PureScript Binary Builder

The `build-purescript` Node.js module, currently at version 0.4.1, provides a programmatic interface for compiling the PureScript compiler binary (`purs`) directly from its source code. It handles the complete lifecycle, including downloading the PureScript GitHub repository, setting up the necessary Haskell toolchain via `stack`, and then compiling and installing the `purs` executable into the current working directory. The library exposes its operations as an Observable stream, allowing developers to subscribe to various progress events such as `download`, `setup`, and `build` completion, along with real-time output from the underlying `stack` commands. This detailed event reporting is a key differentiator, offering transparency and control over what is typically a complex and opaque build process for Haskell-based applications, making it suitable for automated build pipelines or environments requiring dynamic provisioning of specific PureScript compiler versions.