{-# LANGUAGE CPP #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE ConstraintKinds #-}
{-# LANGUAGE Rank2Types #-}
{-# LANGUAGE PatternSynonyms #-}
{-# LANGUAGE ViewPatterns #-}
--------------------------------------------------------------------------------
-- |
-- Module      :  Numeric.Lens
-- Copyright   :  (C) 2012-16 Edward Kmett
-- License     :  BSD-style (see the file LICENSE)
-- Maintainer  :  Edward Kmett <ekmett@gmail.com>
-- Stability   :  provisional
-- Portability :  portable
-------------------------------------------------------------------------------
module Numeric.Lens
  ( base
  , integral
    -- * Predefined bases
  , binary
  , octal
  , decimal
  , hex
    -- * Arithmetic lenses
  , adding
  , subtracting
  , multiplying
  , dividing
  , exponentiating
  , negated
  , pattern Integral
  ) where

import Control.Lens
import Data.CallStack
import Data.Char (chr, ord, isAsciiLower, isAsciiUpper, isDigit)
import Data.Maybe (fromMaybe)
import Numeric (readInt, showIntAtBase)

-- $setup
-- >>> :set -XNoOverloadedStrings
-- >>> import Control.Lens
-- >>> import Data.Monoid (Sum(..))

-- | This t'Prism' can be used to model the fact that every t'Integral'
-- type is a subset of 'Integer'.
--
-- Embedding through the t'Prism' only succeeds if the 'Integer' would pass
-- through unmodified when re-extracted.
integral :: (Integral a, Integral b) => Prism Integer Integer a b
integral :: forall a b. (Integral a, Integral b) => Prism Integer Integer a b
integral = (b -> Integer)
-> (Integer -> Either Integer a) -> Prism Integer Integer a b
forall b t s a. (b -> t) -> (s -> Either t a) -> Prism s t a b
prism b -> Integer
forall a. Integral a => a -> Integer
toInteger ((Integer -> Either Integer a) -> Prism Integer Integer a b)
-> (Integer -> Either Integer a) -> Prism Integer Integer a b
forall a b. (a -> b) -> a -> b
$ \ Integer
i -> let a :: a
a = Integer -> a
forall a. Num a => Integer -> a
fromInteger Integer
i in
  if a -> Integer
forall a. Integral a => a -> Integer
toInteger a
a Integer -> Integer -> Bool
forall a. Eq a => a -> a -> Bool
== Integer
i
  then a -> Either Integer a
forall a b. b -> Either a b
Right a
a
  else Integer -> Either Integer a
forall a b. a -> Either a b
Left Integer
i

pattern Integral :: Integral a => a -> Integer
pattern $mIntegral :: forall {r} {a}.
Integral a =>
Integer -> (a -> r) -> ((# #) -> r) -> r
$bIntegral :: forall a. Integral a => a -> Integer
Integral a <- (preview integral -> Just a) where
  Integral a
a = AReview Integer a -> a -> Integer
forall b (m :: * -> *) t. MonadReader b m => AReview t b -> m t
review AReview Integer a
forall a b. (Integral a, Integral b) => Prism Integer Integer a b
Prism Integer Integer a a
integral a
a

-- | A prism that shows and reads integers in base-2 through base-36
--
-- Note: This is an improper prism, since leading 0s are stripped when reading.
--
-- >>> "100" ^? base 16
-- Just 256
--
-- >>> 1767707668033969 ^. re (base 36)
-- "helloworld"
base :: (HasCallStack, Integral a) => Int -> Prism' String a
base :: forall a. (HasCallStack, Integral a) => Int -> Prism' String a
base Int
b
  | Int
b Int -> Int -> Bool
forall a. Ord a => a -> a -> Bool
< Int
2 Bool -> Bool -> Bool
|| Int
b Int -> Int -> Bool
forall a. Ord a => a -> a -> Bool
> Int
36 = String -> p a (f a) -> p String (f String)
forall a. HasCallStack => String -> a
error (String
"base: Invalid base " String -> String -> String
forall a. [a] -> [a] -> [a]
++ Int -> String
forall a. Show a => a -> String
show Int
b)
  | Bool
otherwise       = (a -> String)
-> (String -> Either String a) -> Prism String String a a
forall b t s a. (b -> t) -> (s -> Either t a) -> Prism s t a b
prism a -> String
forall {a}. Integral a => a -> String
intShow String -> Either String a
forall {b}. Real b => String -> Either String b
intRead
  where
    intShow :: a -> String
intShow a
n = (Integer -> String -> String) -> Integer -> String -> String
forall a.
Real a =>
(a -> String -> String) -> a -> String -> String
showSigned' (Integer -> (Int -> Char) -> Integer -> String -> String
forall a. Integral a => a -> (Int -> Char) -> a -> String -> String
showIntAtBase (Int -> Integer
forall a. Integral a => a -> Integer
toInteger Int
b) HasCallStack => Int -> Char
Int -> Char
intToDigit') (a -> Integer
forall a. Integral a => a -> Integer
toInteger a
n) String
""

