Expose getIndex from Array.Generic

composewell · May 24, 2023 · dea3d5f · dea3d5f
1 parent b608366
commit dea3d5f
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diff --git a/core/src/Streamly/Data/Array/Generic.hs b/core/src/Streamly/Data/Array/Generic.hs
@@ -31,6 +31,7 @@ module Streamly.Data.Array.Generic
 
     -- * Random Access
     , A.length
+    , A.getIndex
 
     -- -- * Folding Arrays
     -- , A.streamFold

diff --git a/core/src/Streamly/Internal/Data/Array/Generic.hs b/core/src/Streamly/Internal/Data/Array/Generic.hs
@@ -38,6 +38,7 @@ module Streamly.Internal.Data.Array.Generic
 
     -- * Random Access
     , getIndexUnsafe
+    , getIndex
     , getSliceUnsafe
     , strip
     )
@@ -208,6 +209,16 @@ getIndexUnsafe :: Int -> Array a -> a
 getIndexUnsafe i arr =
     unsafePerformIO $ MArray.getIndexUnsafe i (unsafeThaw arr)
 
+invalidIndex :: String -> Int -> a
+invalidIndex label i =
+    error $ label ++ ": invalid array index " ++ show i
+
+getIndex :: Int -> Array a -> a
+getIndex i arr@Array {..} =
+    if i >= 0 && i < arrLen
+    then getIndexUnsafe i arr
+    else invalidIndex "getIndex" i
+
 {-# INLINE writeLastN #-}
 writeLastN :: MonadIO m => Int -> Fold m a (Array a)
 writeLastN n = FL.rmapM f (RB.writeLastN n)