hanez/fun

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hanez 436d3ba048 Added spec version 0.1.

2025-09-11 23:24:17 +02:00

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Fun Language Specification v0.1

Fun (Fun Uses Nothing) is a lightweight, multi-purpose programming language designed for clarity, safety, and—above all—fun.

This document defines the language syntax and semantics as of version 0.1.

1. Introduction

Fun is a scripting and systems programming language inspired by the best ideas from C, Lua, and Python—yet deliberately strict in its rules to ensure readability and consistency.

Readable: fixed indentation rules, no ambiguous syntax.
Strict: type safety, no implicit coercion, no silent shadowing.
Hackable: strong system integration with safe defaults.
Fun: simple enough to learn in a day, expressive enough for real work.

2. Lexical Structure

Case Sensitivity

Fun is case-sensitive. Fun and fun are different identifiers.

Identifiers

May contain a–z, A–Z, 0–9, and _.
Must not start with a number.

Keywords

Reserved words cannot be redefined: if, else, for, while, fi, f, global, private, return, true, false.

Comments

Single-line: // This is a comment
Multi-line: /* This is a multi-line comment */

Whitespace

Indentation is exactly two spaces.
Tabs are forbidden.
Line breaks terminate statements (no semicolons).

3. Data Types

Number

64-bit signed integer.

number n = 42

Float

64-bit IEEE floating point.

float pi = 3.14159

String

Double or single quotes may be used.
' has higher priority, so " can appear unescaped inside '...'.
To include ' inside '...', escape with '.

string s1 = "Hello"
string s2 = 'World'
string s3 = "He said: 'Fun!'"

Boolean

Canonical values: true, false.
1 and 0 are accepted in conditionals.

boolean flag = true

Byte

Raw byte value.

byte b1 = 0x23
byte b2 = "A"

Array

Declared using [ ... ].

array nums = [1, 2, 3]

4. Variables and Scope

Global variables: accessible everywhere.
Private variables: file-local, cannot be used outside the file.
Redefining globals or shadowing names is forbidden.

global string message = "Hello"
private number count = 42

5. Operators

Arithmetic: + - * / %
Comparison: == != > < >= <=
Boolean: && || !
Assignment: =

6. Control Flow

If/Else

if(x != y)
  print x
else if(a == b || h != i)
  print a + b
else
  if(k < 1 && l > 1)
    print "Buh!"
  fi
fi

For Loops

for i in range(1, 10)
  print i

While Loops

while x < 10
  print x
  x = x + 1

7. Functions

Internal Functions

Provided by the runtime (cannot be redefined). Examples: print, range, system, exec.

print "Hello, Fun!"

User-Defined Functions

Must be declared with the f prefix.

f add(a, b)
  return a + b

Return Values

Scalars: return a + b
Arrays: return [a, b, c]

8. Modules & Includes

System Includes

Looked up in /var/lib/fun/, supporting .so (native) and .fun (Fun code).

&#35;include crypt/md5
&#35;include date
&#35;include math

Local Includes

From the current working directory:

&#35;include utils/file.fun

Absolute Includes

Full path:

&#35;include /home/user/project/lib.fun

9. System Integration

system

Executes a command, returns exit code.

system("ls -l")

exec

Executes a command, returns stdout.

string result = exec("date")

spawn

Executes a command asynchronously, returns process ID.

number pid = spawn("sleep 10")

10. Error Handling

No implicit type coercion.
Redefinition of globals is a compile-time error.
Using undefined variables or functions is an error.
Internal/runtime functions cannot be shadowed.

11. Examples

Hello World

print "Hello, World!"

Loop with Range

for i in range(1, 5)
  print i

User Function

f greet(name)
  return "Hello " + name

print greet("Fun")

System Call

string now = exec("date")
print "Current time: " + now

12. License

This document and the Fun language reference are licensed under the Apache License 2.0

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