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Within LTS Haskell 24.2 (ghc-9.10.2)

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1. head :: HasCallStack => [a] -> a

   base	Prelude

   Extract the first element of a list, which must be non-empty. To disable the warning about partiality put {-# OPTIONS_GHC -Wno-x-partial -Wno-unrecognised-warning-flags #-} at the top of the file. To disable it throughout a package put the same options into ghc-options section of Cabal file. To disable it in GHCi put :set -Wno-x-partial -Wno-unrecognised-warning-flags into ~/.ghci config file. See also the migration guide.

   Examples

   >>> head [1, 2, 3]
   1
   

   >>> head [1..]
   1
   

   >>> head []
   *** Exception: Prelude.head: empty list
   

2. head :: HasCallStack => [a] -> a

   base	Data.List

   Extract the first element of a list, which must be non-empty. To disable the warning about partiality put {-# OPTIONS_GHC -Wno-x-partial -Wno-unrecognised-warning-flags #-} at the top of the file. To disable it throughout a package put the same options into ghc-options section of Cabal file. To disable it in GHCi put :set -Wno-x-partial -Wno-unrecognised-warning-flags into ~/.ghci config file. See also the migration guide.

   Examples

   >>> head [1, 2, 3]
   1
   

   >>> head [1..]
   1
   

   >>> head []
   *** Exception: Prelude.head: empty list
   

3. head :: Foldable1 t => t a -> a

   base	Data.Foldable1

   The first element of a non-empty structure.

   >>> head (1 :| [2, 3, 4])
   1
   

4. head :: NonEmpty a -> a

   base	Data.List.NonEmpty

   Extract the first element of the stream.

5. head :: HasCallStack => [a] -> a

   base	GHC.List

   Extract the first element of a list, which must be non-empty. To disable the warning about partiality put {-# OPTIONS_GHC -Wno-x-partial -Wno-unrecognised-warning-flags #-} at the top of the file. To disable it throughout a package put the same options into ghc-options section of Cabal file. To disable it in GHCi put :set -Wno-x-partial -Wno-unrecognised-warning-flags into ~/.ghci config file. See also the migration guide.

   Examples

   >>> head [1, 2, 3]
   1
   

   >>> head [1..]
   1
   

   >>> head []
   *** Exception: Prelude.head: empty list
   

6. head :: HasCallStack => ByteString -> Word8

   bytestring	Data.ByteString

   O(1) Extract the first element of a ByteString, which must be non-empty. An exception will be thrown in the case of an empty ByteString. This is a partial function, consider using uncons instead.

7. head :: ByteString -> Char

   bytestring	Data.ByteString.Char8

   O(1) Extract the first element of a ByteString, which must be non-empty.

8. head :: HasCallStack => ByteString -> Word8

   bytestring	Data.ByteString.Lazy

   O(1) Extract the first element of a ByteString, which must be non-empty. This is a partial function, consider using uncons instead.

9. head :: ByteString -> Char

   bytestring	Data.ByteString.Lazy.Char8

   O(1) Extract the first element of a ByteString, which must be non-empty.

10. head :: HasCallStack => ShortByteString -> Word8

    bytestring	Data.ByteString.Short

    O(1) Extract the first element of a ShortByteString, which must be non-empty. An exception will be thrown in the case of an empty ShortByteString. This is a partial function, consider using uncons instead.

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