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# DA.Either

> Reference documentation for Daml module DA.Either.

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<span id="module-da-either-91022" />

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

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

  <p class="x2mdx-ref-summary">The Either type represents values with two possibilities.</p>

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    <span class="x2mdx-ref-badge x2mdx-ref-badge--protocol">Daml</span>
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    <div class="x2mdx-ref-meta-item">
      <dt>Module</dt>
      <dd>DA.Either</dd>
    </div>

    <div class="x2mdx-ref-meta-item">
      <dt>Latest release</dt>
      <dd>3.5.7</dd>
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  </dl>
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## Functions

<span id="function-da-either-lefts-59601" />

### `lefts`

`lefts` : \[[`Either`](/appdev/reference/daml-standard-library/prelude#type-da-types-either-56020) `a` `b`] -> \[`a`]

Extracts all the `Left` elements from a list.

<span id="function-da-either-rights-20455" />

### `rights`

`rights` : \[[`Either`](/appdev/reference/daml-standard-library/prelude#type-da-types-either-56020) `a` `b`] -> \[`b`]

Extracts all the `Right` elements from a list.

<span id="function-da-either-partitioneithers-19904" />

### `partitionEithers`

`partitionEithers` : \[[`Either`](/appdev/reference/daml-standard-library/prelude#type-da-types-either-56020) `a` `b`] -> (\[`a`], \[`b`])

Partitions a list of `Either` into two lists, the `Left` and
`Right` elements respectively. Order is maintained.

<span id="function-da-either-isleft-96021" />

### `isLeft`

`isLeft` : [`Either`](/appdev/reference/daml-standard-library/prelude#type-da-types-either-56020) `a` `b` -> [`Bool`](/appdev/reference/daml-standard-library/prelude#type-ghc-types-bool-66265)

Return `True` if the given value is a `Left`-value, `False`
otherwise.

<span id="function-da-either-isright-36975" />

### `isRight`

`isRight` : [`Either`](/appdev/reference/daml-standard-library/prelude#type-da-types-either-56020) `a` `b` -> [`Bool`](/appdev/reference/daml-standard-library/prelude#type-ghc-types-bool-66265)

Return `True` if the given value is a `Right`-value, `False`
otherwise.

<span id="function-da-either-fromleft-63875" />

### `fromLeft`

`fromLeft` : `a` -> [`Either`](/appdev/reference/daml-standard-library/prelude#type-da-types-either-56020) `a` `b` -> `a`

Return the contents of a `Left`-value, or a default value
in case of a `Right`-value.

<span id="function-da-either-fromright-27657" />

### `fromRight`

`fromRight` : `b` -> [`Either`](/appdev/reference/daml-standard-library/prelude#type-da-types-either-56020) `a` `b` -> `b`

Return the contents of a `Right`-value, or a default value
in case of a `Left`-value.

<span id="function-da-either-optionaltoeither-21876" />

### `optionalToEither`

`optionalToEither` : `a` -> [`Optional`](/appdev/reference/daml-standard-library/prelude#type-da-internal-prelude-optional-37153) `b` -> [`Either`](/appdev/reference/daml-standard-library/prelude#type-da-types-either-56020) `a` `b`

Convert a `Optional` value to an `Either` value, using the supplied
parameter as the `Left` value if the `Optional` is `None`.

<span id="function-da-either-eithertooptional-89140" />

### `eitherToOptional`

`eitherToOptional` : [`Either`](/appdev/reference/daml-standard-library/prelude#type-da-types-either-56020) `a` `b` -> [`Optional`](/appdev/reference/daml-standard-library/prelude#type-da-internal-prelude-optional-37153) `b`

Convert an `Either` value to a `Optional`, dropping any value in
`Left`.

<span id="function-da-either-maybetoeither-6635" />

### `maybeToEither`

`maybeToEither` : `a` -> [`Optional`](/appdev/reference/daml-standard-library/prelude#type-da-internal-prelude-optional-37153) `b` -> [`Either`](/appdev/reference/daml-standard-library/prelude#type-da-types-either-56020) `a` `b`

<span id="function-da-either-eithertomaybe-94811" />

### `eitherToMaybe`

`eitherToMaybe` : [`Either`](/appdev/reference/daml-standard-library/prelude#type-da-types-either-56020) `a` `b` -> [`Optional`](/appdev/reference/daml-standard-library/prelude#type-da-internal-prelude-optional-37153) `b`