morley-prelude-0.5.1: src/Unsafe.hs

-- SPDX-FileCopyrightText: 2021 Oxhead Alpha
-- SPDX-License-Identifier: LicenseRef-MIT-OA

{-# LANGUAGE NoImplicitPrelude #-}

-- | Unsafe utilities.
--
-- This module should be imported qualified.
module Unsafe
  ( module Universum.Unsafe

  -- * Unsafe converters between @Integral@ types checking for overflow/underflow
  , Unsafe.fromIntegral
  , Unsafe.fromInteger

  -- * Unsafe converters from @Either@ for making unsafe counter-parts of safe functions
  , unsafe
  , unsafeM
  ) where

import Fmt (Buildable, pretty)
import Morley.Prelude.FromIntegral (fromIntegralNoOverflow)
import Universum
import Universum.Unsafe

-- | Unsafe converter between 'Integral' types
-- checking for overflow/underflow. Return
-- @value@ if conversion does not produce
-- overflow/underflow and raise an exception
-- with corresponding error message otherwise.
--
-- It is needed to replace 'Universum.Base.fromIntegral'
-- which misses most of the overflow/underflow checks.
--
-- Note the function is strict in its argument.
fromIntegral :: (HasCallStack, Integral a, Integral b) => a -> b
fromIntegral = either (error . fromString . displayException) id . fromIntegralNoOverflow

-- | Unsafe converter between 'Integer' and 'Integral'
-- types checking for overflow/underflow. Return @value@
-- if conversion does not produce overflow/underflow and
-- raise an exception with corresponding error message
-- otherwise.
--
-- Note the function is strict in its argument.
fromInteger :: (HasCallStack, Integral a) => Integer -> a
fromInteger = Unsafe.fromIntegral

-- | Unsafe converter from 'Either', which uses buildable
-- 'Left' to throw an exception with 'error'.
--
-- It is primarily needed for making unsafe counter-parts
-- of safe functions. In particular, for replacing
-- @unsafeFName x = either (error . pretty) id@
-- constructors and converters, which produce many similar
-- functions at the call site, with @unsafe . fName $ x@.
unsafe :: (HasCallStack, Buildable a) => Either a b -> b
unsafe = either (error . pretty) id
{-# INLINE unsafe #-}

-- | Similar to 'unsafe' converter, but with the use of
-- monadic 'fail' and returning the result wrapped in a monad.
unsafeM :: (MonadFail m, Buildable a) => Either a b -> m b
unsafeM = either (fail . pretty) pure
{-# INLINE unsafeM #-}