Open Source Haskell Software
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Haskell Software
Browse free open source Haskell Software and projects below. Use the toggles on the left to filter open source Haskell Software by OS, license, language, programming language, and project status.
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Pandoc
The universal markup converter
Pandoc is a universal document converter able to convert files from a multitude of markup formats into another. With Pandoc, you have a swiss-army knife of a converter, able to convert practically any markup format into any other. Pandoc contains a Haskell library for conversions as well as a command-line tool that uses this library. It can convert to and from just about anything-- lightweight markup formats, HTML formats, documentation formats, ebooks, TeX formats, word processor formats and so much more. It understands several useful markdown syntax extensions, such as document metadata, footnotes, tables, and more. If you want strict markdown compatibility however, these extensions can be turned off. Pandoc is no doubt powerful and customizable, but it is important to note that its intermediate representation of a document is less expressive than many of the formats, so it may not produce perfect conversions every time. -
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SimpleX
The first messaging platform operating without user identifiers
Other apps have user IDs: Signal, Matrix, Session, Briar, Jami, Cwtch, etc. SimpleX does not, not even random numbers. This radically improves your privacy. The video shows how you connect to your friend via their 1-time QR-code, in person or via a video link. You can also connect by sharing an invitation link. Temporary anonymous pairwise identifiers SimpleX uses temporary anonymous pairwise addresses and credentials for each user contact or group member. It allows to deliver messages without user profile identifiers, providing better meta-data privacy than alternatives. Many communication platforms are vulnerable to MITM attacks by servers or network providers. To prevent it SimpleX apps pass one-time keys out-of-band when you share an address as a link or a QR code. Double-ratchet protocol. OTR messaging with perfect forward secrecy and break-in recovery. NaCL cryptobox in each queue to prevent traffic correlation between message queues if TLS is compromised. -
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FOSSA CLI
Fast, portable and reliable dependency analysis for any codebase
FOSSA CLI is a command-line tool that scans your codebase to identify open-source dependencies and their associated licenses and vulnerabilities. It integrates into CI/CD pipelines to provide automated compliance checks, license audits, and security analysis. Designed for enterprise software teams, FOSSA CLI helps enforce open-source policies at scale and provides accurate, automated insights into third-party software usage through deep analysis of transitive dependencies and ecosystem-specific configurations. -
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PostgREST
REST API for any Postgres database
PostgREST is a standalone web server that turns your PostgreSQL database directly into a RESTful API. The structural constraints and permissions in the database determine the API endpoints and operations. Using PostgREST is an alternative to manual CRUD programming. Custom API servers suffer problems. Writing business logic often duplicates, ignores or hobbles database structure. Object-relational mapping is a leaky abstraction leading to slow imperative code. The PostgREST philosophy establishes a single declarative source of truth: the data itself. It’s easier to ask PostgreSQL to join data for you and let its query planner figure out the details than to loop through rows yourself. It’s easier to assign permissions to db objects than to add guards in controllers. (This is especially true for cascading permissions in data dependencies.) It’s easier to set constraints than to litter code with sanity checks. -
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nixfmt
The official formatter for Nix code
nixfmt is a code formatter for the Nix expression language, aiming to provide consistent and idiomatic formatting for Nix files. It is written in Haskell and designed to be fast, predictable, and fully automatic with zero configuration. nixfmt helps Nix developers maintain readability and code consistency across large codebases, facilitating collaboration and version control workflows. -
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Stack
The Haskell Tool Stack
Stack is a cross-platform build tool for Haskell projects that simplifies dependency management, project setup, and reproducible builds. It provides curated package sets (Stackage), isolated project environments, and consistent tooling for compiling and testing Haskell applications. Stack streamlines workflows for developers by automating many parts of the Haskell toolchain, making it easier to get started and maintain complex codebases. It supports integration with GHC (Glasgow Haskell Compiler) and Hackage. -
