head -package:blaze-html

Warning: This is a partial function, it throws an error on empty lists. Use pattern matching, uncons or listToMaybe instead. Consider refactoring to use Data.List.NonEmpty.

The first element of a non-empty structure.

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

Extract the first element of the stream.

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.

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

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

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.

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

O(1) Returns the first character of a Stream Char, which must be non-empty. This is a partial function, consider using uncons. Properties

head . stream = head

O(1) First element.

First element of the Bundle or error if empty

First element of the Bundle or error if empty

O(1) First element.

O(1) First element.

O(1) First element.

O(1) First element.

Take a single value from the stream, if available.

Take a single value from the stream, if available. Subject to fusion Since 0.3.0

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.

Return the next byte from the stream, if available. Since 0.3.0

Retrieve the first element from a Producer