> ## Documentation Index
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> Use this file to discover all available pages before exploring further.

# DA.NonEmpty

> Reference documentation for Daml module DA.NonEmpty.

<span id="module-da-nonempty-15701" />

# DA.NonEmpty

Type and functions for non-empty lists. This module re-exports many functions with

the same name as prelude list functions, so it is expected to import the module qualified.

For example, with the following import list you will have access to the `NonEmpty` type

and any functions on non-empty lists will be qualified, for example as `NE.append, NE.map, NE.foldl`:

```

import DA.NonEmpty (NonEmpty)

import qualified DA.NonEmpty as NE

```

## Module Snapshot

<CardGroup cols={2}>
  <Card title="Lifecycle">
    Stable.
  </Card>

  <Card title="Notices">
    Status: `active`
    Introduced in: `3.4.9`
    Removed in: `-`
    Warnings: `0`
    Deprecations: `0`
    Deprecated since: `-`
  </Card>
</CardGroup>

## Functions

<span id="function-da-nonempty-cons-63704" />

### `cons`

`cons` : `a` -> [`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010) `a` -> [`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010) `a`

Prepend an element to a non-empty list.

<span id="function-da-nonempty-append-34337" />

### `append`

`append` : [`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010) `a` -> [`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010) `a` -> [`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010) `a`

Append or concatenate two non-empty lists.

<span id="function-da-nonempty-map-69362" />

### `map`

`map` : (`a` -> `b`) -> [`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010) `a` -> [`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010) `b`

Apply a function over each element in the non-empty list.

<span id="function-da-nonempty-nonempty-24939" />

### `nonEmpty`

`nonEmpty` : \[`a`] -> [`Optional`](/appdev/reference/daml-standard-library/prelude#type-da-internal-prelude-optional-37153) ([`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010) `a`)

Turn a list into a non-empty list, if possible. Returns
`None` if the input list is empty, and `Some` otherwise.

<span id="function-da-nonempty-singleton-99101" />

### `singleton`

`singleton` : `a` -> [`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010) `a`

A non-empty list with a single element.

<span id="function-da-nonempty-tolist-15474" />

### `toList`

`toList` : [`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010) `a` -> \[`a`]

Turn a non-empty list into a list (by forgetting that it is not empty).

<span id="function-da-nonempty-reverse-64050" />

### `reverse`

`reverse` : [`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010) `a` -> [`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010) `a`

Reverse a non-empty list.

<span id="function-da-nonempty-find-73910" />

### `find`

`find` : (`a` -> [`Bool`](/appdev/reference/daml-standard-library/prelude#type-ghc-types-bool-66265)) -> [`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010) `a` -> [`Optional`](/appdev/reference/daml-standard-library/prelude#type-da-internal-prelude-optional-37153) `a`

Find an element in a non-empty list.

<span id="function-da-nonempty-deleteby-6333" />

### `deleteBy`

`deleteBy` : (`a` -> `a` -> [`Bool`](/appdev/reference/daml-standard-library/prelude#type-ghc-types-bool-66265)) -> `a` -> [`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010) `a` -> \[`a`]

The 'deleteBy' function behaves like 'delete', but takes a
user-supplied equality predicate.

<span id="function-da-nonempty-delete-59160" />

### `delete`

`delete` : [`Eq`](/appdev/reference/daml-standard-library/prelude#class-ghc-classes-eq-22713) `a` => `a` -> [`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010) `a` -> \[`a`]

Remove the first occurence of x from the non-empty list, potentially
removing all elements.

<span id="function-da-nonempty-foldl1-17561" />

### `foldl1`

`foldl1` : (`a` -> `a` -> `a`) -> [`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010) `a` -> `a`

Apply a function repeatedly to pairs of elements from a non-empty list,
from the left. For example, `foldl1 (+) (NonEmpty 1 [2,3,4]) = ((1 + 2) + 3) + 4`.

<span id="function-da-nonempty-foldr1-43627" />

### `foldr1`

`foldr1` : (`a` -> `a` -> `a`) -> [`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010) `a` -> `a`

Apply a function repeatedly to pairs of elements from a non-empty list,
from the right. For example, `foldr1 (+) (NonEmpty 1 [2,3,4]) = 1 + (2 + (3 + 4))`.

<span id="function-da-nonempty-foldr-65043" />

### `foldr`

`foldr` : (`a` -> `b` -> `b`) -> `b` -> [`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010) `a` -> `b`

Apply a function repeatedly to pairs of elements from a non-empty list,
from the right, with a given initial value. For example,
`foldr (+) 0 (NonEmpty 1 [2,3,4]) = 1 + (2 + (3 + (4 + 0)))`.