    intRead :: String -> Either String b
intRead String
s =
      case ReadS b -> ReadS b
forall a. Real a => ReadS a -> ReadS a
readSigned' (b -> (Char -> Bool) -> (Char -> Int) -> ReadS b
forall a. Num a => a -> (Char -> Bool) -> (Char -> Int) -> ReadS a
readInt (Int -> b
forall a b. (Integral a, Num b) => a -> b
fromIntegral Int
b) (Int -> Char -> Bool
isDigit' Int
b) HasCallStack => Char -> Int
Char -> Int
digitToInt') String
s of
        [(b
n,String
"")] -> b -> Either String b
forall a b. b -> Either a b
Right b
n
        [(b, String)]
_ -> String -> Either String b
forall a b. a -> Either a b
Left String
s
{-# INLINE base #-}

-- | Like 'Data.Char.intToDigit', but handles up to base-36
intToDigit' :: HasCallStack => Int -> Char
intToDigit' :: HasCallStack => Int -> Char
intToDigit' Int
i
  | Int
i Int -> Int -> Bool
forall a. Ord a => a -> a -> Bool
>= Int
0  Bool -> Bool -> Bool
&& Int
i Int -> Int -> Bool
forall a. Ord a => a -> a -> Bool
< Int
10 = Int -> Char
chr (Char -> Int
ord Char
'0' Int -> Int -> Int
forall a. Num a => a -> a -> a
+ Int
i)
  | Int
i Int -> Int -> Bool
forall a. Ord a => a -> a -> Bool
>= Int
10 Bool -> Bool -> Bool
&& Int
i Int -> Int -> Bool
forall a. Ord a => a -> a -> Bool
< Int
36 = Int -> Char
chr (Char -> Int
ord Char
'a' Int -> Int -> Int
forall a. Num a => a -> a -> a
+ Int
i Int -> Int -> Int
forall a. Num a => a -> a -> a
- Int
10)
  | Bool
otherwise = String -> Char
forall a. HasCallStack => String -> a
error (String
"intToDigit': Invalid int " String -> String -> String
forall a. [a] -> [a] -> [a]
++ Int -> String
forall a. Show a => a -> String
show Int
i)

-- | Like 'Data.Char.digitToInt', but handles up to base-36
digitToInt' :: HasCallStack => Char -> Int
digitToInt' :: HasCallStack => Char -> Int
digitToInt' Char
c = Int -> Maybe Int -> Int
forall a. a -> Maybe a -> a
fromMaybe (String -> Int
forall a. HasCallStack => String -> a
error (String
"digitToInt': Invalid digit " String -> String -> String
forall a. [a] -> [a] -> [a]
++ Char -> String
forall a. Show a => a -> String
show Char
c))
                          (Char -> Maybe Int
digitToIntMay Char
c)

