Luam

Luam is a modernized fork of Lua 5.1, featuring a stricter, safer, and more concise syntax. It preserves the speed and simplicity of Lua 5.1 while selectively adopting features from later Lua versions and modern programming paradigms.

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Key Features

1. Safer Syntax

Implicit Locals

Variables are local by default, preventing accidental pollution of the global namespace. There is no need to explicitly write local.

x = 10        -- Local variable
function f()  -- Local function
end

Constants

Use the const keyword to define immutable variables. Reassigning a const variable results in a compile-time error.

const y = 20
y = 30 -- Error: attempt to assign to const variable

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2. Modern Operators & Control Flow

Inequality Operator

Use != instead of ~=.

if x != y then
    -- ...
end

Removed Keywords

To simplify the language and enforce a single idiomatic style:

• repeat
• until
• local

have been removed.

All iterative logic is expressed using while loops.

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3. Enhanced String & Data Support

Triple-Quoted Strings

Multiline strings use """ instead of the traditional [[ ... ]] syntax.

s = """
Multi-line
String support
"""

Hexadecimal Escape Sequences

Strings support hexadecimal escapes using \xXX.

"A" == "\x41"

__len Metamethod

Tables support the __len metamethod (backported from Lua 5.2), enabling custom length semantics.

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4. Improved Standard Library

xpcall with Arguments

xpcall accepts arguments passed directly to the called function (backported from Lua 5.2).

xpcall(func, handler, arg1, arg2)

Unified load

load(chunk) handles both functions and strings, replacing the need for loadstring.

Math & Table Enhancements

• math.log(x, base) supports an optional base argument.
• table.pack(...) creates a table from arguments and includes an n field.
• table.unpack(t) is standardized (renamed from unpack).

System & Package Improvements

• os.exit(boolean) supports true for success and false for failure.
• package.searchers is provided as an alias for package.loaders for Lua 5.2 compatibility.

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Build & Install

Luam provides a simplified build process via a dedicated shell script.

Building

chmod +x bld/build_lang.sh
./bld/build_lang.sh

Build artifacts are placed in the bin/ directory:

• bin/luam — Interactive interpreter
• bin/luamc — Bytecode compiler
• bin/sqlite3.so — SQLite3 module

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Documentation

Manual pages are provided in the doc/ directory:

• doc/lua.1
• doc/luac.1

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License

Luam is free software, released under the MIT License, matching Lua 5.1.