators

Conversions other than the listed are errors.

  • String <plus> Number => Convert the number to a base-10 string, retaining all precision, but removing unnecessary digits. A leading zero is considered necessary for numbers with no whole part. eg. 00.1000 gets serialized to 0.1
  • String <plus> Boolean => Convert the boolean to true or false
  • String <plus> Null => Convert the null to null
  • String <plus> Mysterious => Convert the mysterious to mysterious
  • String <times> Number => String gets repeated <Number> times

Flow Control and Block Syntax


Conditional expressions start with the If keyword, followed by an expression. If the expression evaluates to true, then the subsequent code block is executed. Optionally, an Else block can be written after an If block. The code block following the Else keyword would be executed if the If expression evaluated to false.

For the purpose of conditional expressions, 0, mysterious, null, false, and the empty string all evaluate to false, and everything else to true.


Similar to the If statement, a loop is denoted by the While or Until keyword, which will cause the subsequent code block to be executed repeatedly whilst the expression is satisfied:

Tommy was a dancer
While Tommy ain't nothing,
Knock Tommy down

That'll initialize Tommy with the value 16 (using the poetic number literal syntax) and then loop, decrementing Tommy by 1 each time until Tommy equals zero (i.e ain't nothing returns false).

The break and continue statements work as they do in most block-based languages. Rockstar defines Break it down as an alias for break and Take it to the top as an alias for continue


A block in Rockstar starts with an If, Else, While or Until statement, and is terminated by a blank line or the end-of-file. EOF ends all open code blocks

Tommy was a dancer
While Tommy ain't nothing
Shout it
Knock it down


Functions are declared with a variable name followed by the takes keyword and a list of arguments separated by one of the following: and , & , and 'n'

  • Multiply takes X and Y
  • Search takes Needle and Haystack

The function body is a list of statements with no separating blank lines. A blank line denotes the end of a function body. Functions in Rockstar always have a return value, indicated by the Give back keyword.

Functions are called using the 'taking' keyword and must have at least one argument. Multiple arguments are separated with one of the following: , & , and 'n'.

Arguments may only be variables or literals. Compound expressions are not allowed. Functionals are greedy, if they find more symbols that make up valid arguments they will take them.

  • Multiply taking 3, 5 is an expression returning (presumably) 15
  • Search taking "hands", "lay your hands on me"
  • Put Multiply taking 3, 5, and 9 into Large will set large to 3 * 5 * 9 NOT (3 * 5) && 9.