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daitai-lang quick reference

This is the one-page summary. For the normative specification, see the v1.4 spec.

Keywords

class    interface   enum        function    method
static   return      if          else        for
in       while       match       case        val
this     import      module      implements  extends

Algebraic keywords (v1.2+)

MONOID  GROUP  RING  SEMIRING  LATTICE  CATEGORY
FUNCTOR APPLICATIVE MONAD COMONAD FREEMONAD ARROW
NATURALTRANSFORM COALGEBRA YONEDA ADJUNCTION GALOIS
TOPOS OPERAD MONOIDALCATEGORY ENRICHEDCATEGORY

Literals

42              -- Int
3.14            -- Float
true, false     -- Bool
"hello"         -- String
None            -- Optional<T> (empty)
Some(x)         -- Optional<T> (with value)
/pattern/flags  -- Regex
|0⟩, |1⟩, ⟨ψ|   -- bra-ket (v1.3+)

Effects

There are no exceptions. Failable operations return Result<T, E>:

function parseInt(s: String) -> Result<Int, ParseError>

There are no null pointers. Absence is Optional<T>:

function find(xs: List<T>, p: T -> Bool) -> Optional<T>

There is no implicit mutation. Mutation lives behind a Step:

function tick(state: GameState, dt: Duration) -> GameState =
  Step(state, .player.position, dt * state.player.velocity)

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