-- | A safe variant of 'digitToInt''
digitToIntMay :: Char -> Maybe Int
digitToIntMay :: Char -> Maybe Int
digitToIntMay Char
c
  | Char -> Bool
isDigit Char
c      = Int -> Maybe Int
forall a. a -> Maybe a
Just (Char -> Int
ord Char
c Int -> Int -> Int
forall a. Num a => a -> a -> a
- Char -> Int
ord Char
'0')
  | Char -> Bool
isAsciiLower Char
c = Int -> Maybe Int
forall a. a -> Maybe a
Just (Char -> Int
ord Char
c Int -> Int -> Int
forall a. Num a => a -> a -> a
- Char -> Int
ord Char
'a' Int -> Int -> Int
forall a. Num a => a -> a -> a
+ Int
10)
  | Char -> Bool
isAsciiUpper Char
c = Int -> Maybe Int
forall a. a -> Maybe a
Just (Char -> Int
ord Char
c Int -> Int -> Int
forall a. Num a => a -> a -> a
- Char -> Int
ord Char
'A' Int -> Int -> Int
forall a. Num a => a -> a -> a
+ Int
10)
  | Bool
otherwise = Maybe Int
forall a. Maybe a
Nothing

-- | Select digits that fall into the given base
isDigit' :: Int -> Char -> Bool
isDigit' :: Int -> Char -> Bool
isDigit' Int
b Char
c = case Char -> Maybe Int
digitToIntMay Char
c of
  Just Int
i -> Int
i Int -> Int -> Bool
forall a. Ord a => a -> a -> Bool
< Int
b
  Maybe Int
_ -> Bool
False

-- | A simpler variant of 'Numeric.showSigned' that only prepends a dash and
-- doesn't know about parentheses
showSigned' :: Real a => (a -> ShowS) -> a -> ShowS
showSigned' :: forall a.
Real a =>
(a -> String -> String) -> a -> String -> String
showSigned' a -> String -> String
f a
n
  | a
n a -> a -> Bool
forall a. Ord a => a -> a -> Bool
< a
0     = Char -> String -> String
showChar Char
'-' (String -> String) -> (String -> String) -> String -> String
forall b c a. (b -> c) -> (a -> b) -> a -> c
. a -> String -> String
f (a -> a
forall a. Num a => a -> a
negate a
n)
  | Bool
otherwise = a -> String -> String
f a
n

-- | A simpler variant of 'Numeric.readSigned' that supports any base, only
-- recognizes an initial dash and doesn't know about parentheses
readSigned' :: Real a => ReadS a -> ReadS a
readSigned' :: forall a. Real a => ReadS a -> ReadS a
readSigned' ReadS a
f (Char
'-':String
xs) = ReadS a
f String
xs [(a, String)] -> ((a, String) -> (a, String)) -> [(a, String)]
forall (f :: * -> *) a b. Functor f => f a -> (a -> b) -> f b
<&> (a -> Identity a) -> (a, String) -> Identity (a, String)
forall s t a b. Field1 s t a b => Lens s t a b
Lens (a, String) (a, String) a a
_1 ((a -> Identity a) -> (a, String) -> Identity (a, String))
-> (a -> a) -> (a, String) -> (a, String)
forall s t a b. ASetter s t a b -> (a -> b) -> s -> t
%~ a -> a
forall a. Num a => a -> a
negate
readSigned' ReadS a
f String
xs       = ReadS a
f String
xs

-- | @'binary' = 'base' 2@
binary :: Integral a => Prism' String a
binary :: forall a. Integral a => Prism' String a
binary = Int -> Prism' String a
forall a. (HasCallStack, Integral a) => Int -> Prism' String a
base Int
2

-- | @'octal' = 'base' 8@
octal :: Integral a => Prism' String a
octal :: forall a. Integral a => Prism' String a
octal = Int -> Prism' String a
forall a. (HasCallStack, Integral a) => Int -> Prism' String a
base Int
8

-- | @'decimal' = 'base' 10@
decimal :: Integral a => Prism' String a
decimal :: forall a. Integral a => Prism' String a
decimal = Int -> Prism' String a
forall a. (HasCallStack, Integral a) => Int -> Prism' String a
base Int
10

-- | @'hex' = 'base' 16@
hex :: Integral a => Prism' String a
hex :: forall a. Integral a => Prism' String a
hex = Int -> Prism' String a
forall a. (HasCallStack, Integral a) => Int -> Prism' String a
base Int
16

-- | @'adding' n = 'iso' (+n) (subtract n)@
--
-- >>> [1..3]^..traverse.adding 1000
-- [1001,1002,1003]
adding :: Num a => a -> Iso' a a
adding :: forall a. Num a => a -> Iso' a a
adding a
n = (a -> a) -> (a -> a) -> Iso a a a a
forall s a b t. (s -> a) -> (b -> t) -> Iso s t a b
iso (a -> a -> a
forall a. Num a => a -> a -> a
+a
n) (a -> a -> a
forall a. Num a => a -> a -> a
subtract a
n)

