From HandWiki
Short description: Dialect of the Lisp programming language designed to interact with Python
Hy Cuddles.png
Hy logo - Cuddles the cuttlefish
ParadigmMulti-paradigm: procedural, functional, object-oriented, meta, reflective, generic
Designed byPaul Tagliamonte
DevelopersCore team
First appeared2013; 11 years ago (2013)
Preview release
1.0a4[1] / 16 March 2022; 23 months ago (2022-03-16)[1]
Scopelexical, optionally dynamic[citation needed]
PlatformIA-32, x86-64
Filename extensions.hy
Influenced by
Kawa, Clojure, Common Lisp

Hy is a dialect of the Lisp programming language designed to interact with Python by translating s-expressions into Python's abstract syntax tree (AST).[2][3] Hy was introduced at Python Conference (PyCon) 2013 by Paul Tagliamonte.[4] Lisp allows operating on code as data (metaprogramming), thus Hy can be used to write domain-specific languages.[5]

Similar to Kawa's and Clojure's mappings onto the Java virtual machine (JVM),[6][7] Hy is meant to operate as a transparent Lisp front-end for Python.[8] It allows Python libraries, including the standard library, to be imported and accessed alongside Hy code with a compiling[note 1] step where both languages are converted into Python's AST.[note 2][9][10][11]

Example code

From the language documentation:[12]

=> (print "Hy!")
=> (defn salutationsnm [name] (print (+ "Hy " name "!")))
=> (salutationsnm "YourName")
Hy YourName!

See also


  1. The term "compiled" may apply to expressing Hy code in Python's AST or converting that AST into bytecode, the latter being dependent on the specific Python interpreter used and not Hy.
  2. Hy is tested on Python 2.7, 3.4 through 3.6, and PyPy.


  1. 1.0 1.1 "Hy 1.0a4". GitHub. https://github.com/hylang/hy/tree/1.0a4. 
  2. Jaworski, Michał; Ziadé, Tarek (2019). Expert Python programming (Third ed.). Birmingham, U.K.: Packt Publishing. pp. 173. ISBN 978-1-78980-677-9. OCLC 1125343555. https://www.worldcat.org/oclc/1125343555. 
  3. Danjou, Julien (2018). Serious Python: black-belt advice on deployment, scalability, testing, and more. San Francisco, CA: No Starch Press. pp. 145–149. ISBN 9781593278793. OCLC 1057729260. 
  4. Tagliamonte, Paul (2 April 2013). PyCon lightning talk (Speech). Python Conference (PyCon). Santa Clara. Retrieved 2 September 2014.
  5. Tagliamonte, Paul (11 April 2014). Getting Hy on Python: How to implement a Lisp front-end to Python (Speech). PyCon. Montreal. Retrieved 2 September 2014.
  6. Turto, Tuukka (14 February 2014). "Programming Can Be Fun with Hy". Open Source For You. http://www.opensourceforu.com/2014/02/programming-can-fun-hy/. 
  7. Watson, Mark (2020). A Lisp Programmer Living in Python-Land: The Hy Programming Language. LeanBooks. https://markwatson.com/opencontent/hy-lisp-python.pdf. 
  8. Edge, Jake (30 April 2014). "Getting Hy on Python". https://lwn.net/Articles/596626/. 
  9. "Hy Documentation". http://docs.hylang.org/en/stable/tutorial.html#hy-is-a-lisp-flavored-python. 
  10. Danjou, Julien (26 March 2014). "The AST". The Hacker's Guide to Python. pp. 165–172. https://books.google.com/books?id=B6nhAwAAQBAJ&pg=PT171. 
  11. Kitchin, John (31 March 2016). "More on Hy and why I think it is a big deal". Carnegie Mellon University. http://kitchingroup.cheme.cmu.edu/blog/2016/03/31/More-on-Hy-and-why-I-think-it-is-a-big-deal/. 
  12. "Quickstart". 15 May 2018. http://docs.hylang.org/en/stable/quickstart.html. 

External links