Hash.hs

{-# LANGUAGE OverloadedStrings #-}

-- | This module contains the implementation of the @dhall hash@ subcommand

module Dhall.Hash
    ( -- * Hash
      hash
    ) where

import Dhall.Parser (exprFromText)
import Dhall.Import (hashExpressionToCode)

import qualified Control.Monad.Trans.State.Strict as State
import qualified Control.Exception
import qualified Dhall.Core
import qualified Dhall.Import
import qualified Dhall.TypeCheck
import qualified Data.Text.IO

-- | Implementation of the @dhall hash@ subcommand
hash :: IO ()
hash = do
    inText <- Data.Text.IO.getContents

    parsedExpression <- case exprFromText "(stdin)" inText of
        Left  exception        -> Control.Exception.throwIO exception
        Right parsedExpression -> return parsedExpression

    let status = Dhall.Import.emptyStatus "."

    resolvedExpression <- State.evalStateT (Dhall.Import.loadWith parsedExpression) status

    case Dhall.TypeCheck.typeOf resolvedExpression of
        Left  exception -> Control.Exception.throwIO exception
        Right _         -> return ()

    let normalizedExpression =
            Dhall.Core.alphaNormalize (Dhall.Core.normalize resolvedExpression)

    Data.Text.IO.putStrLn (hashExpressionToCode normalizedExpression)