Sass meta.module-functions()

Intermediate
9 min read
Updated: Nov 2026
5 examples
Dart Sass 1.23+
Sass meta.module-functions listing functions from a loaded module as a map
Definition

Definition and Usage

meta.module-functions($module) returns a map of every function defined in $module—keys are function names, values are function values. Dart Sass only. Load with @use "sass:meta".

Official sample idea.

After @use "functions", meta.call(map.get(meta.module-functions("functions"), "pow"), 3, 4) → 81.

$module matches a namespace.

Pass a string matching a @use namespace in the current file (e.g. "functions", "math"), or a module value.

Map values are not CSS.

Run them with meta.call. Peek at names with map.keys + meta.inspect.

Syntax

Syntax

SCSS
@use "sass:map";
@use "sass:meta";
@use "functions";

meta.module-functions($module); //=> map

// Official pattern
meta.call(
  map.get(meta.module-functions("functions"), "pow"),
  3,
  4
); // 81

// Module API — Dart Sass only

Pattern: @use the module → module-functions for the catalog → map.get / map.has-key → meta.call.

Reference

Map Shape and Calling

What you get back and how to use it:

PieceMeaningTypical next step
Map keysFunction names as stringsmap.keys / map.has-key
Map valuesFunction valuesmeta.call($fn, $args...)
$module stringMust match this file’s @use namespace"functions", "math", …
vs function-existsOne name yes/noUse exists for a single check
vs get-functionOne function by nameUse module-functions for the full catalog
Sibling catalogs.

meta.module-mixins and meta.module-variables do the same for mixins and variables.

Code

SCSS Examples

Examples target Dart Sass with @use "sass:meta". Open View Compiled CSS for verified output (matches official Sass docs samples where shown).

Example 1 — List Function Names in a Module

Inspect map.keys so you can see the catalog without printing function values.

SCSS
@function pow($base, $exponent) {
  $result: 1;
  @for $_ from 1 through $exponent {
    $result: $result * $base;
  }
  @return $result;
}

@function double($n) {
  @return $n * 2;
}
SCSS
@use "sass:map";
@use "sass:meta";
@use "functions";

$fns: meta.module-functions("functions");

.probe {
  --keys: #{meta.inspect(map.keys($fns))};
}

How It Works

  1. @use "functions" loads the partial.
  2. module-functions returns the map.
  3. map.keys lists the names.
  4. inspect peeks at them for learning / debug.

Example 2 — Official map.get + meta.call

Pick pow from the map and compute 34 = 81.

SCSS
@use "sass:map";
@use "sass:meta";
@use "functions";

.result {
  width: meta.call(
    map.get(meta.module-functions("functions"), "pow"),
    3,
    4
  ) * 1px;
}

How It Works

  1. map.get picks the pow function value.
  2. meta.call runs it with 3 and 4.
  3. Result is 81, then multiplied by 1px.
  4. Matches the official Sass docs sample.

Example 3 — Probe sass:math

After @use "sass:math", use map.has-key on the catalog.

SCSS
@use "sass:map";
@use "sass:meta";
@use "sass:math";

$math-fns: meta.module-functions("math");

.probe {
  --has-div: #{map.has-key($math-fns, "div")};
  --has-pow: #{map.has-key($math-fns, "pow")};
  --has-nope: #{map.has-key($math-fns, "nope")};
}

How It Works

  1. Built-in modules work the same way.
  2. "math" must match this file’s @use namespace.
  3. div and pow are present.
  4. Unknown names return false from has-key.

Example 4 — Count Functions in a Module

Combine map.keys with list.length for a simple inventory.

SCSS
@use "sass:list";
@use "sass:map";
@use "sass:meta";
@use "functions";

$fns: meta.module-functions("functions");

.count {
  --n: #{list.length(map.keys($fns))};
}

How It Works

  1. _functions.scss exports pow and double.
  2. map.keys builds the name list.
  3. list.length counts them.
  4. Result is 2.

Example 5 — Guard Before meta.call

Check map.has-key so optional plugin names fail safely.

SCSS
@use "sass:map";
@use "sass:meta";
@use "functions";

$fns: meta.module-functions("functions");
$name: "double";

.box {
  @if map.has-key($fns, $name) {
    width: meta.call(map.get($fns, $name), 24px);
  } @else {
    width: 24px;
  }
}

How It Works

  1. has-key confirms double exists.
  2. meta.call runs double(24px).
  3. Result is 48px.
  4. Missing names take the @else fallback.

Edge Cases & Pitfalls

Most module-functions bugs are wrong namespace strings or forgetting meta.call.

namespace

String must match @use

After @use "sass:math" as m, pass "m", not "math".

call

Map values need meta.call

You cannot use a function value like a normal CSS value without calling it.

guard

Check before optional calls

Use map.has-key (or function-exists) before map.get + call.

dart

Dart Sass only

Official docs: LibSass / Ruby Sass do not provide this API.

Toolchain

Sass Support

Prefer the module form with current Dart Sass.

APIStatus
meta.module-functions()Dart Sass only via @use "sass:meta"
Return typeMap (name → function value)
$moduleNamespace string or module value
LibSass / Ruby SassNot available

Compile with the Dart Sass CLI.

Remember

Key Takeaways

  • Returns a map of every function in a loaded module.
  • Call with map.get + meta.call (official pattern).
  • $module matches @use namespace in the current file.
  • Dart Sass only — great for registries and dynamic helpers.

One line: to list every function in a @use module, use meta.module-functions($module).

Practice

Compile Notes

Practical checklist:

checklist.txt
1. @use "sass:meta" (+ "sass:map")
2. @use "your-module"
3. $fns: meta.module-functions("your-module")
4. map.get / map.has-key / map.keys
5. meta.call($fn, $args...) to run a value

Frequently Asked Questions

meta.module-functions($module) returns a map of every function defined in that @use module—keys are function names, values are function values you can run with meta.call.
A string matching the namespace of a @use rule in the current file—for example "functions" after @use "functions", or "math" after @use "sass:math". It can also be a module value.
Official pattern: meta.call(map.get(meta.module-functions("functions"), "pow"), 3, 4). map.get picks the function value; meta.call runs it.
function-exists answers yes/no for one name. module-functions returns the whole catalog of functions in a module as a map.
get-function looks up one function by name. module-functions returns all functions in a module at once—handy for registries, loops, and map.has-key guards.
Dart Sass only (docs note since the module system / 1.23+ era). LibSass and Ruby Sass do not. Prefer current Dart Sass.

Next: Sass meta.module-mixins()

Get a map of all mixins from a loaded module.

meta.module-mixins() →

About the author

Mari Selvan M P
Mari Selvan M P 🔗

Developer, cloud engineer, and technical writer

  • Experience 12 years building web and cloud systems
  • Focus Full Stack Development, AWS, and Developer Education

I write practical tutorials so students and working developers can learn by doing—from databases and APIs to deployment on AWS.

AWS Certified Developer – Associate (Credly)

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Sass meta.mixin-exists Function Sass meta.module-mixins Function