ref: 5b6168bbba78656837ecb73c48ba207cd514d7ea
parent: c101325aaf8ed0ec3c8c4ff4b7d425bba799825a
author: konsumlamm <konsumlamm@gmail.com>
date: Wed Jan 8 10:57:27 EST 2025
Define helpers for `Enum` instances of numeric types Add `Enum (Ratio a)` instance
--- a/lib/Data/Enum.hs
+++ b/lib/Data/Enum.hs
@@ -40,6 +40,25 @@
i_n1 = fromEnum n1
i_n2 = fromEnum n2
+numericEnumFrom :: (Num a) => a -> [a]
+numericEnumFrom n = n : numericEnumFrom (n + 1)
+
+numericEnumFromThen :: (Num a) => a -> a -> [a]
+numericEnumFromThen n m = from n
+ where
+ d = m - n
+ from i = i : from (i + d)
+
+numericEnumFromTo :: (Num a, Ord a) => a -> a -> [a]
+numericEnumFromTo l h = takeWhile (<= h) (numericEnumFrom l)
+
+numericEnumFromThenTo :: (Num a, Ord a) => a -> a -> a -> [a]
+numericEnumFromThenTo l m h =
+ if m > l then
+ takeWhile (<= h) (numericEnumFromThen l m)
+ else
+ takeWhile (>= h) (numericEnumFromThen l m)
+
-- This instance is difficult to put in Data.Int,
-- so it gets to live here.
instance Enum Int where
@@ -47,16 +66,10 @@
pred x = x - 1
toEnum x = x
fromEnum x = x
- enumFrom n = n : enumFrom (n+1)
- enumFromThen n m = from n
- where d = m - n
- from i = i : from (i+d)
- enumFromTo l h = takeWhile (<= h) (enumFrom l)
- enumFromThenTo l m h =
- if m > l then
- takeWhile (<= h) (enumFromThen l m)
- else
- takeWhile (>= h) (enumFromThen l m)
+ enumFrom = numericEnumFrom
+ enumFromThen = numericEnumFromThen
+ enumFromTo = numericEnumFromTo
+ enumFromThenTo = numericEnumFromThenTo
-- Likewise for Bool
instance Enum Bool where
--- a/lib/Data/Int/Instances.hs
+++ b/lib/Data/Int/Instances.hs
@@ -72,16 +72,10 @@
pred x = x - 1
toEnum = i8
fromEnum = unI8
- enumFrom n = n : enumFrom (n+1)
- enumFromThen n m = from n
- where d = m - n
- from i = i : from (i+d)
- enumFromTo l h = takeWhile (<= h) (enumFrom l)
- enumFromThenTo l m h =
- if m > l then
- takeWhile (<= h) (enumFromThen l m)
- else
- takeWhile (>= h) (enumFromThen l m)
+ enumFrom = numericEnumFrom
+ enumFromThen = numericEnumFromThen
+ enumFromTo = numericEnumFromTo
+ enumFromThenTo = numericEnumFromThenTo
instance Eq Int8 where
(==) = cmp8 primIntEQ
@@ -162,16 +156,10 @@
pred x = x - 1
toEnum = i16
fromEnum = unI16
- enumFrom n = n : enumFrom (n+1)
- enumFromThen n m = from n
- where d = m - n
- from i = i : from (i+d)
- enumFromTo l h = takeWhile (<= h) (enumFrom l)
- enumFromThenTo l m h =
- if m > l then
- takeWhile (<= h) (enumFromThen l m)
- else
- takeWhile (>= h) (enumFromThen l m)
+ enumFrom = numericEnumFrom
+ enumFromThen = numericEnumFromThen
+ enumFromTo = numericEnumFromTo
+ enumFromThenTo = numericEnumFromThenTo
instance Eq Int16 where
(==) = cmp16 primIntEQ
@@ -252,16 +240,10 @@
pred x = x - 1
toEnum = i32
fromEnum = unI32
- enumFrom n = n : enumFrom (n+1)
- enumFromThen n m = from n
- where d = m - n
- from i = i : from (i+d)
- enumFromTo l h = takeWhile (<= h) (enumFrom l)
- enumFromThenTo l m h =
- if m > l then
- takeWhile (<= h) (enumFromThen l m)
- else
- takeWhile (>= h) (enumFromThen l m)
+ enumFrom = numericEnumFrom
+ enumFromThen = numericEnumFromThen
+ enumFromTo = numericEnumFromTo
+ enumFromThenTo = numericEnumFromThenTo
instance Eq Int32 where
(==) = cmp32 primIntEQ
@@ -340,16 +322,10 @@
pred x = x - 1
toEnum = i64
fromEnum = unI64
- enumFrom n = n : enumFrom (n+1)
- enumFromThen n m = from n
- where d = m - n
- from i = i : from (i+d)
- enumFromTo l h = takeWhile (<= h) (enumFrom l)
- enumFromThenTo l m h =
- if m > l then
- takeWhile (<= h) (enumFromThen l m)
- else
- takeWhile (>= h) (enumFromThen l m)
+ enumFrom = numericEnumFrom
+ enumFromThen = numericEnumFromThen
+ enumFromTo = numericEnumFromTo
+ enumFromThenTo = numericEnumFromThenTo
instance Eq Int64 where
(==) = cmp64 primIntEQ
--- a/lib/Data/Integer.hs
+++ b/lib/Data/Integer.hs
@@ -93,16 +93,10 @@
pred x = x - 1
toEnum x = _intToInteger x
fromEnum x = _integerToInt x
- enumFrom n = n : enumFrom (n+1)
- enumFromThen n m = from n
- where d = m - n
