superfunc / tp

Strongly Typed Paths for Idris

TP: An idris package for typed, unix-style, path manipulation.

Overview:

This repo provides an idris package, System.Posix.Paths for typed path manipulation. I'd like to add some neat usage of dependent types to this library, but the initial library just has Haskell-style, strongly-typed, paths.

The core pieces are:

• Path: An opaque path type that encodes the kind(file/directory) and anchoring(absolute/relative).
• mkRelativeFile: Create a relative file from a string repr.
• mkRelativeDirectory: Create a relative directory from a string repr.
• mkAbsoluteFile: Create an absolute file from a string repr.
• mkAbsoluteDirectory: Create an absolute directory from a string repr.
• concat: Join two paths together.
• str: Get a string repr of a path.
• Eq: Paths can be compared by usual equality methods.
• Show: Pretty print path information.

Note that many of these operations, concat for example, restrict the type of paths that can be used via the kind/anchoring, preventing a large class of errors. In other cases, we use Maybe to encode possible failure, such as in the case of the mk functions.

Usage:

The tests provide decent examples for the time being. Once things have been cleaned up, I'll try to provide more thorough examples here.

Dependencies:

None

Disclaimer(s):

0. Contributions are very welcome.

1. This work is my sole effort and is in no way associated with or sponsored by my current, past, or future employer(s).

tp's Issues

Remove nontotal functions

Add dependently typed variants for existing API

Clean up pack/unpack nonsense

Currently the code turns strings into char lists all over the place(and back) because its easier to write recursive functions on them. This should be cleaned up somehow.

Consider Different Structure

Transferring a nice sugg from @gallais on reddit to here:

Wouldn't it make sense to store the path as:

• a starting point (i.e. whether it's relative or absolute)
• a list of directory names
• (possibly) a file name and (possibly) an extension rather than a sum type of strings? In other words: expose the structure rather than storing validated raw data.

Add more examples

Real world usage interacting with IO would be ideal.