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# DA.NonEmpty

> Reference documentation for Daml module DA.NonEmpty.

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

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  <p class="x2mdx-ref-eyebrow">Daml module</p>

  <h1 class="x2mdx-ref-title">DA.NonEmpty</h1>

  <p class="x2mdx-ref-summary">Type and functions for non-empty lists. This module re-exports many functions with</p>

  <div class="x2mdx-ref-badges">
    <span class="x2mdx-ref-badge x2mdx-ref-badge--protocol">Daml</span>

    <a class="x2mdx-ref-badge x2mdx-ref-badge--added" href="#history-added-3-4-9">Added 3.4.9</a>
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  <dl class="x2mdx-ref-meta-grid">
    <div class="x2mdx-ref-meta-item">
      <dt>Module</dt>
      <dd>DA.NonEmpty</dd>
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    <div class="x2mdx-ref-meta-item">
      <dt>Latest release</dt>
      <dd>3.5.7</dd>
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## 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))

## History

<div class="x2mdx-ref-history" aria-label="Reference history">
  <div class="x2mdx-ref-history-event x2mdx-ref-history-event--introduced" id="history-added-3-4-9">
    <div class="x2mdx-ref-history-event-head">
      <span class="x2mdx-ref-history-event-label">Added</span>
      <code class="x2mdx-ref-history-event-version">3.4.9</code>
    </div>
  </div>
</div>