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0.1.3 Dec 18, 2023
0.1.2 Dec 18, 2023
0.1.1 Dec 17, 2023
0.1.0 Dec 17, 2023

#106 in Programming languages



The Nope Script

Nope is a scripting programming language, optimised for small and fun programs

Nope is

  • Fun
  • Expression based
  • Garbage collected
  • Imperative with a sprinkle of functional
  • Focused on solving practical problems
  • Separates data from logic
  • Can represent JSON and XML natively
  • A single binary
  • Built with Rust
  • Will include a fully featured stdlib
  • Will have an eventloop concurrency model

a screenshot of nope, see samples/fizzbuzz2.nope

Run and Install

Install rust / cargo then

cargo install nope-lang

You can then launch the interactive repl with


Or run a script with

nope myscript.nope

If you use vim you can install syntax support with

nope --install-vim-plugin


This is project is currently at a very very early stage

  • evaluate expressions
  • global, local variables and scopes
  • constant & operators
  • math stdlib
  • loops
  • functions
  • dictionaries and arrays
  • garbage collector
  • errors, try catch
  • string stdlib
  • parsing & serialization
  • utils stdlib
  • resource type
  • os stdlib
  • unit tests
  • v1.0
  • async
  • async stdlib
  • v2.0
  • web server
  • v3.0
  • modules & packages
  • v4.0
  • perf


The following table should give you an idea of the basic types and allowed data models. Keep in mind arrays and objects are not implemented at the moment

    null: null,
    void: [void _ ()]
    bool: [true false]
    num:  [0 1 99 3.14 -1_000_000 0xdead 0b10101 NaN Inf PI]
    string: ['foo' "bar" ~hello]
    arrays: [1 2 true null []]
    dicts:  {key:32 val:99}
    mixed:  ['foo' key:'value']

All data in nope is a combination of the above types and structures.

Note that numbers are 64bit floats, and the strings are unicode.

Code structure

Let's look at basic nope program.

let x = d6() + d6()
var winning = false

if x >= 10 (
    set winning = true
    print 'haha, yes! :)'
) else (
    print 'oh no :('

In the first line, we define a variable called x, with an initial value defined by an expression which calls two functions 'd6' and adds the results. The variable 'x' is available in all subsequent expressions in the current scope. Since it is defined with let, it cannot later be changed with set.

In the second line we declare another variable, but this time it can be modified.

We then evaluate a classic if-else conditional. Note that unlike other languages, the code blocks are not defined by curly braces {/} but by parenthesis (/). The reason is that nope is an expression based language, so every nope construct is an expression that produces a value.

The following example puts those principles in action

let res = if flip_coin(), "heads" else "tails"

The if returns a value, which depending on the result of flip_coin() will be either the string "heads" or "tails".

You can surround expressions with parenthesis, and you can also surround multiple expressions with parenthesis. In the later case, all expressions are evaluated in order, but only the last expression produces a value.

This is what we've used to both change the variable winning with the set winning = true expression, but also to print a message.

Note as well that the print expression print "hey" ommits parenthesis around its argument This is not a special case of the print function. In nope, all parenthesis and commas for functions arguments are optional.

let clamped_0_100 = max 0 min value 100

This is also applies to functions without parameters

let score = d6 + d6 + d6

Note that function application has the highest precedence so print 1 + 1 prints 1 since the addition is performed afterwards. This is not always what you want. One way is to use parenthesis print(1 + 1), print (1 + 1). Note that the space between the function name and the first parenthesis is meaningful. Without space, the full list of arguments is expected, while with the space, it's just parenthesis around a single argument; max(1,2) / max (1) (2)

Another way is to use the left arrow <- operator. This operator simply evaluates the complete expression on the right. So you can do your print like this print <- 1 + 1.

By convention, all functions in nope take the data they operate on as the last argument.

let txt = read_text 'file.txt'
let txt2 = upper txt
write_txt 'file2.txt' txt2

With the help of the left arrow <- operator you could have instead written the following,

write_txt 'file2.txt' <- upper <- read_text 'file.txt'

The right arrow -> operator (not yet implemented) does the same but the other way around.

read_text 'file.txt' -> upper -> write_txt 'file2.txt'


Equality ==, !=

Check that the operands are of the same type, and if that's the case compare their values or references

Comparison <, >, <=, >=

First converts the number to their number equivalent (NaN for strings and arrays) then compares

The +-=and !+-= compare numbers for equality up to EPSILON precision

Arithmetic +, -, *, /, %, **,

The usual math operations. Operands are converted to their number equivalent (NaN for string)

Addition + of a string will perform string concatenation, and convert the other operand to string

Integer & Bitwise Arithmetic

All the arithmetic operators prefixed with ~ will first convert operands to int32 then perform the integer arithmetic operation.

