Outside Module Evaluation

Using import-tree as a File Lister

import-tree doesn’t have to produce module imports. You can use it to get a plain list of files:

(import-tree.withLib pkgs.lib).leafs ./modules
# => [ /path/to/modules/a.nix /path/to/modules/b.nix ]

withLib

Outside module evaluation, import-tree needs access to lib (specifically lib.filesystem.listFilesRecursive). Call .withLib before .leafs or .pipeTo:

import-tree.withLib lib

Omitting .withLib when calling .leafs produces an error: "You need to call withLib before trying to read the tree."

leafs

.leafs returns a configured import-tree that, when given a path, produces a flat list of discovered files:

(import-tree.withLib lib).leafs ./src
# => [ ./src/main.nix ./src/utils.nix ]

files

.files is a shortcut for .leafs.result: returns the list directly when paths have already been added via .addPath:

import-tree
  (i: i.addPath ./modules)
  (i: i.withLib lib)
  (i: i.files)

pipeTo

.pipeTo takes a function that receives the list of discovered paths, letting you process the results:

import-tree (it: it.withLib lib) (it: it.pipeTo builtins.length) ./modules
# => 5  (number of .nix files)

Combine with .map for powerful pipelines:

import-tree
  (i: i.map import)
  (i: i.pipeTo lib.length)
  (i: i.withLib lib)
  (i: i ./modules)

result

.result evaluates the import-tree with an empty path list, useful when paths are already configured via .addPath:

(import-tree.addPath ./modules).result
# equivalent to:
(import-tree.addPath ./modules) []