higher-order-abstract-syntax

Implement Higher-Order Abstract Syntax encodings with capture-avoiding substitution.

17|2|Updated Feb 16, 2026
One-click install
npx skills add https://github.com/rainoftime/pl-skills --skill higher-order-abstract-syntax
Or copy as Structured Prompt for Agent
Please help me install this Agent Skill.
Skill: higher-order-abstract-syntax
Source: https://github.com/rainoftime/pl-skills/tree/main/higher-order-abstract-syntax
Command: npx skills add https://github.com/rainoftime/pl-skills --skill higher-order-abstract-syntax

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes references (resource) components.

What problem does it solve?

This Skill provides expertise in representing and manipulating syntax with embedded binders, crucial for building complex language structures and formal systems.

Core Features & Use Cases

  • HOAS Implementation: Design and implement Higher-Order Abstract Syntax encodings.
  • Binder Representation: Handle α-conversion, capture-avoiding substitution, and fresh name generation.
  • Use Case: Developing a proof assistant where terms have bound variables, ensuring correct substitution and equivalence checking.

Quick Start

Implement capture-avoiding substitution for a given HOAS term.

Frequently Asked Questions about higher-order-abstract-syntax

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
What is higher-order abstract syntax used for in formal methods?

Higher-order abstract syntax (HOAS) is used to represent and manipulate syntax with embedded binders, delegating variable binding to the host language to handle alpha-conversion and substitution automatically.

How do I implement capture-avoiding substitution for bound variables?

Capture-avoiding substitution for bound variables is implemented by using HOAS encodings, which leverage the host functional language's native binding mechanisms to prevent variable capture during term manipulation.

Does higher-order abstract syntax work with embedded DSLs and proof assistants?

Yes, higher-order abstract syntax works with embedded DSLs and proof assistants by providing a structured way to represent complex language terms, ensuring correct equivalence checking and binder manipulation.

What is the best way to represent binders compared to nominal techniques?

Representing binders via HOAS uses the host language's lambda abstraction to manage binding, whereas nominal techniques rely on explicit fresh name generation and manual scope management.

Do I need to understand type theory to use higher-order abstract syntax?

Yes, understanding type theory and functional programming is required to use higher-order abstract syntax, as the technique relies heavily on host language type systems to encode and manipulate syntax correctly.

When should I not use higher-order abstract syntax for metaprogramming?

You should avoid higher-order abstract syntax for metaprogramming when your host language lacks strong functional programming support or when you need explicit control over fresh name generation and nominal techniques.