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Wasp
A programming language that understands what a web app is
Wasp (Web Application Specification Language) is a declarative DSL (domain-specific language) for developing, building and deploying modern full-stack web apps with less code. Concepts such as app, page, user, login, frontend, production, etc. are baked into the language, bringing a new level of expressiveness and allowing you to get more work done with fewer lines of code. While describing high-level features with Wasp, you still write the rest of your logic in your favorite technologies (currently React, NodeJS, Prisma). Wasp is in alpha and is therefore likely to change a lot, have bugs and miss important features. Due to its expressiveness, you can create and deploy a production-ready web app from scratch with very few lines of concise, consistent, declarative code. When you need more control than Wasp offers, you can write code in existing technologies such as js/html/css/... and combine it with Wasp code! -
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Clash
Haskell to VHDL/Verilog/SystemVerilog compiler
Clash is a functional hardware description language that borrows both its syntax and semantics from the functional programming language Haskell. It provides a familiar structural design approach to both combinational and synchronous sequential circuits. The Clash compiler transforms these high-level descriptions to low-level synthesizable VHDL, Verilog, or SystemVerilog. Clash is an open-source project, licensed under the permissive BSD2 license, and actively maintained by QBayLogic. The Clash project is a Haskell Foundation affiliated project. Clash is built on Haskell which provides an excellent foundation for well-typed code. Together with Clash's standard library it is easy to build scalable and reusable hardware designs. Load your designs in an interpreter and easily test all your component without needing to setup a test bench. Although Clash offers many features, you sometimes need to directly access VHDL, Verilog, or SystemVerilog directly. -
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Extism
The Universal Plug-in System. Extend anything with WebAssembly
Extism is a plug-in system for everyone. We've carefully designed it to be flexible, fitting into codebases of all shapes and sizes, but opinionated enough so that things Just Work™ the way they should. Extism's goal is to make all software programmable. You can use Extism in your codebase, regardless of the programming language. We support several environments through our official Host SDKs, and are adding more language support all the time. A plug-in system is software that enables your users or customers to add some logic into certain points in your application. You decide where this logic runs, and your users decide what the plug-in does. Many engineering teams face an ever-growing list of feature requests, often exceeding their bandwidth several times over. How can you ever keep up? Making your product extensible by its end-users is a great way to move some of those features outside the core, and empower customers to make your software more useful for them. -
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ShellCheck
A static analysis tool for shell scripts
ShellCheck is a GPLv3 tool that provides warnings and possible suggestions for bash/sh shell scripts. ShellCheck finds bugs in your shell scripts. You can cabal, apt, dnf, pkg or brew install it locally right now. ShellCheck highlights and clarifies typical beginner's syntax mistakes and issues that cause a shell to give a cryptic error message. It shows typical intermediate level semantic problems that cause a shell to behave in a abnormally and counter-intuitively. It can also discover ssubtle caveats, corner cases and pitfalls that may cause an user's working script to fail under probable future circumstances. ShellCheck.net is always synchronized to the latest git version, and is the simplest way to give ShellCheck a go. -
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Agda
Agda is a dependently typed programming language
Agda is a dependently typed, total functional programming language and interactive theorem prover based on Martin-Löf’s type theory. It allows expressing programs and proofs in the same language, using the Curry–Howard correspondence. It features interactive development via Emacs, Atom, or VS Code. Agda is a dependently typed functional programming language. It has inductive families, i.e., data types which depend on values, such as the type of vectors of a given length. It also has parametrised modules, mixfix operators, Unicode characters, and an interactive Emacs interface which can assist the programmer in writing the program. Agda is a proof assistant. It is an interactive system for writing and checking proofs. Agda is based on intuitionistic type theory, a foundational system for constructive mathematics developed by the Swedish logician Per Martin-Löf. It has many similarities with other proof assistants based on dependent types, such as Coq, Epigram, Matita and NuPRL. -
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Cryptol
