Cassette Primitives

This is the reference of built-in primitives for the programming language Cassette.

Built-in functions are executed via the trap keyword. These trap calls are usually wrapped in a module function at runtime for convenience. For example:

def print(value) trap print(value)

System Functions

panic!(message)

Halts the program in an error state, with the given message.

typeof(value)

Returns the type of the given value, as a symbol:

• :integer
• :symbol
• :pair lists, pairs, and nil
• :tuple
• :binary

char(num)

Returns a string of length 1, with the byte value of num (which must be between 0 and 255).

format(iodata)

Renders iodata into a binary. iodata is a binary, an integer between 0–255 (representing a byte), or a list of other iodata items.

symbol_name(symbol)

Returns a string of the name of the given symbol, or nil if not present.

hash(value)

Returns a hash of a value.

popcount(num)

Returns the number of bits set in an integer.

max_int()

Returns the maximum integer.

min_int()

Returns the minimum integer.

time(value)

Returns the current Unix timestamp, in seconds.

random()

Returns a random integer between the minimum and the maximum integer size.

seed(value)

Seeds the random number generator.

I/O

open(path, flags)

Wrapper for the Unix open function. Returns a file descriptor as an integer or {:error, reason}.

open_serial(device, speed, opts)

Opens a serial device. opts is an integer that is set to the c_cflag property of the termios. Returns a file descriptor as an integer or {:error, reason}.

close(file)

Wrapper for the Unix close function. Returns :ok or {:error, reason}.

read(file, size)

Wrapper for the Unix read function. Returns a binary or {:error, reason}.

write(file, data, size)

Wrapper for the Unix write function. Returns the number of bytes written or {:error, reason}.

seek(file, offset, whence)

Wrapper for the Unix lseek function. Returns the position or {:error, reason}.

listen(port)

Returns a passive socket listening on a given port (as a string).

accept(socket)

Waits for a new connection on a passive socket.

connect(host, port)

Returns an active socket connected to a host and port.

Graphics

open_window(title, width, height)

Creates a new window. Returns a window reference.

close_window(window)

Closes a window.

update_window(window)

Updates a window's contents.

next_event()

Returns an event record with these fields:

• what: Event type, one of :keyDown, :keyUp, :autoKey, :mouseDown, :mouseUp, or :quit.
• when: Timestamp of when the event occured.
• where: The mouse position of the event, as a point record with x and y fields.
• message: The event message. For keyboard events, this is the ASCII character in the low byte and the scan code in the second byte. For mouse events, this is a window reference.
• modifiers: A bitmap of keyboard modifiers.

   15   13 12 11 10  9  8  7  6        0
  ┌───────┬──┬──┬──┬──┬──┬──┬───────────┐
  │       │  │  │  │  │  │  │           │
  └───────┴─┬┴─┬┴─┬┴─┬┴─┬┴─┬┴───────────┘
  Control───┘  │  │  │  │  │
  Option───────┘  │  │  │  │
  Caps Lock───────┘  │  │  │
  Shift──────────────┘  │  │
  Command───────────────┘  │
  Mouse────────────────────┘
  

write_pixel(x, y, color, window)

Writes a pixel into a window. Color is a 24-bit 0x00RRGGBB integer.

blit(data, width, height, x, y, window)

Copies pixel data into a window. data is a binary of pixel values, width and height are the size of the source image, and x and y are the destination in the window.