Duck Typing in Rust

What is Duck Typing?

Duck Typing describes the philosophy of the quote "If it looks like a duck and it quacks like a duck, then it probably is a duck." In Python, despite the prevalence of this philosophical abstraction, I really never used Duck Typing much at all. Whenever I thought I would find a use for it, there would be some small blemish on the Duck API that broke the build. The only time I really found a use for it was during monkey-patching or some other fairly abusive maneuver. In Rust, by comparison, each duck is accompanied by a contract that it at least behaves like a duck in some minimal fashion. This is incredibly useful, and is the underlying philosophy behind Rust's trait system.

What is Duck Typing in Rust?

A trait, much like a duck API, describes a number of methods and attributes on a type. At compile time these traits are attached to each concrete type and then any implementors are permitted to pass around trait objects in place of concrete types. In Practice, these ducks are everywhere, even in the standard library. Duck-typing is in-fact very practical, however it really really helps to be able to enforce things like whether to implement a .len() method or a .length() method or a .size() method. In Python those were the simple things that would break the duck API. Usually just even small spelling differences would turn a duck into a Tanager. I guess that I'm just glad to be on this side of the fence now.

trait ADuck {
   fn length(&self) -> usize;
}

Andrew Johnson

Open Source:

• Github

Other Platforms

• Medium

Published Books:

• Hands on Functional Programming in Rust
• LSTS Tutorial

Books that I am reading:

• E's
• Combinatorial Optimization
• Categories for the Working Mathematician

Top Referrers:

1. Google Search
2. DuckDuckGo Search
3. Sogou Search
4. Bing Search
5. Baidu Search

Tools:

• Perplexity 😵 Modelling Language
• A Categorical view of Typed Lambda Calculus with flexible Soundness Guarantees
• JLPT Flash Cards

Weblog:

• Static Site Generation with RDXL Web Templates
• An Attempt at Generative Programming in Rust
• Building Phonetic Autocorrection in Rust
• Finite State Transducers String-to-String Map in Rust
• Generating an RSS Feed for a site written in RDXL
• Using Into to Elegantly Coerce str and String types in Rust
• What is a cargo lockfile?
• Rust Sized, ?Sized, and unsized
• Duck Typing in Rust
• Run Rust on AWS Lambda
• Adding Support for CJK Characters
• Partial Differentiation Gradient Cheatsheet
• Rust, shared: by reference
• Rust, typed: associated types
• Rust, shared: by Sync
• Rust, abstracted: specialization
• Rust, asynchronized: threads
• LSTS: Term Type Pattern Matching