{-|
Module      : Idris.Elab.Provider
Description : Code to elaborate type providers.

License     : BSD3
Maintainer  : The Idris Community.
-}
{-# LANGUAGE PatternGuards #-}
module Idris.Elab.Provider(elabProvider) where

import Idris.AbsSyntax
import Idris.Core.Evaluate
import Idris.Core.Execute
import Idris.Core.TT
import Idris.Core.Typecheck
import Idris.Delaborate
import Idris.Docstrings
import Idris.Elab.Clause
import Idris.Elab.Term
import Idris.Elab.Type
import Idris.Elab.Value
import Idris.Error
import Idris.Options
import Idris.Providers

import Prelude hiding (id, (.))

import Control.Category
import Control.Monad

-- | Elaborate a type provider
elabProvider :: Docstring (Either Err PTerm) -> ElabInfo -> SyntaxInfo -> FC -> FC -> ProvideWhat -> Name -> Idris ()
elabProvider :: Docstring (Either Err PTerm)
-> ElabInfo
-> SyntaxInfo
-> FC
-> FC
-> ProvideWhat
-> Name
-> Idris ()
elabProvider doc :: Docstring (Either Err PTerm)
doc info :: ElabInfo
info syn :: SyntaxInfo
syn fc :: FC
fc nfc :: FC
nfc what :: ProvideWhat
what n :: Name
n
    = do IState
i <- Idris IState
getIState
         -- Ensure that the experimental extension is enabled
         Bool -> Idris () -> Idris ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
unless (LanguageExt
TypeProviders LanguageExt -> [LanguageExt] -> Bool
forall (t :: * -> *) a. (Foldable t, Eq a) => a -> t a -> Bool
`elem` IState -> [LanguageExt]
idris_language_extensions IState
i) (Idris () -> Idris ()) -> Idris () -> Idris ()
forall a b. (a -> b) -> a -> b
$
           String -> Idris ()
forall a. String -> Idris a
ifail (String -> Idris ()) -> String -> Idris ()
forall a b. (a -> b) -> a -> b
$ "Failed to define type provider \"" String -> String -> String
forall a. [a] -> [a] -> [a]
++ Name -> String
forall a. Show a => a -> String
show Name
n String -> String -> String
forall a. [a] -> [a] -> [a]
++
                   "\".\nYou must turn on the TypeProviders extension."

         Context
ctxt <- Idris Context
getContext

         -- First elaborate the expected type (and check that it's a type)
         -- The goal type for a postulate is always Type.
         (ty' :: Term
ty', typ :: Term
typ) <- case ProvideWhat
what of
                         ProvTerm ty :: PTerm
ty p :: PTerm
p   -> ElabInfo -> ElabMode -> PTerm -> Idris (Term, Term)
elabVal ElabInfo
info ElabMode
ERHS PTerm
ty
                         ProvPostulate _ -> ElabInfo -> ElabMode -> PTerm -> Idris (Term, Term)
elabVal ElabInfo
info ElabMode
ERHS (FC -> PTerm
PType FC
fc)
         Bool -> Idris () -> Idris ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
unless (Term -> Bool
isTType Term
typ) (Idris () -> Idris ()) -> Idris () -> Idris ()
forall a b. (a -> b) -> a -> b
$
           String -> Idris ()
forall a. String -> Idris a
ifail ("Expected a type, got " String -> String -> String
forall a. [a] -> [a] -> [a]
++ Term -> String
forall a. Show a => a -> String
show Term
ty' String -> String -> String
forall a. [a] -> [a] -> [a]
++ " : " String -> String -> String
forall a. [a] -> [a] -> [a]
++ Term -> String
forall a. Show a => a -> String
show Term
typ)

         -- Elaborate the provider term to TT and check that the type matches
         (e :: Term
e, et :: Term
et) <- case ProvideWhat
what of
                      ProvTerm _ tm :: PTerm
tm    -> ElabInfo -> ElabMode -> PTerm -> Idris (Term, Term)
elabVal ElabInfo
info ElabMode
ERHS PTerm
tm
                      ProvPostulate tm :: PTerm
tm -> ElabInfo -> ElabMode -> PTerm -> Idris (Term, Term)
elabVal ElabInfo
info ElabMode
ERHS PTerm
tm
         Bool -> Idris () -> Idris ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
unless (Context -> Term -> Term -> Bool
isProviderOf Context
ctxt Term
ty' Term
et) (Idris () -> Idris ()) -> Idris () -> Idris ()
forall a b. (a -> b) -> a -> b
$
           String -> Idris ()
forall a. String -> Idris a
ifail (String -> Idris ()) -> String -> Idris ()
forall a b. (a -> b) -> a -> b
$ "Expected provider type " String -> String -> String
forall a. [a] -> [a] -> [a]
++ Term -> String
forall a. Show a => a -> String
show (Term -> Term
providerOf Term
ty') String -> String -> String
forall a. [a] -> [a] -> [a]
++
                   ", got " String -> String -> String
forall a. [a] -> [a] -> [a]
++ Term -> String
forall a. Show a => a -> String
show Term
et String -> String -> String
forall a. [a] -> [a] -> [a]
++ " instead."

