Variable Interpolation

Basic Substitution

Use double curly braces to define variable placeholders:

You are a {{role}} assistant helping {{user_name}}.
Your task: {{task}}

Variable names must match [a-zA-Z_][a-zA-Z0-9_]*. Leading/trailing whitespace inside {{ }} is trimmed.

Conditional Blocks

Use {{#if variable}} to include content only when a variable is truthy:

Answer the following question.
{{#if context}}
Context: {{context}}
{{/if}}
Question: {{question}}

A value is truthy if it is non-null, non-empty, not false, and not an empty array.

Iteration Blocks

Use {{#each array}} to iterate over a list:

Analyze the following items:
{{#each items}}
- {{this}}
{{/each}}

For arrays of objects:

Here are the team members:
{{#each members}}
- {{name}} ({{role}})
{{/each}}

Rendering

TypeScript

import { PromptRenderer } from 'minions-prompts';

const renderer = new PromptRenderer();

const result = renderer.render(
  'Hello {{name}}, {{#if premium}}you have premium access.{{/if}}',
  { name: 'Alice', premium: true },
);
// → "Hello Alice, you have premium access."

Python

from minions_prompts import PromptRenderer

renderer = PromptRenderer()

result = renderer.render(
    "Hello {{name}}, {{#if premium}}you have premium access.{{/if}}",
    {"name": "Alice", "premium": True},
)
# → "Hello Alice, you have premium access."

Required Variables

Mark variables as required to get clear errors when they are missing:

TypeScript

renderer.render(template, variables, {
  requiredVariables: ['topic', 'audience'],
});
// Throws RendererError if topic or audience are missing

Python

renderer.render(template, variables, required_variables=["topic", "audience"])
# Raises RendererError if topic or audience are missing