define upFromIncluding

fix #30

src/Data/Enum.purs

@@ -5,6 +5,7 @@ module Data.Enum
   , enumFromTo
   , enumFromThenTo
   , upFrom
+  , upFromIncluding
   , downFrom
   , Cardinality(..)
   , class BoundedEnum, cardinality, toEnum, fromEnum, toEnumWithDefaults
@@ -21,6 +22,7 @@ import Data.Char (fromCharCode, toCharCode)
 import Data.Either (Either(..))
 import Data.Maybe (Maybe(..), maybe, fromJust)
 import Data.Newtype (class Newtype, unwrap)
+import Data.NonEmpty (NonEmpty, (:|))
 import Data.Tuple (Tuple(..))
 import Data.Unfoldable (class Unfoldable, unfoldr)
 
@@ -131,9 +133,16 @@ intStepFromTo step from to =
 diag :: forall a. a -> Tuple a a
 diag a = Tuple a a
 
+-- | Results in all successors from given Enum in some unfoldable.
+-- | Note that given Enum is not included in the result.
 upFrom :: forall a u. Enum a => Unfoldable u => a -> u a
 upFrom = unfoldr (map diag <<< succ)
 
+-- | Results in all successors of given Enum (including itself)
+-- | in some NonEmpty unfoldable.
+upFromIncluding :: ∀ a u. Enum a => Unfoldable u => a -> NonEmpty u a
+upFromIncluding x = x :| upFrom x
+
 downFrom :: forall a u. Enum a => Unfoldable u => a -> u a
 downFrom = unfoldr (map diag <<< pred)
 

test/Test/Data/Enum.purs

@@ -7,9 +7,10 @@ import Control.Monad.Eff.Console (CONSOLE, log)
 
 import Data.Newtype (unwrap)
 import Data.Enum (class Enum, class BoundedEnum, defaultToEnum, defaultFromEnum,
-                  defaultCardinality, enumFromTo, enumFromThenTo, upFrom,
+                  defaultCardinality, enumFromTo, enumFromThenTo, upFrom, upFromIncluding,
                   downFrom, toEnum, fromEnum, Cardinality, cardinality)
 import Data.Maybe (Maybe(..))
+import Data.NonEmpty ((:|))
 import Data.Either (Either(..))
 
 import Test.Assert (ASSERT, assert)
@@ -61,6 +62,11 @@ testEnum = do
   assert $ upFrom D == [      E]
   assert $ upFrom E == [       ]
 
+  log "upFromIncluding"
+  assert $ upFromIncluding B == B :| [C, D, E]
+  assert $ upFromIncluding D == D :| [      E]
+  assert $ upFromIncluding E == E :| [       ]
+
   log "downFrom"
   assert $ downFrom D == [C, B, A]
   assert $ downFrom B == [      A]
@@ -81,4 +87,3 @@ testEnum = do
   assert $ fromEnum (Left false :: Either Boolean T) == 0
   assert $ fromEnum (Left true :: Either Boolean T) == 1
   assert $ fromEnum (Right B :: Either Boolean T) == 3
-