empathy is a modern library for typed path manipulation. It takes advantage of newer GHC features like DataKinds, Backpack, and custom type errors so as to minimize the library footprint while yielding the maximum amount of type safety.
- Platform details are abstracted away with Backpack. Every such detail is accounted for in a signature file.
- Path literals are constructed using type-level
Symbols, not value-levelStrings. (You will get a custom type error if you attempt to use aStringliteral for a path). This will let us do compile-time parsing to enforce well-formedness of paths; that is, asking the string"/usr/bin/"to represent anything but an absolute directory will be a compile-time error. - Information about the relative/absolute or file/directory nature of a given path is stored on the type-level rather than the value level.
- It comes with batteries included (
optparse-applicativeparsers,HashableandNFDatainstances, etc.).
I evaluated all of the libraries and wasn't happy with any of them. pathtype came closest to my needs, but bears historical cruft and doesn't take full advantage of newer GHC features. path requires Template Haskell, which is avoidable in an era of type-level strings. data-filepath is unmaintained.
Alas, yes. Until commercialhaskell/stack#2540 is fixed, you won't be able to use this library from a Stack project. (I should point out, however, that switching from stack to cabal-install v3.0 is generally pretty easy.)
- Currently there is no way to access the last element of a type-level string in anything other than linear time. As such, the
absRel-style constructors don't check for trailing slashes.
empathy is open-source software provided to you under the terms of the Hippocratic License. Due to the fact that the Hippocratic license does not have an SPDX identifier yet, the Cabal file states that it is MIT licensed; this will be addressed when the SPDX allocates an identifier for the HL.