Bend/builtins.md

this is a WIP

Built-in Types and Functions

Bend built-in types and functions, this document serves as a reference guide to these built-in features.

Types

String

data String = (Cons head ~tail) | (Nil)

• Nil: Represents an empty string.
• Cons head ~tail: Represents a string with a head character and a tail string.

List

data List = (Cons head ~tail) | (Nil)

• Nil: Represents an empty list.
• Cons head ~tail: Represents a list with a head element and a tail list.

Nat

data Nat = (Succ ~pred) | (Zero)

• Succ ~pred: Represents a natural number successor.
• Zero: Represents the natural number zero.

Result

data Result = (Ok val) | (Err val)

• Ok val: Represents a successful result with value val.
• Err val: Represents an error with value val.

Map

data Map = (Node value ~left ~right) | (Leaf)

• Node value ~left ~right: Represents a map node with a value and left and right subtrees.
• Leaf: Represents an empty map.

Functions

Map

Map/empty

Initializes an empty map.

Map/empty = Map/Leaf

Map/get

Retrieves a value from the map based on the key.

Map/get map key = ...

Map/set

Sets a value in the map at the specified key.

Map/set map key value = ...

IO

IO/Done

Represents a completed IO operation.

IO/Call

Represents a pending IO operation.

IO/MAGIC

Returns a magic number used internally.

def IO/MAGIC: return (0xD0CA11, 0xFF1FF1)

IO/wrap

Wraps a value in an IO/Done.

def IO/wrap(x): return IO/Done(IO/MAGIC, x)

IO/bind

Chains IO operations.

def IO/bind(a, b): match a ...

call

Calls an IO function with an argument.

def call(func, argm): return IO/Call(IO/MAGIC, func, argm, lambda x: IO/Done(IO/MAGIC, x))

print

Prints text to the console.

print text = (IO/Call IO/MAGIC "PUT_TEXT" text @x (IO/Done IO/MAGIC x))

Usage Examples

Map

Map/empty

Initializes an empty map.

Map/empty = Map/Leaf

Map/get

Retrieves a value from the map based on the key.

Map/get map key =
  match map {
    Map/Leaf: (*, map)
    Map/Node:
      switch _ = (== 0 key) {
        0: switch _ = (% key 2) {
          0:
            let (got, rest) = (Map/get map.left (/ key 2))
            (got, (Map/Node map.value rest map.right))
          _:
            let (got, rest) = (Map/get map.right (/ key 2))
            (got, (Map/Node map.value map.left rest))
        }
        _: (map.value, map)
      }
  }

Map/set

Sets a value in the map at the specified key.

Map/set map key value =
  match map {
    Map/Node:
      switch _ = (== 0 key) {
        0: switch _ = (% key 2) {
          0: (Map/Node map.value (Map/set map.left (/ key 2) value) map.right)
          _: (Map/Node map.value map.left (Map/set map.right (/ key 2) value))
        }
        _: (Map/Node value map.left map.right)
      }
    Map/Leaf:
      switch _ = (== 0 key) {
        0: switch _ = (% key 2) {
          0: (Map/Node * (Map/set Map/Leaf (/ key 2) value) Map/Leaf)
          _: (Map/Node * Map/Leaf (Map/set Map/Leaf (/ key 2) value))
        }
        _: (Map/Node value Map/Leaf Map/Leaf)
      }
  }