lowkPRO

Full Windows API in Lua

• Use Windows C APIs with vanilla Lua 5.5
• Functions, structs/unions, callbacks, arrays
• Seamless C <—> Lua type conversions

Conveniences for common tasks

• registerhotkey('ctrl alt d', myfn)
• sendkeys'lwin e'
• And more!

File association for quick apps

Associates .lowk files with lowkPRO so you can create Windows applications on the fly. Just type some Lua code, save it, and you're done!

Purchase

Documentation

The full power of the Windows C API is available to the Lua script in any .lowk file.

All functions, constants, and types, and many macros, are available as globals.

1. Create a .lowk file
2. Write Lua code
3. Double-click it

Hello world

local b = MessageBox(
  nil, "❤️?", "hi", MB_YESNO)

print(b, b == IDYES, b == IDNO)
os.execute('pause')

6       true    false
Press any key to continue . . .

Lua to C primitive mapping

Type constructors

Create structs, unions, and typedefs like so:

• TYPE()
  Returns sizeof(TYPE) memory
• TYPE[n]
  Returns sizeof(TYPE)*n memory
• #TYPE
  Returns sizeof(TYPE)

All memory is zeroed and garbage collectable.

CHAR[200]  -- returns 200 bytes
BOOL[3]    -- returns 12 bytes
WNDCLASS() -- returns 72 bytes
#WNDCLASS  -- returns 72

Type accessors

Get or set fields on structs or unions like so:

• mem[n]
  Returns mem[n] based on mem's TYPE
• mem.field
  Returns mem->field
• mem.field=val
  Sets mem->field=val
• TYPE.get_[field](mem)
  Returns mem->[field]
• TYPE.set_[field](mem, val)
  Sets mem->[field]=val

Callbacks

• CALLBACKTYPE(luafn) -> void*
  Returns C function pointer as userdata

local ptr =
  WNDENUMPROC(function(hwnd, data)
    print(hwnd)
    return true
  end)

print(ptr)
-- WNDENUMPROC: 000001AA1D100000

Additional globals

• hInstance, hPrevInst, pCmdLine, nCmdShow passed on from winmain
• handleerror(e) global error handler if set
• print(...) opens a new console
• printf(...) just like in C
• L(str) creates wide-char userdata
• memtostr(mem) makes lua zstring of mem
• memtostr(mem,sz) same but str with size

Unicode support

UTF-8 is enabled for ANSI functions. This works automatically with Lua strings.

When calling wide-char functions, use the L() helper to create unicode WCHAR* strings.

All ANSI functions with an A-suffix are aliased without it, so MessageBox==MessageBoxA.

Sample run loop

local msg = MSG()
while true do
  Sleep(1)
  GetMessage(msg, nil, 0, 0)
  TranslateMessage(msg)
  DispatchMessage(msg)
end

Changelog

1.0-rc1 (10/23/2025)

• All the features
• All the bugs
• Some of the TODOs

Name meaning

The name "lowkPRO" is an acronym, short for "Lua on Windows kernel for professionals."

Contact

For all inquiries, email contact@lowkpro.com