Transient Typechecks are (Almost) Free

Abstract

Transient gradual typing imposes run-time type tests that typically cause a linear slowdown in programs' performance. This performance impact discourages the use of type annotations because adding types to a program makes the program slower. A virtual machine can employ standard justin-time optimizations to reduce the overhead of transient checks to near zero. These optimizations can give gradually-typed languages performance comparable to state-of-the-art dynamic languages, so programmers can add types to their code without affecting their programs' performance. ACM Subject ClassificationSoftware and its engineering → Just-in-time compilers; Software and its engineering → Object oriented languages; Software and its engineering → Interpreters