Document Import From Derivation

[fricklerhandwerk]

Problem

Currently the "Import From Derivation" (IFD) pattern is only documented in the NixOS Wiki, and therefore not curated by Nixpkgs maintainers. Even the manual refers to the Wiki.

This means, there is no authoritative reference on the concept.

Checklist

• checked latest Nixpkgs manual (source) and latest NixOS manual (source)
• checked open documentation issues for possible duplicates
• checked open documentation pull requests for possible solutions

Proposal

Document IFD and Nixpkgs' policy in the Nixpkgs manual in full detail.

Related:

• Nix manual: allow-import-from-derivation
• NixOS Wiki: Import From Derivation

Related discussions involving IFD:

• lib: Add find and findSuffix to lib.filesystem #188354 (comment)
• source combinators: extend, trace, cutAt, focusAt and more #112083

[FRidh]

Even the manual refers to the Wiki.

This should then refer to the Nix manual instead as IFD is a Nix concept. The Nixpkgs policy regarding IFD should indeed be in the Nixpkgs manual.