Topoi lang draft - (1)

-- comments
--| doc comments, should support latex (my dream)
--|prefix| prefixed comments
--[block comment]--
--[prefix| prefixed block comment]--

[1, 2, 3] -- lists
1 :: 2 :: 3 :: [] -- list

-- Types, should starts with uppercase letters
Bool
-- Sum Types
Sum = Bool | Int

a := 123 -- variable assignment (type inferenced)
a : Int = 123 -- variable assginment (with type declarations)

-- Records
record = { a: 32, b: True }

-- Tuples, behaves like a record with numericc field names.
tuples = (32, True)

-- As you see, there is no `let` statement in root level of the file.

-- declare a function
plus2 (x: i32) : i32 = { x + 2 }
plus4 (x: i32) : i32 = plus2 (plus2 x)

-- local variables
plus8 (x: i32) : i32 = {
  let y = plus4 (x) -- (x) can be reduced to x, unless it is (x,)
  let z = plus2 x
  y + z
}

-- yes it is newline sensitive, and I try to avoid semicolon as mandatory
-- because some of the keyboard layouts are hard to type `;`, if they want
-- to make a term multiline, then use parenthesis.

someFunc a b c d e f

-- into

someFunc (
  a       -- there is no comma here, whitespaces or newline is fine
  b
  c
  d
  e
  f
)

-- arrays

-- it is always `[n-ary]type`, so you can make it nested

a : [3][2]Int -- means there is 3 array that contains 2 element of Int
= [[1, 2], [3, 4], [5, 6]]
-- but this is invalid [[1, 2, 3], [4, 5, 6]]

-- random access of data
a : [3][2]i32 = [[1, 2], [3, 4], [5, 6]]
a[1] -- [1, 2]

t := (3, 4)
t.2 -- 4

x = { x: 123, y: True }
x.y -- True

-- closure
\(x:type) (y:type) => body