一句话：提出 Quick Look 设计，在 GHC 中实现非直谓类型推断，使多态类型成为一等公民，且改动局部且兼容现有扩展。
参数多态的类型推断极为成功，但长期存在一个尴尬缺陷：多态类型本身不是一等公民，即无法直接作为参数传递或出现在类型参数位置，这被称为 impredicativity。本文提出 Quick Look，一种实用、已实现且可部署的非直谓类型推断设计。为验证该设计，作者修改了生产级 Haskell 编译器 GHC，使其支持非直谓性。所需改动适度、局部化，并且与 GHC 众多其他类型系统扩展完全兼容。该工作表明，在实际编译器中实现 impredicative 类型推断是可行的，为 Haskell 及类似语言提供了更强的表达力。
Type inference for parametric polymorphism is wildly successful, but has always suffered from an embarrassing flaw: polymorphic types are themselves not first class. We present Quick Look, a practical, implemented, and deployable design for impredicative type inference. To demonstrate our claims, we have modified GHC, a production-quality Haskell compiler, to support impredicativity. The changes required are modest, localised, and are fully compatible with GHC's myriad other type system extensions.
@article{SerranoHJV20,
title = {A quick look at impredicativity},
author = {Alejandro Serrano and Jurriaan Hage and Simon Peyton Jones and Dimitrios Vytiniotis},
journal = {Proceedings of the ACM on Programming Languages},
volume = {4},
number = {ICFP},
year = {2020},
doi = {10.1145/3408971}
}