Add -npartial for arbitrary partial application

dash-functional.el

@@ -45,6 +45,28 @@ When called, the returned function calls FN with the additional
 args first and then ARGS."
   (lambda (&rest args-before) (apply fn (append args-before args))))
 
+(defun -npartial (n fn &rest args)
+  "Takes an offset N, a function FN and fewer than the normal
+arguments to FN, and returns a function which takes a variable
+number of additional ARGS, similar to `-partial' and
+`-rpartial'.
+
+ARGS will be spliced in after the Nth element in the additional
+args. If N is negative, -1 is taken to be the final item, -2, the
+penultimate item, etc.
+
+This function satisfies the following laws:
+
+    (-npartial 0 ...) ≡ (-partial ...)
+    (-npartial -1 ...) ≡ (-rpartial ...)"
+  (lambda (&rest args-around) (apply fn (if (< n 0)
+                                            (append (-drop-last (1+ n) args-around)
+                                                    args
+                                                    (-take-last (1+ n) args-around))
+                                          (append (-take n args-around)
+                                                  args
+                                                  (-drop n args-around))))))
+
 (defun -juxt (&rest fns)
   "Takes a list of functions and returns a fn that is the
 juxtaposition of those fns. The returned fn takes a variable

dash-template.texi

@@ -439,6 +439,9 @@ script to create an info manual.
 @item
 @uref{https://github.com/occidens,William West} made @code{-fixfn}
 more robust at handling floats.
+@item
+@uref{https://github.com/daantjie,Daniel Oosthuizen} added @code{-npartial}
+for arbitrary partial application.
 @end itemize
 
 Thanks!

dev/examples.el

@@ -1055,6 +1055,12 @@ new list."
       (funcall (-rpartial '- 5) 8) => 3
       (funcall (-rpartial '- 5 2) 10) => 3)
 
+    (defexamples -npartial
+      (funcall (-npartial 1 (lambda (a b c) (+ a (* b c))) 5) 2 3) => 17
+      (funcall (-npartial 2 (lambda (a b c d) (+ a (* b c) d)) 3) 2 4 5) => 19
+      (funcall (-npartial -1 #'concat "last " "words.") "These " "are " "the ") => "These are the last words."
+      (funcall (-npartial 3 (lambda (a b c d e f) (concat a b c d e f ".")) "penultimate " "words ") "I'll " "put " "the " "here") => "I'll put the penultimate words here.")
+
     (defexamples -juxt
       (funcall (-juxt '+ '-) 3 5) => '(8 -2)
       (-map (-juxt 'identity 'square) '(1 2 3)) => '((1 1) (2 4) (3 9)))

readme-template.md

@@ -245,7 +245,7 @@ Change `readme-template.md` or `examples-to-docs.el` instead.
  - [Vasilij Schneidermann](https://github.com/wasamasa) contributed `-some`.
  - [William West](https://github.com/occidens) made `-fixfn` more robust at handling floats.
  - [Cam Saül](https://github.com/camsaul) contributed `-some->`, `-some->>`, and `-some-->`.
-
+ - [Daniel Oosthuizen](https://github.com/daantjie)} added `-npartial` for arbitrary partial application.
 Thanks!
 
 ## License