Sass meta.module-mixins() Function

What You’ll Learn

meta.module-mixins() belongs to the built-in sass:meta module. It returns every mixin in a @used module as a map of names to mixin values. This page covers the official stretch + meta.apply pattern, safe map.has-key guards, and five compiled examples.

What Is meta.module-mixins()?

Official docs: returns all the mixins defined in a module, as a map from mixin names to mixin values. Think of it as opening a style toolkit and seeing every recipe labeled by name—ready to pick one with map.get and include it with meta.apply.

• $module must be a string matching a @use namespace in the current file.
• Map keys are mixin names (strings). Map values are mixin values (not CSS yet).
• Pair with meta.apply to emit CSS (and forward @content).
• Dart Sass 1.69+ only—LibSass and Ruby Sass do not support it.

📝 Syntax

@use "sass:meta";

// Dart Sass 1.69+ (no legacy global name)
meta.module-mixins($module)

Parameters

Return value

📦 Loading sass:meta

@use "sass:map";
@use "sass:meta";
@use "mixins";

$mx: meta.module-mixins("mixins");

.header {
  @include meta.apply(map.get($mx, "stretch"));
}

There is no legacy global module-mixins(). Always load sass:meta and call meta.module-mixins.

⚙ The Official Apply Pattern

Docs show listing a custom mixins module, then picking one mixin and including it:

@use "sass:map";
@use "sass:meta";
@use "mixins";

// Map of names → mixin values
@debug meta.module-mixins("mixins");
// ("stretch": get-mixin("stretch"), …)

.header {
  @include meta.apply(map.get(meta.module-mixins("mixins"), "stretch"));
}

If you wrote @use "mixins" as mx, pass "mx" as $module.

📋 Related Meta Helpers

🛠 Compatibility

This is about Sass compilers, not browsers. The map is built at compile time.

Prefer current Dart Sass. meta.apply / meta.get-mixin share the same 1.69+ requirement.

Examples Gallery

Each example uses meta.module-mixins at compile time (Dart Sass 1.69+). Open View Compiled CSS for verified output.

@mixin stretch() {
  align-items: stretch;
  display: flex;
  flex-direction: row;
}

@mixin soft-shadow {
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.12);
}

@use "sass:map";
@use "sass:meta";
@use "mixins";

$mx: meta.module-mixins("mixins");

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

.probe {
  --keys: "stretch", "soft-shadow";
}

@use "sass:map";
@use "sass:meta";
@use "mixins";

.header {
  @include meta.apply(map.get(meta.module-mixins("mixins"), "stretch"));
}

.header {
  align-items: stretch;
  display: flex;
  flex-direction: row;
}

@use "sass:list";
@use "sass:map";
@use "sass:meta";
@use "mixins";

$mx: meta.module-mixins("mixins");

.count {
  --n: #{list.length(map.keys($mx))};
  --has-stretch: #{map.has-key($mx, "stretch")};
  --has-nope: #{map.has-key($mx, "nope")};
}

.count {
  --n: 2;
  --has-stretch: true;
  --has-nope: false;
}

@use "sass:map";
@use "sass:meta";
@use "mixins";

$mx: meta.module-mixins("mixins");

.card {
  @if map.has-key($mx, "soft-shadow") {
    @include meta.apply(map.get($mx, "soft-shadow"));
  }
  padding: 1rem;
}

.card {
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.12);
  padding: 1rem;
}

@use "sass:map";
@use "sass:meta";
@use "mixins";

$mx: meta.module-mixins("mixins");
$name: "stretch";

.row {
  @if map.has-key($mx, $name) {
    @include meta.apply(map.get($mx, $name));
  } @else {
    display: block;
  }
}

.row {
  align-items: stretch;
  display: flex;
  flex-direction: row;
}

🚀 Real-World Use Cases

• Theme / plugin registries — discover mixins a module exports, then include by name.
• Layout toolkits — pick stretch, center, or similar helpers from a catalog.
• Documentation / debug peeks — print map.keys while building a design system.
• Safe optional APIs — map.has-key before meta.apply.
• Module inventories — count or loop members for code generation at compile time.

⚠️ Common Pitfalls

• Wrong namespace string — must match this file’s @use … as name exactly.
• Module not loaded here — only @use rules in the current file count.
• Confusing values with CSS — map values are mixin references until you meta.apply them.
• Including without meta.apply — you cannot @include a map value directly; use meta.apply.
• Older Dart Sass — needs 1.69+ (same family as get-mixin / apply).

💡 Best Practices