The relevant conversation on twitter is Everything in the static type system is in the runtime too.
#STATIC CHECKER IN COMPILER DESIGN HOW TO#
This opens the door for exciting extensions to Swift’s type system in future. Run Time Type Checking in Swift At some point, when learning how to use Swift’s type system, it is important to understand that Swift (like many other languages) has two different forms of type checking: static and dynamic.
![static checker in compiler design static checker in compiler design](https://image.slidesharecdn.com/lecture14-15-160802160657/95/type-checkingcompiler-design-sharethisifyoulike-6-638.jpg)
A static checker reads a program, analyses it and attempts to discover potential bugs with out running the program. The twitter conversation also revealed that all compile time information is available at runtime, too. 12 What are a Pretty Printer and Static Checker A Pretty printer analyses a program and prints it in such a way that the structure of the program becomes clearly visible.
![static checker in compiler design static checker in compiler design](https://cdn.searchenginejournal.com/wp-content/uploads/2021/04/yoast-6080a166f2310-680x488.png)
Russ Bishop (in the comments) and Joe Groff (on twitter) pointed out that the idea presented in this post is already being discussed as part of extending Swift’s support for generics. If you have corrections or general thoughts on this post, I would love to hear from you. I cannot finish this post without a fabulous quote from type checking and compile-time generics are like steak and ice-cream – both are nice but mixing them is a bit weird. This means the information about generic constraints is still available at run time and, at least in theory, the idea of dynamically created constrained metatypes might be possible.įor now it is helpful to understand the limitations of mixing static and dynamic type checking and to be aware of the possible workarounds. However, according to this Stack Overflow answer by David Smith, Swift currently checks generic constraints at run time (unless the compiler generates specialized copies of a function for performance optimizations). I would assume that the relative cost of implementing this is huge, compared to the benefits it would provide to a very small part of the average Swift codebase. Pascal Static versus Dynamic Checking Static checking: the compiler enforces programming language’s static semantics. In compiler design, static single assignment form (often abbreviated as SSA form or simply SSA) is a property of an intermediate representation (IR), which requires that each variable be assigned exactly once, and every variable be defined before it is used.
#STATIC CHECKER IN COMPILER DESIGN CODE#
Position of type checker Some compilers combine type checking (or checker) and Intermediate Code (IC) Generation with Parsing e.g.
![static checker in compiler design static checker in compiler design](https://import.viva64.com/docx/blog/0706_ML_in_Static_Analysis/image1.png)
I know too little about the Swift compiler to know if this is feasible at all. Static checking ensures that certain kind of errors will be detected and reported.