<span id="function-da-nonempty-foldra-91227" />

### `foldrA`

`foldrA` : [`Action`](/appdev/reference/daml-standard-library/prelude#class-da-internal-prelude-action-68790) `m` => (`a` -> `b` -> `m` `b`) -> `b` -> [`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010) `a` -> `m` `b`

The same as `foldr` but running an action each time.

<span id="function-da-nonempty-foldr1a-13463" />

### `foldr1A`

`foldr1A` : [`Action`](/appdev/reference/daml-standard-library/prelude#class-da-internal-prelude-action-68790) `m` => (`a` -> `a` -> `m` `a`) -> [`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010) `a` -> `m` `a`

The same as `foldr1` but running an action each time.

<span id="function-da-nonempty-foldl-91113" />

### `foldl`

`foldl` : (`b` -> `a` -> `b`) -> `b` -> [`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010) `a` -> `b`

Apply a function repeatedly to pairs of elements from a non-empty list,
from the left, with a given initial value. For example,
`foldl (+) 0 (NonEmpty 1 [2,3,4]) = (((0 + 1) + 2) + 3) + 4`.

<span id="function-da-nonempty-foldla-69961" />

### `foldlA`

`foldlA` : [`Action`](/appdev/reference/daml-standard-library/prelude#class-da-internal-prelude-action-68790) `m` => (`b` -> `a` -> `m` `b`) -> `b` -> [`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010) `a` -> `m` `b`

The same as `foldl` but running an action each time.

<span id="function-da-nonempty-foldl1a-63665" />

### `foldl1A`

`foldl1A` : [`Action`](/appdev/reference/daml-standard-library/prelude#class-da-internal-prelude-action-68790) `m` => (`a` -> `a` -> `m` `a`) -> [`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010) `a` -> `m` `a`

The same as `foldl1` but running an action each time.

## Orphan Typeclass Instances

* instance [`Eq`](/appdev/reference/daml-standard-library/prelude#class-ghc-classes-eq-22713) `a` => [`Eq`](/appdev/reference/daml-standard-library/prelude#class-ghc-classes-eq-22713) ([`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010) `a`)

* instance [`Show`](/appdev/reference/daml-standard-library/prelude#class-ghc-show-show-65360) `a` => [`Show`](/appdev/reference/daml-standard-library/prelude#class-ghc-show-show-65360) ([`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010) `a`)

* instance [`Ord`](/appdev/reference/daml-standard-library/prelude#class-ghc-classes-ord-6395) `a` => [`Ord`](/appdev/reference/daml-standard-library/prelude#class-ghc-classes-ord-6395) ([`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010) `a`)

* instance [`GetField`](/appdev/reference/daml-standard-library/da-record#class-da-internal-record-getfield-53979) `hd` ([`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010) `a`) `a`

* instance [`SetField`](/appdev/reference/daml-standard-library/da-record#class-da-internal-record-setfield-4311) `hd` ([`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010) `a`) `a`

* instance [`GetField`](/appdev/reference/daml-standard-library/da-record#class-da-internal-record-getfield-53979) `tl` ([`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010) `a`) \[`a`]

* instance [`SetField`](/appdev/reference/daml-standard-library/da-record#class-da-internal-record-setfield-4311) `tl` ([`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010) `a`) \[`a`]

* instance [`Semigroup`](/appdev/reference/daml-standard-library/prelude#class-da-internal-prelude-semigroup-78998) ([`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010) `a`)

* instance [`Functor`](/appdev/reference/daml-standard-library/prelude#class-ghc-base-functor-31205) [`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010)

* instance [`Applicative`](/appdev/reference/daml-standard-library/prelude#class-da-internal-prelude-applicative-9257) [`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010)

* instance [`Action`](/appdev/reference/daml-standard-library/prelude#class-da-internal-prelude-action-68790) [`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010)

* instance [`Foldable`](/appdev/reference/daml-standard-library/da-foldable#class-da-foldable-foldable-25994) [`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010)

* instance [`Traversable`](/appdev/reference/daml-standard-library/da-traversable#class-da-traversable-traversable-18144) [`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010)

* instance [`IsParties`](/appdev/reference/daml-standard-library/prelude#class-da-internal-template-functions-isparties-53750) ([`NonEmpty`](/appdev/reference/daml-standard-library/da-nonempty-types#type-da-nonempty-types-nonempty-16010) [`Party`](/appdev/reference/daml-standard-library/prelude#type-da-internal-lf-party-57932))