---
slug: /experiments/any-variables/
---

import Tabs from '@theme/Tabs';
import TabItem from '@theme/TabItem';

# Any Variables (#1415)

:::caution

All experimental features are subject to breaking changes and/or removal _at any
time_. We strongly recommend that you do not use these features in a production
environment. They are intended for testing and feedback only.

:::

Currently, Task only supports string variables. This experiment allows you to
specify and use the following variable types:

- `string`
- `bool`
- `int`
- `float`
- `array`
- `map`

This allows you to have a lot more flexibility in how you use variables in
Task's templating engine. There are two active proposals for this experiment.
Click on the tabs below to switch between them.

<Tabs defaultValue="1" queryString="proposal"
  values={[
    {label: 'Proposal 1', value: '1'},
    {label: 'Proposal 2', value: '2'}
  ]}>

<TabItem value="1">

:::warning

This experiment proposal breaks the following functionality:

- Dynamically defined variables (using the `sh` keyword)

:::

:::info

To enable this experiment, set the environment variable:
`TASK_X_ANY_VARIABLES=1`. Check out [our guide to enabling experiments
][enabling-experiments] for more information.

:::

## Maps

This proposal removes support for the `sh` keyword in favour of a new syntax for
dynamically defined variables, This allows you to define a map directly as you
would for any other type:

```yaml
version: 3

tasks:
  foo:
    vars:
      FOO: {a: 1, b: 2, c: 3} # <-- Directly defined map on the `FOO` key
    cmds:
      - 'echo {{.FOO.a}}'
```

## Migration

Taskfiles with dynamically defined variables via the `sh` subkey will no longer
work with this experiment enabled. In order to keep using dynamically defined
variables, you will need to migrate your Taskfile to use the new syntax.

Previously, you might have defined a dynamic variable like this:

```yaml
version: 3

tasks:
  foo:
    vars:
      CALCULATED_VAR:
        sh: 'echo hello'
    cmds:
      - 'echo {{.CALCULATED_VAR}}'
```

With this experiment enabled, you will need to remove the `sh` subkey and define
your command as a string that begins with a `$`. This will instruct Task to
interpret the string as a command instead of a literal value and the variable
will be populated with the output of the command. For example:

```yaml
version: 3

tasks:
  foo:
    vars:
      CALCULATED_VAR: '$echo hello'
    cmds:
      - 'echo {{.CALCULATED_VAR}}'
```

If your current Taskfile contains a string variable that begins with a `$`, you
will now need to escape the `$` with a backslash (`\`) to stop Task from
executing it as a command.

</TabItem>

<TabItem value="2">

:::info

To enable this experiment, set the environment variable:
`TASK_X_ANY_VARIABLES=2`. Check out [our guide to enabling experiments
][enabling-experiments] for more information.

:::

## Maps

This proposal maintains backwards-compatibility and the `sh` subkey and adds
another new `map` subkey for defining map variables:

```yaml
version: 3

tasks:
  foo:
    vars:
      FOO:
        map: {a: 1, b: 2, c: 3} # <-- Defined using the `map' subkey instead of directly on 'FOO'
      BAR: true # <-- Other types of variables are still defined directly on the key
      BAZ:
        sh: 'echo Hello Task' # <-- The `sh` subkey is still supported
    cmds:
      - 'echo {{.FOO.a}}'
```

## Parsing JSON and YAML

In addition to the new `map` keyword, this proposal also adds support for the
`json` and `yaml` keywords for parsing JSON and YAML strings into real
objects/arrays. This is similar to the `fromJSON` template function, but means
that you only have to parse the JSON/YAML once when you declare the variable,
instead of every time you want to access a value.

