{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE Strict #-}

-- |
--
-- This module implements a transformation from source to core
-- Futhark.
--
-- The source and core language is similar in spirit, but the core
-- language is much more regular (and mostly much simpler) in order to
-- make it easier to write program transformations.
--
-- * "Language.Futhark.Syntax" contains the source language definition.
--
-- * "Futhark.IR.Syntax" contains the core IR definition.
--
-- Specifically, internalisation generates the SOACS dialect of the
-- core IR ("Futhark.IR.SOACS").  This is then initially used by the
-- compiler middle-end.  The main differences between the source and
-- core IR are as follows:
--
-- * The core IR has no modules.  These are removed in
--   "Futhark.Internalise.Defunctorise".
--
-- * The core IR is monomorphic.  Polymorphic functions are monomorphised in
--   "Futhark.Internalise.Monomorphise"
--
-- * The core IR is first-order. "Futhark.Internalise.Defunctionalise"
--   removes higher-order functions.
--
-- * The core IR is in [ANF](https://en.wikipedia.org/wiki/A-normal_form).
--
-- * The core IR does not have arrays of tuples (or tuples or records
--   at all, really).  Arrays of tuples are turned into multiple
--   arrays.  For example, a source language transposition of an array
--   of pairs becomes a core IR that contains two transpositions of
--   two distinct arrays.  The guts of this transformation is in
--   "Futhark.Internalise.Exps".
--
-- * For the above reason, SOACs also accept multiple input arrays.
--   The available primitive operations are also somewhat different
--   than in the source language.  See 'Futhark.IR.SOACS.SOAC.SOAC'.
module Futhark.Internalise (internaliseProg) where

import qualified Data.Text as T
import Futhark.Compiler.Config
import Futhark.IR.SOACS as I hiding (stmPat)
import Futhark.Internalise.Defunctionalise as Defunctionalise
import Futhark.Internalise.Defunctorise as Defunctorise
import qualified Futhark.Internalise.Exps as Exps
import Futhark.Internalise.LiftLambdas as LiftLambdas
import Futhark.Internalise.Monad as I
import Futhark.Internalise.Monomorphise as Monomorphise
import Futhark.Util.Log
import Language.Futhark.Semantic (Imports)

-- | Convert a program in source Futhark to a program in the Futhark
-- core language.
internaliseProg ::
  (MonadFreshNames m, MonadLogger m) =>
  FutharkConfig ->
  Imports ->
  m (I.Prog SOACS)
internaliseProg config prog = do
  maybeLog "Defunctorising"
  prog_decs <- Defunctorise.transformProg prog
  maybeLog "Monomorphising"
  prog_decs' <- Monomorphise.transformProg prog_decs
  maybeLog "Lifting lambdas"
  prog_decs'' <- LiftLambdas.transformProg prog_decs'
  maybeLog "Defunctionalising"
  prog_decs''' <- Defunctionalise.transformProg prog_decs''
  maybeLog "Converting to core IR"
  Exps.transformProg (futharkSafe config) prog_decs'''
  where
    verbose = fst (futharkVerbose config) > NotVerbose
    maybeLog s
      | verbose = logMsg (s :: T.Text)
      | otherwise = pure ()