Research interests

Programming languages are the "ultimate abstraction" and yet, programmers can't deploy them as easily as other abstraction mechanisms, e.g., functions or objects, because of a lack of support from existing languages.

My research aims to close this gap by creating a general-purpose "language-oriented" language.

My recent work focuses on type systems. It enables easily creating new typed languages that are fully-featured, possibly domain-specific, yet flexible enough to be extended and improved just as easily. In particular, the languages are macro-extensible, so advanced typed system features like pattern matching, GADTs, and even type classes can be added as user-level libraries.

Previously, my dissertation explored lazy evaluation from both a theoretical and a practical perspective.

I also enjoy hacking with/on Racket.

Research Group

Current

• Chantelle Boateng (Sloan IDS Fellow)

Previous

• Leif Andersen (post-doc)

• Kyle Clapper (PhD) (Jabra)

• Mitch Gamburg (NEU ugrad) (Meta)

• Daniel Melcer (NEU ugrad) (NEU PhD)

• Milo Turner (NEU ugrad) (Starry Internet)

• Alex Knauth (NEU ugrad) (Mutual Knowledge Systems)

• Vishesh Yadav (NEU masters) (Apple)

Papers

Type Tailoring (ECOOP 2024).
Ashton Wiersdorf, Stephen Chang, Matthias Felleisen, Ben Greenman.
[  pdf  | DROPS link  | blog  | code  ]

ProofViz: An Interactive Visual Proof Explorer (TFP 2021).
Daniel Melcer, Stephen Chang.
[  pdf  | ACM link  | Springer link  | abstract  | code  | talk  ]

Dependent Type Systems as Macros (POPL 2020).
Stephen Chang, Michael Ballantyne, Milo Turner, William J. Bowman.
[  pdf  | ACM link  | abstract  | code (Turnstile+)  | code (Cur)  | artifact  | slides  ]

Symbolic Types for Lenient Symbolic Execution (POPL 2018).
Stephen Chang, Alex Knauth, and Emina Torlak.
[  pdf  | abstract  | code repo  | artifact instructions, VirtualBox image (2.2GB)  ]

Super 8 Languages for Making Movies (Functional Pearl) (ICFP 2017).
Leif Andersen, Stephen Chang, and Matthias Felleisen.
[  pdf  ]

Type Systems as Macros (POPL 2017).
Stephen Chang, Alex Knauth, and Ben Greenman.
[  pdf  | abstract  | code repo  | artifact instructions, VirtualBox image (2.1GB)  ]

Profiling For Laziness (POPL 2014).
Stephen Chang and Matthias Felleisen.
[  pdf  | abstract  ]

Laziness By Need (ESOP 2013).
Stephen Chang.
[  pdf  | abstract  | slides  ]

The Call-by-need Lambda Calculus, Revisited (ESOP 2012).
Stephen Chang and Matthias Felleisen.
[  pdf  | abstract  | slides  | arXiv  ]

From Stack Traces to Lazy Rewriting Sequences (IFL 2011).
Stephen Chang, Eli Barzilay, John Clements, and Matthias Felleisen.
[  pdf  | abstract  | slides  | arXiv (previous version)  ]

Evaluating Call By Need on the Control Stack (TFP 2010) (best student paper).
Stephen Chang, David Van Horn, and Matthias Felleisen.
[  pdf  | abstract  | slides  | arXiv  ]