Before:

```yaml
version: 3

tasks:
  foo:
    vars:
      FOO: '{"a": 1, "b": 2, "c": 3}' # <-- JSON string
    cmds:
      - 'echo {{(fromJSON .FOO).a}}' # <-- Parse JSON string every time you want to access a value
      - 'echo {{(fromJSON .FOO).b}}'
```

After:

```yaml
version: 3

tasks:
  foo:
    vars:
      FOO:
        json: '{"a": 1, "b": 2, "c": 3}' # <-- JSON string parsed once
    cmds:
      - 'echo {{.FOO.a}}' # <-- Access values directly
      - 'echo {{.FOO.b}}'
```

## Variables by reference

Lastly, this proposal adds support for defining and passing variables by
reference. This is really important now that variables can be types other than a
string. Previously, to send a variable from one task to another, you would have
to use the templating system to pass it:

```yaml
version: 3

tasks:
  foo:
    vars:
      FOO: [A, B, C] # <-- FOO is defined as an array
    cmds:
      - task: bar
        vars:
          FOO: '{{.FOO}}' # <-- FOO gets converted to a string when passed to bar
  bar:
    cmds:
      - 'echo {{index .FOO 0}}' # <-- FOO is a string so the task outputs '91' which is the ASCII code for '[' instead of the expected 'A'
```

Unfortunately, this results in the value always being passed as a string as this
is the output type of the templater and operations on the passed variable may
not behave as expected. With this proposal, you can now pass variables by
reference using the `ref` subkey:

```yaml
version: 3

tasks:
  foo:
    vars:
      FOO: [A, B, C] # <-- FOO is defined as an array
    cmds:
      - task: bar
        vars:
          FOO:
            ref: FOO # <-- FOO gets passed by reference to bar and maintains its type
  bar:
    cmds:
      - 'echo {{index .FOO 0}}' # <-- FOO is still a map so the task outputs 'A' as expected
```

This means that the type of the variable is maintained when it is passed to
another Task. This also works the same way when calling `deps` and when defining
a variable and can be used in any combination:

```yaml
version: 3

tasks:
  foo:
    vars:
      FOO: [A, B, C] # <-- FOO is defined as an array
      BAR:
        ref: FOO # <-- BAR is defined as a reference to FOO
    deps:
      - task: bar
        vars:
          BAR:
            ref: BAR # <-- BAR gets passed by reference to bar and maintains its type
  bar:
    cmds:
      - 'echo {{index .BAR 0}}' # <-- BAR still refers to FOO so the task outputs 'A'
```

</TabItem></Tabs>

---

## Common to both proposals

Both proposals add support for all other variable types by directly defining
them in the Taskfile. For example:

### Evaluating booleans

```yaml
version: 3

tasks:
  foo:
    vars:
      BOOL: false
    cmds:
      - '{{if .BOOL}}echo foo{{end}}'
```

### Arithmetic

```yaml
version: 3

tasks:
  foo:
    vars:
      INT: 10
      FLOAT: 3.14159
    cmds:
      - 'echo {{add .INT .FLOAT}}'
```

### Ranging

```yaml
version: 3

tasks:
  foo:
    vars:
      ARRAY: [1, 2, 3]
    cmds:
      - 'echo {{range .ARRAY}}{{.}}{{end}}'
```

There are many more templating functions which can be used with the new types of
variables. For a full list, see the [slim-sprig][slim-sprig] documentation.

## Looping over variables

Previously, you would have to use a delimiter separated string to loop over an
arbitrary list of items in a variable and split them by using the `split` subkey
to specify the delimiter:

```yaml
version: 3

tasks:
  foo:
    vars:
      LIST: 'foo,bar,baz'
    cmds:
      - for:
          var: LIST
          split: ','
        cmd: echo {{.ITEM}}
```

Both of these proposals add support for looping over "collection-type" variables
using the `for` keyword, so now you are able to loop over a map/array variable
directly:

```yaml
version: 3

tasks:
  foo:
    vars:
      LIST: [foo, bar, baz]
    cmds:
      - for:
          var: LIST
        cmd: echo {{.ITEM}}
```

When looping over a map we also make an additional `{{.KEY}}` variable availabe
that holds the string value of the map key. Remember that maps are unordered, so
the order in which the items are looped over is random.

<!-- prettier-ignore-start -->
[enabling-experiments]: /experiments/#enabling-experiments
[slim-sprig]: https://go-task.github.io/slim-sprig/
<!-- prettier-ignore-end -->
