foldl1

A variant of foldl that has no base case, and thus may only be applied to non-empty structures. This function is non-total and will raise a runtime exception if the structure happens to be empty.

foldl1 f = foldl1 f . toList

Examples

Basic usage:

>>> foldl1 (+) [1..4]
10

>>> foldl1 (+) []
*** Exception: Prelude.foldl1: empty list

>>> foldl1 (+) Nothing
*** Exception: foldl1: empty structure

>>> foldl1 (-) [1..4]
-8

>>> foldl1 (&&) [True, False, True, True]
False

>>> foldl1 (||) [False, False, True, True]
True

>>> foldl1 (+) [1..]
* Hangs forever *

A variant of foldlMap1 where the leftmost element maps to itself.

foldl1 is a variant of foldl that has no starting value argument, and thus must be applied to non-empty lists. Note that unlike foldl, the accumulated value must be of the same type as the list elements.

>>> foldl1 (+) [1..4]
10

>>> foldl1 (+) []
*** Exception: Prelude.foldl1: empty list

>>> foldl1 (-) [1..4]
-8

>>> foldl1 (&&) [True, False, True, True]
False

>>> foldl1 (||) [False, False, True, True]
True

>>> foldl1 (+) [1..]
* Hangs forever *

foldl1 is a variant of foldl that has no starting value argument, and thus must be applied to non-empty ByteStrings. An exception will be thrown in the case of an empty ByteString.

foldl1 is a variant of foldl that has no starting value argument, and thus must be applied to non-empty ByteStrings.

foldl1 is a variant of foldl that has no starting value argument, and thus must be applied to non-empty ByteStrings.

foldl1 is a variant of foldl that has no starting value argument, and thus must be applied to non-empty ShortByteStrings. An exception will be thrown in the case of an empty ShortByteString.

O(n) A variant of foldl that has no starting value argument, and thus must be applied to a non-empty Text.

foldl1 is a variant of foldl that has no starting value argument, and thus must be applied to non-empty Streams. Properties

foldl1 f . stream = foldl1 f

A strict left fold with no starting value. Returns Nothing when the stream is empty. Subject to fusion

foldl1 is a variant of foldl that has no starting value argument, and thus must be applied to non-empty ByteStrings.

foldl1 is a variant of foldl that has no starting value argument, and thus must be applied to non-empty ByteStrings. An exception will be thrown in the case of an empty ByteString.

A variant of foldl that has no base case, and thus may only be applied to non-empty structures.

foldl1 f = foldl1 f . toList

O(n) A variant of foldl that has no starting value argument, and thus must be applied to a non-empty Text. Subject to fusion.

O(n) Left fold on non-empty vectors

O(n) Left fold on non-empty vectors

O(n) Left fold on non-empty vectors

O(n) Left fold on non-empty vectors

Reduces the characters of the ShortText with the binary operator.

>>> foldl1 max "abcdcba"
'd'

>>> foldl1 const "abcd"
'a'

>>> foldl1 (flip const) "abcd"
'd'

Note: Will throw an error exception if index is out of bounds.

A variant of foldl with no base case. Requires at least 1 list element.

O(n) A variant of foldl that has no starting value argument, and thus must be applied to a non-empty JSString. Subject to fusion.