Hoogle Search

Within LTS Haskell 22.22 (ghc-9.6.5)

Note that Stackage only displays results for the latest LTS and Nightly snapshot. Learn more.

Exact lookup

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

   base	Prelude

   Extract the first element of a list, which must be non-empty.

   >>> head [1, 2, 3]
   1
   
   >>> head [1..]
   1
   
   >>> head []
   *** Exception: Prelude.head: empty list
   

   WARNING: This function is partial. You can use case-matching, uncons or listToMaybe instead.

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

   base	Data.List

   Extract the first element of a list, which must be non-empty.

   >>> head [1, 2, 3]
   1
   
   >>> head [1..]
   1
   
   >>> head []
   *** Exception: Prelude.head: empty list
   

   WARNING: This function is partial. You can use case-matching, uncons or listToMaybe instead.

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.

   >>> head [1, 2, 3]
   1
   
   >>> head [1..]
   1
   
   >>> head []
   *** Exception: Prelude.head: empty list
   

   WARNING: This function is partial. You can use case-matching, uncons or listToMaybe instead.

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

   base	GHC.OldList

   Extract the first element of a list, which must be non-empty.

   >>> head [1, 2, 3]
   1
   
   >>> head [1..]
   1
   
   >>> head []
   *** Exception: Prelude.head: empty list
   

   WARNING: This function is partial. You can use case-matching, uncons or listToMaybe instead.

7. 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.

8. head :: ByteString -> Char

   bytestring	Data.ByteString.Char8

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

9. 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.

10. head :: ByteString -> Char

    bytestring	Data.ByteString.Lazy.Char8

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

Page 1 of many | Next