Feature: sconcat and stimes.

benchmarks/haskell/Benchmarks/Pure.hs

@@ -26,6 +26,8 @@ import qualified Data.Text.Encoding as T
 import qualified Data.Text.Lazy as TL
 import qualified Data.Text.Lazy.Builder as TB
 import qualified Data.Text.Lazy.Encoding as TL
+import Data.Semigroup
+import Data.List.NonEmpty (NonEmpty((:|)))
 
 data Env = Env
     { bsa :: !BS.ByteString
@@ -83,6 +85,14 @@ benchmark kind ~Env{..} =
             [ benchT   $ nf T.concat tl
             , benchTL  $ nf TL.concat tll
             ]
+        , bgroup "sconcat"
+            [ benchT   $ nf sconcat (T.empty :| tl)
+            , benchTL  $ nf sconcat (TL.empty :| tll)
+            ]
+        , bgroup "stimes"
+            [ benchT   $ nf (stimes (10 :: Int)) ta
+            , benchTL  $ nf (stimes (10 :: Int)) tla
+            ]
         , bgroup "cons"
             [ benchT   $ nf (T.cons c) ta
             , benchTL  $ nf (TL.cons c) tla

src/Data/Text.hs

@@ -362,6 +362,16 @@ instance Read Text where
 instance Semigroup Text where
     (<>) = append
 
+    -- | Beware: this function will evaluate to error if the given number does
+    -- not fit into an @Int@.
+    stimes howManyTimes =
+        let howManyTimesInt = P.fromIntegral howManyTimes :: Int
+        in  if P.fromIntegral howManyTimesInt == howManyTimes
+            then replicate howManyTimesInt
+            else P.error "Data.Text.stimes: given number does not fit into an Int!"
+
+    sconcat = concat . NonEmptyList.toList
+
 instance Monoid Text where
     mempty  = empty
     mappend = (<>)

tests/Tests/Properties.hs

@@ -17,6 +17,7 @@ import Tests.Properties.Read (testRead)
 import Tests.Properties.Text (testText)
 import Tests.Properties.Transcoding (testTranscoding)
 import Tests.Properties.Validate (testValidate)
+import Tests.Properties.CornerCases (testCornerCases)
 
 tests :: TestTree
 tests =
@@ -30,5 +31,6 @@ tests =
     testBuilder,
     testLowLevel,
     testRead,
+    testCornerCases,
     testValidate
   ]

tests/Tests/Properties/CornerCases.hs

@@ -0,0 +1,35 @@
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE TypeApplications #-}
+
+-- | Check that the definitions that are partial crash in the expected ways or
+-- return sensible defaults.
+module Tests.Properties.CornerCases (testCornerCases) where
+
+import Control.Exception
+import Data.Either
+import Data.Semigroup
+import Data.Text
+import Test.QuickCheck
+import Test.Tasty (TestTree, testGroup)
+import Test.Tasty.QuickCheck (testProperty)
+import Tests.QuickCheckUtils ()
+
+testCornerCases :: TestTree
+testCornerCases =
+  testGroup
+    "corner cases"
+    [ testGroup
+        "stimes"
+        $ let specimen = stimes :: Integer -> Text -> Text
+          in  [ testProperty
+                  "given a negative number, return empty text"
+                  $ \(Negative number) text -> specimen number text == ""
+              , testProperty
+                  "given a number that does not fit into Int, evaluate to error call"
+                  $ \(NonNegative number) text ->
+                    (ioProperty . fmap isLeft . try @ErrorCall . evaluate) $
+                      specimen
+                        (fromIntegral (number :: Int) + fromIntegral (maxBound :: Int) + 1)
+                        text
+              ]
+    ]

text.cabal

@@ -275,6 +275,7 @@ test-suite tests
     Tests.Properties.Substrings
     Tests.Properties.Text
     Tests.Properties.Transcoding
+    Tests.Properties.CornerCases
     Tests.Properties.Validate
     Tests.QuickCheckUtils
     Tests.RebindableSyntaxTest