- from i = i : from (i+d)
- enumFromTo l h = takeWhile (<= h) (enumFrom l)
- enumFromThenTo l m h =
- if m > l then
- takeWhile (<= h) (enumFromThen l m)
- else
- takeWhile (>= h) (enumFromThen l m)
+ enumFrom = numericEnumFrom
+ enumFromThen = numericEnumFromThen
+ enumFromTo = numericEnumFromTo
+ enumFromThenTo = numericEnumFromThenTo
------------------------------------------------
--- a/lib/Data/Ratio.hs
+++ b/lib/Data/Ratio.hs
@@ -9,6 +9,7 @@
) where
import Prelude() -- do not import Prelude
import Data.Bool
+import Data.Enum
import Data.Eq
import Data.Fractional
import Data.Function
@@ -42,6 +43,16 @@
-- NOTE. Experimentally, we extend this with:
-- x/0 == 1/0 when x > 0
-- x/0 == -1/0 when x < 0
+
+instance (Integral a) => Enum (Ratio a) where
+ succ x = x + 1
+ pred x = x - 1
+ toEnum = fromIntegral
+ fromEnum = fromInteger . truncate
+ enumFrom = numericEnumFrom
+ enumFromThen = numericEnumFromThen
+ enumFromTo = numericEnumFromTo
+ enumFromThenTo = numericEnumFromThenTo
instance forall a . Eq a => Eq (Ratio a) where
(x :% y) == (x' :% y') = x == x' && y == y'
--- a/lib/Data/Word.hs
+++ b/lib/Data/Word.hs
@@ -57,16 +57,10 @@
pred x = x - 1
toEnum = primIntToWord
fromEnum = primWordToInt
- enumFrom n = n : enumFrom (n+1)
- enumFromThen n m = from n
- where d = m - n
- from i = i : from (i+d)
- enumFromTo l h = takeWhile (<= h) (enumFrom l)
- enumFromThenTo l m h =
- if m > l then
- takeWhile (<= h) (enumFromThen l m)
- else
- takeWhile (>= h) (enumFromThen l m)
+ enumFrom = numericEnumFrom
+ enumFromThen = numericEnumFromThen
+ enumFromTo = numericEnumFromTo
+ enumFromThenTo = numericEnumFromThenTo
--------------------------------
@@ -154,16 +148,10 @@
pred x = x - 1
toEnum = w8 . primIntToWord
fromEnum = primWordToInt . unW8
- enumFrom n = n : enumFrom (n+1)
- enumFromThen n m = from n
- where d = m - n
- from i = i : from (i+d)
- enumFromTo l h = takeWhile (<= h) (enumFrom l)
- enumFromThenTo l m h =
- if m > l then
- takeWhile (<= h) (enumFromThen l m)
- else
- takeWhile (>= h) (enumFromThen l m)
+ enumFrom = numericEnumFrom
+ enumFromThen = numericEnumFromThen
+ enumFromTo = numericEnumFromTo
+ enumFromThenTo = numericEnumFromThenTo
instance Eq Word8 where
(==) = cmp8 primWordEQ
@@ -245,17 +233,10 @@
succ x = x + 1
pred x = x - 1
toEnum = w16 . primIntToWord
- fromEnum = primWordToInt . unW16
- enumFrom n = n : enumFrom (n+1)
- enumFromThen n m = from n
- where d = m - n
- from i = i : from (i+d)
- enumFromTo l h = takeWhile (<= h) (enumFrom l)
- enumFromThenTo l m h =
- if m > l then
- takeWhile (<= h) (enumFromThen l m)
- else
- takeWhile (>= h) (enumFromThen l m)
+ enumFrom = numericEnumFrom
+ enumFromThen = numericEnumFromThen
+ enumFromTo = numericEnumFromTo
+ enumFromThenTo = numericEnumFromThenTo
instance Eq Word16 where
(==) = cmp16 primWordEQ
@@ -338,16 +319,10 @@
pred x = x - 1
toEnum = w32 . primIntToWord
fromEnum = primWordToInt . unW32
- enumFrom n = n : enumFrom (n+1)
- enumFromThen n m = from n
- where d = m - n
- from i = i : from (i+d)
- enumFromTo l h = takeWhile (<= h) (enumFrom l)
- enumFromThenTo l m h =
- if m > l then
- takeWhile (<= h) (enumFromThen l m)
- else
- takeWhile (>= h) (enumFromThen l m)
+ enumFrom = numericEnumFrom
+ enumFromThen = numericEnumFromThen
+ enumFromTo = numericEnumFromTo
+ enumFromThenTo = numericEnumFromThenTo
instance Eq Word32 where
(==) = cmp32 primWordEQ
@@ -430,16 +405,10 @@
pred x = x - 1
toEnum = w64 . primIntToWord
fromEnum = primWordToInt . unW64
- enumFrom n = n : enumFrom (n+1)
- enumFromThen n m = from n
- where d = m - n
- from i = i : from (i+d)
- enumFromTo l h = takeWhile (<= h) (enumFrom l)
- enumFromThenTo l m h =
- if m > l then
- takeWhile (<= h) (enumFromThen l m)
- else
- takeWhile (>= h) (enumFromThen l m)
+ enumFrom = numericEnumFrom
+ enumFromThen = numericEnumFromThen
+ enumFromTo = numericEnumFromTo
+ enumFromThenTo = numericEnumFromThenTo
instance Eq Word64 where
(==) = cmp64 primWordEQ