[Git][ghc/ghc][master] base: Introduce Data.Enum.enumerate (CLC #306)

[Marge Bot (@marge-bot)]

Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC


Commits:
a963a1a5 by Marc Scholten at 2025-01-29T02:28:35-05:00
base: Introduce Data.Enum.enumerate (CLC #306)

https://github.com/haskell/core-libraries-committee/issues/306

- - - - -


6 changed files:

- libraries/base/changelog.md
- libraries/base/src/Data/Enum.hs
- testsuite/tests/interface-stability/base-exports.stdout
- testsuite/tests/interface-stability/base-exports.stdout-javascript-unknown-ghcjs
- testsuite/tests/interface-stability/base-exports.stdout-mingw32
- testsuite/tests/interface-stability/base-exports.stdout-ws-32


Changes:

=====================================
libraries/base/changelog.md
=====================================
@@ -9,6 +9,7 @@
   * `Data.List.NonEmpty.{init,last,tails1}` are now defined using only total functions (rather than partial ones). ([CLC proposal #293](https://github.com/haskell/core-libraries-committee/issues/293))
   * `Data.List.NonEmpty` functions now have the same laziness as their `Data.List` counterparts (i.e. make them more strict than they currently are) ([CLC proposal #107](https://github.com/haskell/core-libraries-committee/issues/107))
   * `instance Functor NonEmpty` is now specified using `map` (rather than duplicating code). ([CLC proposal #300](https://github.com/haskell/core-libraries-committee/issues/300))
+  * The `Data.Enum.enumerate` function was introduced ([CLC #306](https://github.com/haskell/core-libraries-committee/issues/306))
 
 ## 4.21.0.0 *TBA*
   * Change `SrcLoc` to be a strict and unboxed (finishing [CLC proposal #55](https://github.com/haskell/core-libraries-committee/issues/55))


=====================================
libraries/base/src/Data/Enum.hs
=====================================
@@ -21,6 +21,34 @@ module Data.Enum
     ( Enum(..)
     , {-# DEPRECATED "Bounded should be imported from Data.Bounded" #-}
       Bounded(..)
+    , enumerate
     ) where
 
 import GHC.Internal.Enum
+
+-- | Returns a list of all values of an enum type
+--
+-- 'enumerate' is often used to list all values of a custom enum data structure, such as a custom Color enum below:
+--
+-- @
+-- data Color = Yellow | Red | Blue
+--     deriving (Enum, Bounded, Show)
+--
+-- allColors :: [Color]
+-- allColors = enumerate
+-- -- Result: [Yellow, Red, Blue]
+-- @
+--
+-- Note that you need to derive the 'Bounded' type class as well, only 'Enum' is not enough.
+-- 'Enum' allows for sequential enumeration, while 'Bounded' provides the 'minBound' and 'maxBound' values.
+--
+-- 'enumerate' is commonly used together with the TypeApplications syntax. Here is an example of using 'enumerate' to retrieve all values of the 'Ordering' type:
+--
+-- >> enumerate @Ordering
+-- [LT, EQ, GT]
+--
+-- The '@' symbol here is provided by the TypeApplications language extension.
+--
+-- @since base-4.22.0.0
+enumerate :: (Enum a, Bounded a) => [a]
+enumerate = [minBound .. maxBound]
\ No newline at end of file


=====================================
testsuite/tests/interface-stability/base-exports.stdout
=====================================
@@ -979,6 +979,7 @@ module Data.Enum where
     enumFromTo :: a -> a -> [a]
     enumFromThenTo :: a -> a -> a -> [a]
     {-# MINIMAL toEnum, fromEnum #-}
+  enumerate :: forall a. (Enum a, Bounded a) => [a]
 
 module Data.Eq where
   -- Safety: Safe


=====================================
testsuite/tests/interface-stability/base-exports.stdout-javascript-unknown-ghcjs
=====================================
@@ -979,6 +979,7 @@ module Data.Enum where
     enumFromTo :: a -> a -> [a]
     enumFromThenTo :: a -> a -> a -> [a]
     {-# MINIMAL toEnum, fromEnum #-}
+  enumerate :: forall a. (Enum a, Bounded a) => [a]
 
 module Data.Eq where
   -- Safety: Safe


=====================================
testsuite/tests/interface-stability/base-exports.stdout-mingw32
=====================================
@@ -979,6 +979,7 @@ module Data.Enum where
     enumFromTo :: a -> a -> [a]
     enumFromThenTo :: a -> a -> a -> [a]
     {-# MINIMAL toEnum, fromEnum #-}
+  enumerate :: forall a. (Enum a, Bounded a) => [a]
 
 module Data.Eq where
   -- Safety: Safe


=====================================
testsuite/tests/interface-stability/base-exports.stdout-ws-32
=====================================
@@ -979,6 +979,7 @@ module Data.Enum where
     enumFromTo :: a -> a -> [a]
     enumFromThenTo :: a -> a -> a -> [a]
     {-# MINIMAL toEnum, fromEnum #-}
+  enumerate :: forall a. (Enum a, Bounded a) => [a]
 
 module Data.Eq where
   -- Safety: Safe



View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/a963a1a5d38cd6fbb722f3d25c31744238d71b65

-- 
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/a963a1a5d38cd6fbb722f3d25c31744238d71b65
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