For example 10 ~/ 4 is 2

The bitwise operators ~!, ~|, ~&, ~^, ~<<, ~>>, ~>>> convert the operands to int32 then perform the bitwise operations

Boolean !, ||, &&

The boolean equivalent of an operand is

  • false if null, void or 0
  • true otherwise

The operators

  • ! negates the boolean equivalent
  • && returns the first operand if falsy, otherwise the second
  • || returns the first operand if truthy, otherwise the second

Default ??

Will return the second operand if the first is null or void otherwise the first

Repeat *:

The repeat operator will evaluate and sum the second operand N times, where N is the first operand.

For example, this will throw the dice 3 times

print(3 *: d6)

Note that the first operand is first converted to a number. If the number is zero or negative, we return void.


Nope supports two looping mechanism, loop which endlessly repeats the expression that follows and while, which evaluates a condition and repeats the next expression as long as the condition stays truthy.

var i = 0, while i < 10 (
    set i = print i + 1

continue will jump directly to the next iteration, and break will stop the iteration

var i = 0, loop (
    if i < 10 (
        set i = i + 1

loops are expressions too and return the last value of their expression. break returns void, break_as will break and return the next expression

var i = 0, let res = loop (
    if i < 10 (
        set i = i + 1
    ) else (
        break_as 'done!'

Printing to the terminal

print and echo are similar functions, they take one argument, print the value to the terminal, and returns it. The difference is that print prints the raw string converted value, while echo prints a colored internal representation of the value.

In the repl, each submission is echoed after execution.

Note that since both print and echo return their argument, you can use them inside expressions to display temporary values.

var i = 0, while i < 10 (
    set x = print x + 1

Types check & conversions

The following functions convert to their type, to_num, to_bool, to_str

The following function test the types: is_void, is_null, is_bool, is_num, is_int, is_nan, is_odd, is_even, is_str

Arithmetic Functions and constants

Nope supports the following arithmetic functions

  • floor, ceil, abs, acos, acosh, sin, sinh, asin, asinh, cos, cosh, tan, tanh, atan, atanh, inv log2, log10, ln, ln1p, exp, expm1, sqrt, cbrt, round, fround, trunc, sign, max, min, pow, atan2

And the following arithemtic constants

  • NaN, Inf, PI, E, SQRT_2, SQRT_2PI, LN_2, LN_10, LOG2_10, LOG2_E, LOG10_2, LOG10_E, PHI, TAU, EPISLON, MAX|MIN_INT MAX|MIN_F64, MAX|MIN_I32|16|8, MAX_U32|16|8


  • len returns the length of the string (scans the whole string)
  • upper, lower transform the case of the string
  • trim removes the whitespace at the beginning and end of the string
  • char_at(idx, text) gets the character at string index
  • substr(from_idx, to_idx, text), returns the substring based on character indexes. to_idx is not inclusive. Negative indexes start at the end.
  • replace(from, to, text) replaces the instances of from in text to to
  • find(substr, str), returns the position of substr in str or -1
  • contains(substr, str) returns true if substr is a substring of str
  • bitstr transforms a number to its bitwise representation as a string


Nope supports the following rng functions

  • random, flip_coin, rand100, d4, d6, d8, d10, d12, d20, d100

If you want to return the sum of 3 dice throws it is better to use the repeat operator 3*:d6


Nope allows you to annotate number literal with a unit suffix.

let distance = cos 45deg * (10Km + 3miles + 5yd + 3in + 5cm)

The units convert the number to their SI units equivalent. For example all distances are converted to meters.

The information about the unit of a number is not kept at runtime. Units are nothing more than a convenient syntax trick.

The following units are supported:

pi, tau, phi, GT, MT, kT, T, kg, g, mg, ug, ng, Ti, Gi, Mi, ki, d, h, min, s, ms, us, ns, moon, deg, rad, in, km, m, dm, cm, mm, um, nm, lb, oz, mile, miles, ft, yd, F, C, K, m3, l, dm3, dl, cl, ml, cm3, barrel, cuft, ft3, gal, pint, cuin, in3, cuyd, yd3, m2, dm2, cm2, mm2, a, ha, km2, mile2, yd2, sqyd, ft2, sqft, in2, sqin, belgium, footballfield, TiB, TB, GiB, GB, MiB, MB, KiB, KB, million, billion, trillion, quadrillon, milli, thousandth, micro, nano, pico,

It is also possible to convert from one unit to another at runtime with the from_unit and to_unit functions.

let area_sqin = to_unit 'sqin' <- from_unit 'ha' <- 50


~180K SLoC