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Quivers

A typed functional probabilistic programming language with a PyTorch runtime.

CI Docs PyPI Python 3.14+ License: MIT

Tutorial · Examples · Language reference · Python API


Quivers is a typed probabilistic programming language for compositional models. A QVR source file is parsed, checked, and lowered to one intermediate representation used by the PyTorch runtime, editor tooling, and transpilers. The Python API provides variational and Monte Carlo inference, while the compiler emits models for eleven probabilistic programming systems.

A model in QVR

This stochastic GRU language-model step draws update and reset gates, updates the hidden state, and scores the observed next token.

object Token : FinSet 256
object Embedded : Real 64
object Hidden : Real 128

morphism gate_z, gate_r : Embedded * Hidden -> Hidden ~ LogitNormal
morphism lm_head : Hidden -> Token ~ Categorical

program gru_step(x_t, h_prev) : Embedded * Hidden -> Token
    sample z <- gate_z(x_t, h_prev)
    sample r <- gate_r(x_t, h_prev)

    let reset_hidden = r * h_prev
    sample h_candidate <- Normal(reset_hidden, 0.5)

    let h = (1.0 - z) * h_prev + z * h_candidate
    observe next_token <- lm_head(h)
    return next_token

export gru_step

Install Quivers, download the full recurrent model, and check it through the command line:

pip install quivers
curl -LO https://raw.githubusercontent.com/FACTSlab/quivers/main/docs/examples/source/gru_lm.qvr
qvr check gru_lm.qvr

The tutorial starts with the core language and inference workflow. The examples gallery includes hierarchical and state-space models, mixture models, neural language models, formal grammars, and structural autoencoders.

Documentation

Installation and editors

Quivers requires Python 3.14 or later. Install optional interactive and editor support with:

pip install 'quivers[repl,lsp]'

The repository includes extensions for VS Code and Cursor and Zed. Both provide immediate syntax highlighting; qvr-lsp adds typed diagnostics, hover, definitions, references, completion, formatting, and semantic tokens.

Contributing

See CONTRIBUTING.md. Issues and pull requests are welcome at github.com/FACTSlab/quivers.

Acknowledgments

This project was developed by Aaron Steven White at the University of Rochester with support from the National Science Foundation (NSF-BCS-2237175 CAREER: Logical Form Induction, NSF-BCS-2040831 Computational Modeling of the Internal Structure of Events). It was architected and implemented with the assistance of Claude Code.

License

MIT. See LICENSE.

Metadata

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