Precise navigation of paths

Serpentine is a small library for handling the abstract notion of paths, distinguishing between relative and absolute forms, rooted on some value. This may be useful for representing paths on a filesystem, resources on an HTTP server, descendants in a family tree, or many other concepts which follow a hierarchical pattern.

• representations of hierarchical paths
• designed for extension and use in many concrete contexts
• distinguishes between absolute and relative paths

The type Root defines a "root", beneath which any number of possible Path instances may exist in a hierarchy, and the methods parent, ancestor and / may be used to navigate between them. For abstract paths, the value Base can serve as a root node for a path hierarchy.

Here are some examples:

val crustaceans = Base / "eukaryota" / "animalia" / "arthropods" / "crustaceans"
val arthropods = crustaceans.parent
val animalia = crustaceans.ancestor(2)

Paths may be further distinguished as Path.Relative or Path.Absolute, where a Relative may be converted into an Absolute by calling the Path#absolute method, and passing an absolute path to which the relative path should be considered relative to. The result is typed as Path.Absolute.

Path objects, whether absolute or relative, serialize with toString according to the delimiters in their root, which are defined in terms of a base name (for example, / or classpath:) and a separator (for example, \, / or .).

Any implementation of Root should define these values, prefix and separator, respectively. For example, the definition,

object Domain extends Root(prefix = "", separator = ".")

would ensure that,

Domain / "www" / "example" / "com"

would serialize to the string "www.example.com".

Note that the separator is not included between the prefix and the first path element when serializing, so may need to be included in the prefix value itself.

The method ++ can add a Relative path to an Absolute path, and return a new Absolute path.

Similarly, Absolute#relativeTo takes another Absolute path and returns a Relative instance that, when applied with ++ to the first path, produces the second path.

The Absolute#conjunction method will find the closest common parent of the path and its parameter.

Note that Paths are not aware of their children, so there is no children method, but this may be provided by individual implementations.

Many operations on Paths may attempt (directly or indirectly) to access the parent of the root. This is not possible, and if this happens, a RootBoundaryExceeded exception will be thrown.

Given that a relative path is (by definition) not attached to any particular root, all instances of Root#Path.Relative inherit from GenericRelative which gives users the choice, when implementing APIs that accept relative paths, between accepting any kind of relative path (regardless of its origin) and accepting just those originating from a particular root.

Serpentine is classified as fledgling. For reference, Soundness projects are categorized into one of the following five stability levels:

• embryonic: for experimental or demonstrative purposes only, without any guarantees of longevity
• fledgling: of proven utility, seeking contributions, but liable to significant redesigns
• maturescent: major design decisions broady settled, seeking probatory adoption and refinement
• dependable: production-ready, subject to controlled ongoing maintenance and enhancement; tagged as version 1.0.0 or later
• adamantine: proven, reliable and production-ready, with no further breaking changes ever anticipated

Projects at any stability level, even embryonic projects, can still be used, as long as caution is taken to avoid a mismatch between the project's stability level and the required stability and maintainability of your own project.

Serpentine is designed to be small. Its entire source code currently consists of 950 lines of code.

Serpentine will ultimately be built by Fury, when it is published. In the meantime, two possibilities are offered, however they are acknowledged to be fragile, inadequately tested, and unsuitable for anything more than experimentation. They are provided only for the necessity of providing some answer to the question, "how can I try Serpentine?".

1. Copy the sources into your own project

   Read the fury file in the repository root to understand Serpentine's build structure, dependencies and source location; the file format should be short and quite intuitive. Copy the sources into a source directory in your own project, then repeat (recursively) for each of the dependencies.

   The sources are compiled against the latest nightly release of Scala 3. There should be no problem to compile the project together with all of its dependencies in a single compilation.

2. Build with Wrath

   Wrath is a bootstrapping script for building Serpentine and other projects in the absence of a fully-featured build tool. It is designed to read the fury file in the project directory, and produce a collection of JAR files which can be added to a classpath, by compiling the project and all of its dependencies, including the Scala compiler itself.

   Download the latest version of wrath, make it executable, and add it to your path, for example by copying it to /usr/local/bin/.

   Clone this repository inside an empty directory, so that the build can safely make clones of repositories it depends on as peers of serpentine. Run wrath -F in the repository root. This will download and compile the latest version of Scala, as well as all of Serpentine's dependencies.

   If the build was successful, the compiled JAR files can be found in the .wrath/dist directory.

Contributors to Serpentine are welcome and encouraged. New contributors may like to look for issues marked beginner.

We suggest that all contributors read the Contributing Guide to make the process of contributing to Serpentine easier.

Please do not contact project maintainers privately with questions unless there is a good reason to keep them private. While it can be tempting to repsond to such questions, private answers cannot be shared with a wider audience, and it can result in duplication of effort.

Serpentine was designed and developed by Jon Pretty, and commercial support and training on all aspects of Scala 3 is available from Propensive OÜ.

A path which is serpentine may be a challenge to navigate, which is where Serpentine can help.

In general, Soundness project names are always chosen with some rationale, however it is usually frivolous. Each name is chosen for more for its uniqueness and intrigue than its concision or catchiness, and there is no bias towards names with positive or "nice" meanings—since many of the libraries perform some quite unpleasant tasks.

Names should be English words, though many are obscure or archaic, and it should be noted how willingly English adopts foreign words. Names are generally of Greek or Latin origin, and have often arrived in English via a romance language.

The logo shows a serpentine section of river, meandering.

Serpentine is copyright © 2024 Jon Pretty & Propensive OÜ, and is made available under the Apache 2.0 License.