-- | @
-- 'subtracting' n = 'iso' (subtract n) ((+n)
-- 'subtracting' n = 'from' ('adding' n)
-- @
subtracting :: Num a => a -> Iso' a a
subtracting :: forall a. Num a => a -> Iso' a a
subtracting a
n = (a -> a) -> (a -> a) -> Iso a a a a
forall s a b t. (s -> a) -> (b -> t) -> Iso s t a b
iso (a -> a -> a
forall a. Num a => a -> a -> a
subtract a
n) (a -> a -> a
forall a. Num a => a -> a -> a
+a
n)

-- | @'multiplying' n = iso (*n) (/n)@
--
-- Note: This errors for n = 0
--
-- >>> 5 & multiplying 1000 +~ 3
-- 5.003
--
-- >>> let fahrenheit = multiplying (9/5).adding 32 in 230^.from fahrenheit
-- 110.0
multiplying :: (Fractional a, Eq a) => a -> Iso' a a
multiplying :: forall a. (Fractional a, Eq a) => a -> Iso' a a
multiplying a
0 = String -> p a (f a) -> p a (f a)
forall a. HasCallStack => String -> a
error String
"Numeric.Lens.multiplying: factor 0"
multiplying a
n = (a -> a) -> (a -> a) -> Iso a a a a
forall s a b t. (s -> a) -> (b -> t) -> Iso s t a b
iso (a -> a -> a
forall a. Num a => a -> a -> a
*a
n) (a -> a -> a
forall a. Fractional a => a -> a -> a
/a
n)

-- | @
-- 'dividing' n = 'iso' (/n) (*n)
-- 'dividing' n = 'from' ('multiplying' n)@
--
-- Note: This errors for n = 0
dividing :: (Fractional a, Eq a) => a -> Iso' a a
dividing :: forall a. (Fractional a, Eq a) => a -> Iso' a a
dividing a
0 = String -> p a (f a) -> p a (f a)
forall a. HasCallStack => String -> a
error String
"Numeric.Lens.dividing: divisor 0"
dividing a
n = (a -> a) -> (a -> a) -> Iso a a a a
forall s a b t. (s -> a) -> (b -> t) -> Iso s t a b
iso (a -> a -> a
forall a. Fractional a => a -> a -> a
/a
n) (a -> a -> a
forall a. Num a => a -> a -> a
*a
n)

-- | @'exponentiating' n = 'iso' (**n) (**recip n)@
--
-- Note: This errors for n = 0
--
-- >>> au (_Wrapping Sum . from (exponentiating 2)) (foldMapOf each) (3,4) == 5
-- True
exponentiating :: (Floating a, Eq a) => a -> Iso' a a
exponentiating :: forall a. (Floating a, Eq a) => a -> Iso' a a
exponentiating a
0 = String -> p a (f a) -> p a (f a)
forall a. HasCallStack => String -> a
error String
"Numeric.Lens.exponentiating: exponent 0"
exponentiating a
n = (a -> a) -> (a -> a) -> Iso a a a a
forall s a b t. (s -> a) -> (b -> t) -> Iso s t a b
iso (a -> a -> a
forall a. Floating a => a -> a -> a
**a
n) (a -> a -> a
forall a. Floating a => a -> a -> a
**a -> a
forall a. Fractional a => a -> a
recip a
n)


-- | @'negated' = 'iso' 'negate' 'negate'@
--
-- >>> au (_Wrapping Sum . negated) (foldMapOf each) (3,4) == 7
-- True
--
-- >>> au (_Wrapping Sum) (foldMapOf (each.negated)) (3,4) == -7
-- True
negated :: Num a => Iso' a a
negated :: forall a. Num a => Iso' a a
negated = (a -> a) -> (a -> a) -> Iso a a a a
forall s a b t. (s -> a) -> (b -> t) -> Iso s t a b
iso a -> a
forall a. Num a => a -> a
negate a -> a
forall a. Num a => a -> a
negate