         -- Execute the type provider and normalise the result
         -- use 'run__provider' to convert to a primitive IO action

         Term
rhs <- Term -> Idris Term
execute (Term -> [Term] -> Term
forall n. TT n -> [TT n] -> TT n
mkApp (NameType -> Name -> Term -> Term
forall n. NameType -> n -> TT n -> TT n
P NameType
Ref (String -> Name
sUN "run__provider") Term
forall n. TT n
Erased)
                                          [Term
forall n. TT n
Erased, Term
e])
         let rhs' :: Term
rhs' = Context -> Env -> Term -> Term
normalise Context
ctxt [] Term
rhs
         Int -> String -> Idris ()
logElab 3 (String -> Idris ()) -> String -> Idris ()
forall a b. (a -> b) -> a -> b
$ "Normalised " String -> String -> String
forall a. [a] -> [a] -> [a]
++ Name -> String
forall a. Show a => a -> String
show Name
n String -> String -> String
forall a. [a] -> [a] -> [a]
++ "'s RHS to " String -> String -> String
forall a. [a] -> [a] -> [a]
++ Term -> String
forall a. Show a => a -> String
show Term
rhs

         -- Extract the provided term or postulate from the type provider
         Provided Term
provided <- FC -> Term -> Idris (Provided Term)
getProvided FC
fc Term
rhs'

         case Provided Term
provided of
           Provide tm :: Term
tm
             | ProvTerm ty :: PTerm
ty _ <- ProvideWhat
what ->
               do -- Finally add a top-level definition of the provided term
                  ElabInfo
-> SyntaxInfo
-> Docstring (Either Err PTerm)
-> [(Name, Docstring (Either Err PTerm))]
-> FC
-> FnOpts
-> Name
-> FC
-> PTerm
-> Idris Term
elabType ElabInfo
info SyntaxInfo
syn Docstring (Either Err PTerm)
doc [] FC
fc [] Name
n FC
NoFC PTerm
ty
                  ElabInfo -> FC -> FnOpts -> Name -> [PClause] -> Idris ()
elabClauses ElabInfo
info FC
fc [] Name
n [FC
-> Name -> PTerm -> [PTerm] -> PTerm -> [PDecl' PTerm] -> PClause
forall t. FC -> Name -> t -> [t] -> t -> [PDecl' t] -> PClause' t
PClause FC
fc Name
n (FC -> PTerm -> [PArg] -> PTerm
PApp FC
fc (FC -> [FC] -> Name -> PTerm
PRef FC
fc [] Name
n) []) [] (IState -> Term -> PTerm
delab IState
i Term
tm) []]
                  Int -> String -> Idris ()
logElab 3 (String -> Idris ()) -> String -> Idris ()
forall a b. (a -> b) -> a -> b
$ "Elaborated provider " String -> String -> String
forall a. [a] -> [a] -> [a]
++ Name -> String
forall a. Show a => a -> String
show Name
n String -> String -> String
forall a. [a] -> [a] -> [a]
++ " as: " String -> String -> String
forall a. [a] -> [a] -> [a]
++ Term -> String
forall a. Show a => a -> String
show Term
tm
             | ProvPostulate _ <- ProvideWhat
what ->
               do -- Add the postulate
                  ElabInfo
-> SyntaxInfo
-> Docstring (Either Err PTerm)
-> FC
-> FC
-> FnOpts
-> Name
-> PTerm
-> Idris ()
elabPostulate ElabInfo
info SyntaxInfo
syn Docstring (Either Err PTerm)
doc FC
fc FC
nfc [] Name
n (IState -> Term -> PTerm
delab IState
i Term
tm)
                  Int -> String -> Idris ()
logElab 3 (String -> Idris ()) -> String -> Idris ()
forall a b. (a -> b) -> a -> b
$ "Elaborated provided postulate " String -> String -> String
forall a. [a] -> [a] -> [a]
++ Name -> String
forall a. Show a => a -> String
show Name
n
             | Bool
otherwise ->
               Err -> Idris ()
forall a. Err -> Idris a
ierror (Err -> Idris ()) -> (String -> Err) -> String -> Idris ()
forall k (cat :: k -> k -> *) (b :: k) (c :: k) (a :: k).
Category cat =>
cat b c -> cat a b -> cat a c
. String -> Err
forall t. String -> Err' t
Msg (String -> Idris ()) -> String -> Idris ()
forall a b. (a -> b) -> a -> b
$ "Attempted to provide a postulate where a term was expected."

    where isTType :: TT Name -> Bool
          isTType :: Term -> Bool
isTType (TType _) = Bool
True
          isTType _ = Bool
False

          -- Note: IO (Providers.Provider ty) is used instead of IO'
          -- (MkFFI C_FFI) (Providers.Provider ty) in hopes of better
          -- error messages with less normalisation
          providerOf :: Type -> Type
          providerOf :: Term -> Term
providerOf ty :: Term
ty = AppStatus Name -> Term -> Term -> Term
forall n. AppStatus n -> TT n -> TT n -> TT n
App AppStatus Name
forall n. AppStatus n
Complete (NameType -> Name -> Term -> Term
forall n. NameType -> n -> TT n -> TT n
P NameType
Ref (String -> Name
sUN "IO") Term
forall n. TT n
Erased) (Term -> Term) -> Term -> Term
forall a b. (a -> b) -> a -> b
$
                            AppStatus Name -> Term -> Term -> Term
forall n. AppStatus n -> TT n -> TT n -> TT n
App AppStatus Name
forall n. AppStatus n
Complete (NameType -> Name -> Term -> Term
forall n. NameType -> n -> TT n -> TT n
P NameType
Ref (Name -> [String] -> Name
sNS (String -> Name
sUN "Provider") ["Providers", "Prelude"]) Term
forall n. TT n
Erased)
                              Term
ty

          isProviderOf :: Context -> TT Name -> TT Name -> Bool
          isProviderOf :: Context -> Term -> Term -> Bool
isProviderOf ctxt :: Context
ctxt tp :: Term
tp prov :: Term
prov =
            case Context -> Env -> Term -> Term -> TC ()
converts Context
ctxt [] (Term -> Term
providerOf Term
tp) Term
prov of
              OK _ -> Bool
True
              _    -> Bool
False