dafny
WeasyPrint
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dafny | WeasyPrint | |
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31 | 43 | |
2,665 | 6,635 | |
1.5% | 2.5% | |
9.7 | 9.4 | |
4 days ago | 6 days ago | |
C# | Python | |
GNU General Public License v3.0 or later | BSD 3-clause "New" or "Revised" License |
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dafny
- Dafny is a verification-aware programming language
- Candy – a minimalistic functional programming language
- Dafny – a verification-aware programming language
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Lean4 helped Terence Tao discover a small bug in his recent paper
Code correctness is a lost art. I requirement to think in abstractions is what scares a lot of devs to avoid it. The higher abstraction language (formal specs) focus on a dedicated language to describe code, whereas lower abstractions (code contracts) basically replace validation logic with a better model.
C# once had Code Contracts[1]; a simple yet powerful way to make formal specifications. The contracts was checked at compile time using the Z3 SMT solver[2]. It was unfortunately deprecated after a few years[3] and once removed from the .NET Runtime it was declared dead.
The closest thing C# now have is probably Dafny[4] while the C# dev guys still try to figure out how to implement it directly in the language[5].
[1] https://www.microsoft.com/en-us/research/project/code-contra...
[2] https://github.com/Z3Prover/z3
[3] https://github.com/microsoft/CodeContracts
[4] https://github.com/dafny-lang/dafny
[5] https://github.com/dotnet/csharplang/issues/105
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The Deep Link Equating Math Proofs and Computer Programs
I don't think something that specific exists. There are a very large number of formal methods tools, each with different specialties / domains.
For verification with proof assistants, [Software Foundations](https://softwarefoundations.cis.upenn.edu/) and [Concrete Semantics](http://concrete-semantics.org/) are both solid.
For verification via model checking, you can check out [Learn TLA+](https://learntla.com/), and the more theoretical [Specifying Systems](https://lamport.azurewebsites.net/tla/book-02-08-08.pdf).
For more theory, check out [Formal Reasoning About Programs](http://adam.chlipala.net/frap/).
And for general projects look at [F*](https://www.fstar-lang.org/) and [Dafny](https://dafny.org/).
- Dafny
- The Dafny Programming and Verification Language
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In Which I Claim Rich Hickey Is Wrong
Dafny and Whiley are two examples with explicit verification support. Idris and other dependently typed languages should all be rich enough to express the required predicate but might not necessarily be able to accept a reasonable implementation as proof. Isabelle, Lean, Coq, and other theorem provers definitely can express the capability but aren't going to churn out much in the way of executable programs; they're more useful to guide an implementation in a more practical functional language but then the proof is separated from the implementation, and you could also use tools like TLA+.
https://dafny.org/
https://whiley.org/
https://www.idris-lang.org/
https://isabelle.in.tum.de/
https://leanprover.github.io/
https://coq.inria.fr/
http://lamport.azurewebsites.net/tla/tla.html
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Programming Languages Going Above and Beyond
> I think we can assume it won't be as efficient has hand written code
Actually, surprisingly, not necessarily the case!
If you'll refer to the discussion in https://github.com/dafny-lang/dafny/issues/601 and in https://github.com/dafny-lang/dafny/issues/547, Dafny can statically prove that certain compiler branches are not possible and will never be taken (such as out-of-bounds on index access, logical assumptions about whether a value is greater than or less than some other value, etc). This lets you code in the assumptions (__assume in C++ or unreachable_unchecked() under rust) that will allow the compiler to optimize the codegen using this information.
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What are the current hot topics in type theory and static analysis?
Most of the proof assistants out there: Lean, Coq, Dafny, Isabelle, F*, Idris 2, and Agda. And the main concepts are dependent types, Homotopy Type Theory AKA HoTT, and Category Theory. Warning: HoTT and Category Theory are really dense, you're going to really need to research them.
WeasyPrint
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Launch HN: Onedoc (YC W24) – A better way to create PDFs
Is there a reason you didn't consider something like Weasyprint?
https://weasyprint.org
I've gone through a number of systems to convert CV's, business cards, and other docs and it hasn't let me down yet.
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CSS for Printing to Paper
You don't _have_ to use a browser. I had very good results with Weasyprint [0]. And there's also PrinceXML [1] if you're willing to pay.
[0]: https://weasyprint.org/
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Show HN: A new open-source library to design PDF using React
Thanks for your answer! I imagined you would be using PrinceXML behind the scenes since that is probably the gold standard in HTML+CSS rendering.
The only open source alternative I know of is WeasyPrint at https://weasyprint.org/. I'm not sure how well it fares against PrinceXML, though.
And thanks for the pointer to Taffy - I didn't know it before!
- 1.5M PDFs in 25 Minutes
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Htmldocs: Typeset and Generate PDFs with HTML/CSS
Flexbox support has been [included][1] since 2018, although my use case was the prototypical one - a single row w/ 3 columns - so YMMV with how it handles more complex layouts.
[1]: https://github.com/Kozea/WeasyPrint/pull/579
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How to Simply Generate a PDF From HTML in Symfony With WeasyPrint
Performance is not the strength of WeasyPrint, meaning that heavy HTML files will increase generation time. You should always compress images before attaching them, as they are not compressed by default. Generating a 50-page-long PDF may take up to a minute in extreme cases, although multi-page documents generated on my project take fewer than 2 seconds to generate.
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Show HN: Invoice Dragon – An Open Source App to Create PDF Invoices for Free
For Python there is Weasyprint: you prepare the invoice as an HTML document, and Weasyprint turns it into a PDF
https://weasyprint.org/
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The Gemini protocol seen by this HTTP client person (curl dev)
Well yes, but you can implement HTML+CSS. WeasyPrint did from scratch, and independent implementations of HTML+CSS are considerably more numerous than HTML+CSS+JS.
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Library to convert HTML to pdf in Golang
In a recent project I used https://github.com/Kozea/WeasyPrint/ it is written in python, so you will need to use it like so:
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RE: If you had to pick a library from another language (Rust, JS, etc.) that isn’t currently available in Python and have it instantly converted into Python for you to use, what would it be?
You should maybe check out weasyprint. https://weasyprint.org/
What are some alternatives?
tlaplus - TLC is a model checker for specifications written in TLA+. The TLA+Toolbox is an IDE for TLA+.
ReportLab
FStar - A Proof-oriented Programming Language
PyPDF2 - A pure-python PDF library capable of splitting, merging, cropping, and transforming the pages of PDF files
rust - Rust for the xtensa architecture. Built in targets for the ESP32 and ESP8266
WKHTMLToPDF - Convert HTML to PDF using Webkit (QtWebKit)
koka - Koka language compiler and interpreter
QuestPDF - QuestPDF is a modern open-source .NET library for PDF document generation. Offering comprehensive layout engine powered by concise and discoverable C# Fluent API. Easily generate PDF reports, invoices, exports, etc.
Rust-for-Linux - Adding support for the Rust language to the Linux kernel.
PDFMiner - Python PDF Parser (Not actively maintained). Check out pdfminer.six.
interactive - .NET Interactive combines the power of .NET with many other languages to create notebooks, REPLs, and embedded coding experiences. Share code, explore data, write, and learn across your apps in ways you couldn't before.
MathJax - Beautiful and accessible math in all browsers