Cryptol: The Language of Cryptography
Cryptol is a domain-specific language (DSL) for specifying and verifying cryptographic algorithms. Developed by Galois, Cryptol provides a high-level mathematical syntax for describing cryptographic primitives and enables formal verification of algorithm properties. It is used in academic, research, and defense sectors to validate correctness and security through symbolic execution and model checking, ensuring critical cryptographic code is free of design flaws. -
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Ormolu
A formatter for Haskell source code
Ormolu is a formatter for Haskell source code. Using GHC's own parser to avoid parsing problems caused by haskell-src-exts. Let some whitespace be programmable. The layout of the input influences the layout choices in the output. This means that the choices between single-line/multi-line layouts in certain situations are made by the user, not by an algorithm. This makes the implementation simpler and leaves some control to the user while still guaranteeing that the formatted code is stylistically consistent. Writing code in such a way so it's easy to modify and maintain. Implementing one “true” formatting style which admits no configuration. The formatting style aims to result in minimal diffs. Choose a style compatible with modern dialects of Haskell. As new Haskell extensions enter broad use, we may change the style to accommodate them. Idempotence: formatting already formatted code doesn't change it. -
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Plutus
The Plutus language implementation and tools
Plutus is the smart contract development framework for the Cardano blockchain, created using Haskell. It provides the core infrastructure for writing, testing, and deploying secure, deterministic smart contracts on the Cardano platform. Plutus includes a custom functional language (Plutus Core), a higher-level embedded DSL (Plutus Tx) for writing contracts in Haskell, and an off-chain infrastructure for managing interactions. It ensures strong correctness guarantees through formal verification and functional programming paradigms. -
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Reflex
Interactive programs without callbacks or side-effects
Reflex apps automatically react to changing data. This keeps every interaction current, accurately representing the relationship between your data and the real world. Reflex components are modular and reusable. If your requirements change, your app can quickly and easily be reworked. The modularity of Reflex lets you iterate quickly, without wasting code. Reflex has been built to seamlessly support interfaces on desktop, mobile, web, and other platforms, all in Haskell. Regardless of your platform needs, Reflex lets you take your team and your code with you. Reflex is the key to writing self-updating user interfaces. Develop efficiently no matter how many times you pivot. One team, one code base, every platform. You don’t have to choose between building quickly or sustainably anymore. Reflex-FRP allows you to write production quality code from the get-go, with less technical debt. -
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tetris
A terminal interface for Tetris
A terminal interface for Tetris. Installation on MacOS and Linux is outlined below. Windows support is questionable, but you can try to install from source. The default game is run by simply executing the tetris command. If the unicode characters look a bit wonky in your terminal, you can also run. People seem to have varying levels of success with the linux binary. Please note that it is compiled dynamically and hence should not be expected to work on most distros. This code is built on top of brick which makes building terminal user interfaces very accessible. -
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Kmonad
An advanced keyboard manager
KMonad is a cross-platform, advanced keyboard remapping tool written in Haskell. It provides low-level key control, supporting layers, tap-hold combos, multi-tap, macros, and more—even for keyboards without firmware-level customization. -
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PureScript
A strongly-typed language that compiles to JavaScript
Compile to readable JavaScript and reuse existing JavaScript code easily. An extensive collection of libraries for development of web applications, web servers, apps and more. Excellent tooling and editor support with instant rebuilds. An active community with many learning resources. Build real-world applications using functional techniques and expressive types, such as: Algebraic data types and pattern matching. Row polymorphism and extensible records. Higher kinded types and type classes with functional dependencies, as well as higher-rank polymorphism. Precompiled binaries are available for OSX, Linux, and Windows. The Pursuit package database hosts searchable documentation for PureScript packages. The recommended build tool for PureScript is Spago, which can be installed using npm. -
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SimpleXMQ
