AST.hs

module AST where

import Data.Constraint
import Data.Functor.Compose
import Data.Fix
import Data.Text (Text)
import qualified Data.Text as Text

import GHC.TypeLits

newtype Root carrier ph w = Root { unRoot :: Fix (Compose w (carrier ph w)) }

type AST = Root AST_

data AST_ (ph :: k) w self where
  Var   :: Name                                        -> AST_ ph w self
  App   :: self                 -> [self]              -> AST_ ph w self
  Lam   :: [w (Param ph w)]     ->  self               -> AST_ ph w self
  Let   :: [w (Decl ph w self)] ->  self               -> AST_ ph w self
  Match :: self                 -> [w (Alt ph w self)] -> AST_ ph w self
  Const :: Constant                                    -> AST_ ph w self
  BIF   :: Builtin                                     -> AST_ ph w self

data Param ph w = Param Name (w (Type ph w))

type Type = Root Type_

data Type_ ph w self
  = TConst Name
  | TRigid Name
  | TVar   Name
  | TArr   self self
  | TApp   self self
  | Forall Name self self
  | U
  | TypedHole

data Constant
  = I Integer
  | S String

data Builtin = Builtin
  { bifName  :: Name
  , bifArity :: Integer
  }

data Decl ph w ast
  = Def  (w (Param ph w)) ast
  | Data (w (Param ph w)) [w (Ctor ph w)]

data Ctor ph w = Ctor Name [w (Param ph w)] (w (Type ph w))

data Alt ph w ast
  = Alt (w (Pattern ast ph w)) ast

type Pattern ast = Root (Pattern_ ast)

data Pattern_ ast ph w self
  = IsHole  Name
  | IsView  ast    self
  | IsCtor  Name  [self]
  | IsConst Constant
  | IsWildcard

newtype Name = Name Text

gistfile1.txt

name: adadsa

version: 1.0.0

dependencies:
- base
- constraints
- data-fix
- free
- exceptions
- mtl
- text

default-extensions:
- GADTs
- BlockArguments
- DataKinds
- RankNTypes
- TypeOperators
- MultiParamTypeClasses
- AllowAmbiguousTypes
- TypeFamilies
- UndecidableInstances
- ConstraintKinds
- FlexibleContexts
- TypeApplications
- ScopedTypeVariables
- FlexibleInstances
- DefaultSignatures
- QuantifiedConstraints
- LambdaCase
- DerivingStrategies
- DeriveAnyClass
- StandaloneDeriving
- PolyKinds

library:
  source-dirs:
  - .