silt VS CompCert

Compare silt vs CompCert and see what are their differences.


An in-progress fast, dependently typed, functional programming language implemented in Swift. (by silt-lang)


The CompCert formally-verified C compiler (by AbsInt)
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silt CompCert
1 36
238 1,729
0.4% 1.6%
0.0 6.8
over 4 years ago 11 days ago
Swift Coq
MIT License GNU General Public License v3.0 or later
The number of mentions indicates the total number of mentions that we've tracked plus the number of user suggested alternatives.
Stars - the number of stars that a project has on GitHub. Growth - month over month growth in stars.
Activity is a relative number indicating how actively a project is being developed. Recent commits have higher weight than older ones.
For example, an activity of 9.0 indicates that a project is amongst the top 10% of the most actively developed projects that we are tracking.


Posts with mentions or reviews of silt. We have used some of these posts to build our list of alternatives and similar projects. The last one was on 2021-02-17.
  • Phantom types in Swift
    2 projects | /r/swift | 17 Feb 2021
    This is absolutely one of my favorite patterns. I really like using it to build state machines. Each state has a constrained extension full of behaviors and a method you can use to transit to the next state that just scoops all the data into a new container with a different tag. A light extension of that pattern is to then use associated/nested types dependent on the tags to define other behaviors such as custom state associated with each point in the machine. Conversely, behaviors common to every state can be added via an extension as per usual. Here’s a big hairy TypeChecker written following this pattern with its implementation split across an entire modules’ worth of files. Each transition point from elaboration to type checking to type inference is neatly contained by the tag which uniquely determines the state carried at each point.


Posts with mentions or reviews of CompCert. We have used some of these posts to build our list of alternatives and similar projects. The last one was on 2024-01-31.
  • Differ: Tool for testing and validating transformed programs
    6 projects | | 31 Jan 2024
    A big problem is that proving that transformations preserve semantics is very hard. Formal methods has huge potential and I believe it will be a big part of the future, but it hasn't become mainstream yet. Probably a big reason why is that right now it's simply not practical: the things you can prove are much more limited than the things you can do, and it's a lot less work to just create a large testsuite.

    Example: CompCert (, a formally-verified compiler AKA formally-verified sequence of semantics-preserving transformations from C code to Assembly. It's a great accomplishment, but few people are actually compiling their code with CompCert. Because GCC and LLVM are much faster[1], and have been used so widely that >99.9% of code is going to be compiled correctly, especially code which isn't doing anything extremely weird.

    But as articles like this show, no matter how large a testsuite there may always be bugs, tests will never provide the kind of guarantees formal verification does.

    [1] From CompCert, "Performance of the generated code is decent but not outstanding: on PowerPC, about 90% of the performance of GCC version 4 at optimization level 1"

  • So you think you know C?
    2 projects | | 20 Jan 2024
  • Can the language of proof assistants be used for general purpose programming?
    3 projects | | 27 Oct 2023
    Also a C compiler ( I did exaggerate bit in saying that anything non-trivial is "nearly impossible".

    However, both CompCert and sel4 took a few years to develop, whereas it would only take months if not weeks to make versions of both which aren't formally verified but heavily tested.

  • A Guide to Undefined Behavior in C and C++
    9 projects | | 17 Aug 2023
    From my experience, while many MCUs have settled for the big compilers (GCC and Clang), DSPs and some FPGAs (not Intel and Xilinx, those have lately settled for Clang and a combination of Clang and GCC respectively) use some pretty bespoke compilers (just running ./ --version is enough to verify this, if the compiler even offers that option). That's not necessarily bad, since many of them offer some really useful features, but error messages can be really cryptic in some cases. Also some industries require use of verified compilers, like CompCert[1], and in such cases GCC and Clang just don't cut it.


  • Rosenpass – formally verified post-quantum WireGuard
    9 projects | | 28 Feb 2023
  • OpenAI might be training its AI technology to replace some software engineers, report says
    4 projects | /r/programming | 28 Jan 2023
    But that's fine, because we can do even better with things like the CompCert C compiler, which is formally proven to produce correct asm output for ISO C 2011 source. It's designed for high-reliability, safety-critical applications; it's used for things like Airbus A380 avionics software, or control software for emergency generators at nuclear power plants. Software that's probably not overly sophisticated and doesn't need to be highly optimized, but does need to work ~100% correctly, ~100% of the time.
  • Checked C
    14 projects | | 21 Dec 2022
    Does anybody know how does this compare to ?
  • Is it possible to make C as safe as Rust?
    3 projects | /r/C_Programming | 29 Sep 2022
    There is. They're called formally verified compilers, and are used for safety critical applications:
  • New Coq tutorial
    3 projects | /r/ProgrammingLanguages | 5 Jul 2022
    Hi all, Coq is a "proof assistant" that allows you to write both code and proofs in the same language (thanks to the Curry–Howard correspondence). Its uses range from pure math (e.g., the Feit–Thompson theorem was proven in Coq!) to reasoning about programming languages (e.g., proving the soundness of a type system) to writing verified code (e.g., this verified C compiler!). You can "extract" your code (without the proofs) to OCaml/Haskell/Scheme for running it in production. Coq is awesome, but it's known for having a steep learning curve (it's based on type theory, which is a foundational system of mathematics). It took me several years to become proficient in it. I wanted to help people pick it up faster than I did, so I wrote this introductory tutorial. Hope you find it useful!
  • The Software Foundations: mathematical underpinnings of reliable software
    4 projects | | 5 Mar 2022
    Not an expert but I've heard formal methods are used in Chip Design. Also a c compiler which uses formal verifcation. I tiored some exercises in the series. Its pretty interesting thing to do, but yes I don't think its great for rapid software development.

What are some alternatives?

When comparing silt and CompCert you can also consider the following projects:

coq - Coq is a formal proof management system. It provides a formal language to write mathematical definitions, executable algorithms and theorems together with an environment for semi-interactive development of machine-checked proofs.

seL4 - The seL4 microkernel

unbound - Replib: generic programming & Unbound: generic treatment of binders


vericert - A formally verified high-level synthesis tool based on CompCert and written in Coq.

koika - A core language for rule-based hardware design 🦑

corn - Coq Repository at Nijmegen [maintainers=@spitters,@VincentSe]

winix - A UNIX-style Operating System for the Waikato RISC Architecture Microprocessor (WRAMP)

proofs - My personal repository of formally verified mathematics.

cakeml - CakeML: A Verified Implementation of ML

wuffs - Wrangling Untrusted File Formats Safely

why3 - SPARK 2014 repository for the Why3 verification platform.