A reference implementation of the SimpleX Messaging Protocol
A reference implementation of the SimpleX Messaging Protocol for simplex queues over public networks. SimpleXMQ is a message broker for managing message queues and sending messages over a public network. It consists of an SMP server, SMP client library, and SMP agent that implements SMP protocol for client-server communication and SMP agent protocol to manage duplex connections via simplex queues on multiple SMP servers. SMP protocol is inspired by Redis serialization protocol, but it is much simpler - it currently has only 10 client commands and 8 server responses. -
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koka
Koka language compiler and interpreter
Koka is a strongly typed functional-style language with effect types and handlers. The core of Koka consists of a small set of well-studied language features, like first-class functions, a polymorphic type- and effect system, algebraic data types, and effect handlers. Each of these is composable and avoid the addition of “special” extensions by being as general as possible. Koka tracks the (side) effects of every function in its type, where pure and effectful computations are distinguished. The precise effect typing gives Koka rock-solid semantics backed by well-studied category theory, which makes Koka particularly easy to reason about for both humans and compilers. Effect handlers let you define advanced control abstractions, like exceptions, async/await, or probabilistic programs, as a user library in a typed and composable way. Perceus is an advanced compilation method for reference counting. -
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Cardano Node
The core component that is used to participate in a Cardano
Cardano Node is the core software that powers the Cardano blockchain, a decentralized, proof-of-stake platform for smart contracts and digital assets. Developed in Haskell, the node allows participation in Cardano’s network by validating transactions, producing blocks, and maintaining the ledger. It supports Shelley, Goguen, Basho, and other phases of Cardano’s roadmap, and plays a crucial role in network security and consensus. The node is configurable for different use cases, including running full nodes, relay nodes, or stake pool operators. -
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Hasktorch
Tensors and neural networks in Haskell
Hasktorch is a powerful Haskell library for tensor computation and neural network modeling, built on top of libtorch (the backend of PyTorch). It brings differentiable programming, automatic differentiation, and efficient tensor operations into Haskell’s strongly typed functional paradigm. This project is in active development, so expect changes to the library API as it evolves. We would like to invite new users to join our Hasktorch discord space for questions and discussions. Contributions/PR are encouraged. Hasktorch is a library for tensors and neural networks in Haskell. It is an independent open source community project which leverages the core C++ libraries shared by PyTorch. -
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Rome
Carthage cache for S3, Minio, Ceph, Google Storage, Artifactory, etc.
Carthage cache for S3, Minio, Ceph, Google Storage, Artifactory and many others. Rome is a tool that allows developers on Apple platforms to use Amazon's S3, Minio, Ceph, other S3-compatible object stores or/and a local folder. The Rome binary is also attached as a zip to each release on the releases page here on GitHub. Suppose you're working a number of frameworks for your project and want to share those with your team. A great way to do so is to use Carthage and have team members point the Cartfile to the new framework version (or branch, tag, commit) and run Carthage update. Unfortunately, this will require them to build from scratch a new framework. This is particularly annoying if the dependency tree for that framework is big and/or takes a long time to build. Use a cache. The first team member (or a CI) can build the framework and share it, while all other developers can get it from the cache with no waiting time. -
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pandoc-crossref filter
Pandoc filter for cross-references
pandoc-crossref is a pandoc filter for numbering figures, equations, tables and cross-references to them. The input file (like demo.md) can be converted into HTML, LaTeX, PDF, Markdown or other formats. Optionally, you can use cleveref for LaTeX/PDF output, e.g. cleveref PDF, cleveref LaTeX, and listings package, e.g. listings PDF, listings LaTeX. This package tries to use LaTeX labels and references if output type is LaTeX. It also tries to supplement rudimentary LaTeX configuration that should mimic metadata configuration by setting header-includes variable. The easiest option to get pandoc-crossref on Windows, macOS, or Linux, is to download pre-built executables available at the releases page. Bear in mind that those are a product of automated build scripts, and as such, provided as-is, with zero guarantees. Feel free to open issues if those don't work though, I'll try to do what I can.