SwiftStanLibrary

A reusable, distributable Swift library for orchestrating cmdstan and generating Stan models from a Swift DSL. macOS 14+; Swift 6. No external dependencies.

Extracted and curated from SwiftStan, which also bundles a command-line tool. This package is library-only.

Products

• SwiftStan — the library module (import as import SwiftStan).

Public API

cmdstan commands (return (status: String, error: String))

Function	Description
compile(model:arguments:cmdstan:verbose:install:force:)	Compile a Stan model via make
sample(model:arguments:cmdstan:verbose:nosummary:install:)	Run HMC/NUTS sampling
optimize(model:arguments:cmdstan:verbose:)	MAP optimization
pathfinder(model:arguments:cmdstan:verbose:)	Pathfinder variational
laplace(model:arguments:cmdstan:verbose:)	Laplace approximation
generated_Quantities(model:arguments:cmdstan:verbose:)	Post-sampling generated quantities
stansummary(model:arguments:cmdstan:verbose:)	Run cmdstan's stansummary
ulamPipeline(model:cmdstan:verbose:force:arguments:)	Full pipeline: alist→Stan→compile→sample

All cmdstan commands take cmdstan: String (path to the cmdstan installation) and model: String (name of the case under ~/Documents/StanCases/, configurable via $STAN_CASES). They return (String, String) — .0 is a human-readable status, .1 is an error message ("" on success).

File-translation commands (throws → URL)

Function	Description
stancode(model:verbose:)	alist.R → Stan source (in-process, fast)
stan2alist(model:verbose:force:)	Stan source → alist.R (reverse)
alist2dsl(model:verbose:)	alist.R → Swift result-builder DSL driver
csv2json(model:verbose:)	CSV data file → data.json for cmdstan
runinfo(model:verbose:)	Clean and rewrite the cmdstan run-info JSON

Swift DSL (result-builder API)

Build Stan models directly in Swift without an R alist file:

import SwiftStan

let model = UlamModel(data: ["y": .integer([0,1,0,1,1]), "x": .real([1.0,2.0,3.0,4.0,5.0])]) {
  Likelihood("y", .bernoulli(p: "p"))
  Link(.logit, lhs: "p", rhs: "a + b*x")
  Prior("a", .normal(0, 1.5))
  Prior("b", .normal(0, 0.5))
}

let stanCode = try stancode(model)  // → Stan source String

Path resolution

All commands read/write under $STAN_CASES/<name>/{Preliminaries,Results}/ (default ~/Documents/StanCases/). Use casePaths(for: model) to navigate the layout. Run info is accessible via readRunInfo(dirUrl:modelName:).

Constraints

• macOS 14+ only — the library shells out to make, swiftc, and cmdstan binaries via Foundation.Process.
• dsl2stan is not included (it requires the package source tree to recompile via swiftc). The in-process stancode path covers alist→Stan without swiftc.
• $CMDSTAN must point to a cmdstan installation; alternatively pass the path explicitly to each command.

Building

swift build
swift test                              # unit tests only (no cmdstan required)
CMDSTAN=/path/to/cmdstan swift test    # unit + integration tests

License

MIT — see LICENSE.