---
title: Types
description: Overview of the standard types in the Nextflow standard library, including primitive types, collections, records, and dataflow types.
---

# Types

The Nextflow standard library defines the types that are available in a pipeline. You can use these types to annotate pipeline parameters, process inputs and outputs, and workflow inputs and outputs. See [Static typing][static-typing-page] for an overview.

## Primitive types

| Page | Description |
| ---- | ----------- |
| [Boolean][stdlib-types-boolean] | `true` or `false`. |
| [Float][stdlib-types-float] | A floating-point number. |
| [Integer][stdlib-types-integer] | A whole number. |
| [String][stdlib-types-string] | An immutable sequence of characters. |

## Collection types

| Page | Description |
| ---- | ----------- |
| [Bag\<E\>][stdlib-types-bag] | An unordered collection of values. |
| [Iterable\<E\>][stdlib-types-iterable] | The trait implemented by collection types that support iteration. |
| [List\<E\>][stdlib-types-list] | An ordered collection of values. |
| [Set\<E\>][stdlib-types-set] | An unordered collection of unique values. |

## Composite types

| Page | Description |
| ---- | ----------- |
| [Map\<K,V\>][stdlib-types-map] | A mapping of key-value pairs. |
| [Record][stdlib-types-record] | An immutable map of fields to values, where each value can have its own type. |
| [Tuple][stdlib-types-tuple] | A fixed sequence of values, where each value can have its own type. |

## Dataflow types

| Page | Description |
| ---- | ----------- |
| [Channel\<E\>][stdlib-types-channel] | An asynchronous sequence of values. |
| [Value\<V\>][stdlib-types-value] | An asynchronous value. |

## Other types

| Page | Description |
| ---- | ----------- |
| [Duration][stdlib-types-duration] | A duration of time. |
| [MemoryUnit][stdlib-types-memory-unit] | A quantity of bytes. |
| [Path][stdlib-types-path] | A handle for files, directories, and URLs. |
| [VersionNumber][stdlib-types-version-number] | A semantic or calendar version number. |

## See also

- [Namespaces][stdlib-namespaces-page]: The constants and functions that return these types.
- [Semantics][semantics-values]: How Nextflow evaluates values and expressions that use these types.

[semantics-values]: ./semantics#values
[static-typing-page]: ../static-typing
[stdlib-namespaces-page]: ./stdlib-namespaces
[stdlib-types-bag]: ./stdlib-types/bag
[stdlib-types-boolean]: ./stdlib-types/boolean
[stdlib-types-channel]: ./stdlib-types/channel
[stdlib-types-duration]: ./stdlib-types/duration
[stdlib-types-float]: ./stdlib-types/float
[stdlib-types-integer]: ./stdlib-types/integer
[stdlib-types-iterable]: ./stdlib-types/iterable
[stdlib-types-list]: ./stdlib-types/list
[stdlib-types-map]: ./stdlib-types/map
[stdlib-types-memory-unit]: ./stdlib-types/memory-unit
[stdlib-types-path]: ./stdlib-types/path
[stdlib-types-record]: ./stdlib-types/record
[stdlib-types-set]: ./stdlib-types/set
[stdlib-types-string]: ./stdlib-types/string
[stdlib-types-tuple]: ./stdlib-types/tuple
[stdlib-types-value]: ./stdlib-types/value
[stdlib-types-version-number]: ./stdlib-types/version-number