dynpr

dynpr is a lightweight Ruby CLI tool for rendering dynamic text templates with double curly braces ({{ }}) used as placeholders. It was originally designed to streamline the process of generating prompts for large language models (LLMs), making it easy to build and manage a local library of reusable prompt templates.

With dynpr, you can define your LLM prompts as templates and inject arguments on the fly from the command line — perfect for quickly generating personalized or context-specific prompts from a central directory.

Templates can include required variables like {{user}} or optional ones with defaults like {{env:development}}. The script expects a single positional argument (assigned to INPUT), while all other variables are passed as keyword arguments using the -key value format.

Before using dynpr, make sure to set the DYNPR_TEMPLATE_DIR environment variable to point to your template folder. Template files are resolved relative to this directory.

The tool checks for missing required variables and reports redundant ones, ensuring your input always matches the structure of the template.

Example

dynpr welcome.txt "John Doe" -user Alice -env production

This will render the welcome.txt template using the provided values, substituting the variables accordingly.

Use Cases

One of the most compelling use cases for dynprompt is its seamless integration with Simon Willison's excellent LLM command-line tool. By combining dynprompt with llm, you can dynamically generate prompts and immediately process them through your preferred large language model.

For example, to generate an essay prompt on "Climate change" and process it with your configured LLM:

dynpr write_essay 'Climate change' | llm

This pipeline allows you to effortlessly create structured prompts and obtain responses from your LLM of choice, streamlining tasks such as content generation, code explanation, or data analysis, etc.

Installation

Use the included deploy.sh script to install dynpr into your local bin directory:

./deploy.sh

Make sure to define your template directory in your shell configuration:

export DYNPR_TEMPLATE_DIR=~/my-templates

Template Example

A simple template file might look like this:

Hello, {{user}}!
Running in {{env:development}} environment.
Input provided: {{INPUT}}

If no value is passed for env, the default "development" will be used.

Zsh Tab Completion

Also add this to your .zshrc to enable TAB-completion of files from both the current working directory and the template directory (DYNPR_TEMPLATE_DIR):

export DYNPR_TEMPLATE_DIR='<path_to_prompts_dir>'

_dynpr_completion() {
    local template_dir="${DYNPR_TEMPLATE_DIR}"
    local expl

    # Add current dir
    _files

    # Add template dir as alternate search path
    if [[ -d "$template_dir" ]]; then
        _path_files -W "$template_dir"
    fi
}
# Completion from both template dir and current dir for dynpr tool
compdef _dynpr_completion dynpr

After adding this, restart your terminal or run source ~/.zshrc to activate it.

Requirements

dynpr uses only built-in Ruby libraries and requires no external gems or dependencies.