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When novice programming students already know one programming language and have to learn another, what issues do they run into? We specifically focus on one or both languages being functional, varying along two axes: syntax and semantics. We report on problems, especially persistent ones. This work can be of immediate value to educators and also sets up avenues for future research.
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Qunity: A Unified Language for Quantum and Classical Computing
We introduce Qunity, a new quantum programming language designed to treat quantum computing as a natural generalization of classical computing. Qunity presents a unified syntax where familiar programming constructs can have both quantum and classical effects. For example, one can use sum types to implement the direct sum of linear operators, exception-handling syntax to implement projective measurements, and aliasing to induce entanglement. Further, Qunity takes advantage of the overlooked BQP subroutine theorem, allowing one to construct reversible subroutines from irreversible quantum algorithms through the uncomputation of garbage outputs. Unlike existing languages that enable quantum aspects with separate add-ons (like a classical language with quantum gates bolted on), Qunity provides a unified syntax and a novel denotational semantics that guarantees that programs are quantum mechanically valid. We present Qunity's syntax, type system, and denotational semantics, showing how it can cleanly express several quantum algorithms. We also detail how Qunity can be compiled into a low-level qubit circuit language like OpenQASM, proving the realizability of our design.
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- Award ID(s):
- 1730449
- PAR ID:
- 10602497
- Publisher / Repository:
- Association for Computing Machinery (ACM)
- Date Published:
- Journal Name:
- Proceedings of the ACM on Programming Languages
- Volume:
- 7
- Issue:
- POPL
- ISSN:
- 2475-1421
- Format(s):
- Medium: X Size: p. 921-951
- Size(s):
- p. 921-951
- Sponsoring Org:
- National Science Foundation
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