(el) - JavaScript

array elements selected by position and/or value (used with (arr ...))

(el pos? val?)

Where:

1. pos: position in the list (1-based) *
2. val: value at that position *

Behavior

• With only a position, (el N) matches arrays that have an element at that position.
• Without position or value, (el) only matches non-empty arrays.

Examples

Extract route handlers from [method, path, handler] tuples.

(arr (el 3 (:into)))

Selects in lines { 2, 3 } but not in { 4 }:

const routes = [
  ["GET", "/health", health],
  ["POST", "/users", createUser],
  ["GET", "/status"]
]

---

Find arrays that use null as a sentinel in the first slot.

(arr (el 1 (null)))

Selects in lines { 1, 3 } but not in { 2 }:

const rows1 = [null, "ready"]
const rows2 = ["ready", null]
const rows3 = [null, "done"]

---

Locate arrays that include the beta flag anywhere in the list.

(arr (el _ (str "beta")))

Selects in lines { 1, 3 } but not in { 2 }:

const flags1 = ["beta", "dark-mode"]
const flags2 = ["stable", "dark-mode"]
const flags3 = ["dark-mode", "beta"]

---

Arguments

pos

1. Number

Does NOT support: Composition — Free-form Selection — Refinement — Replacement

val

1. Identifier: shorthand for (id)
   
2. String: shorthand for (str)
   
3. (:into)
4. (:nearest)
5. (:and)
6. (:or)
7. (:not)
8. (:text)
9. (:kind)
10. (:replace)
11. (:replace-in)
12. (:capture)
13. (:ref)
14. (arr)
15. (attr)
16. (bool)
17. (call)
18. (child)
19. (comp)
20. (export)
21. (fun)
22. (id)
23. (id+)
24. (import)
25. (jsx)
26. (mem)
27. (null)
28. (num)
29. (obj)
30. (of)
31. (prop)
32. (regex)
33. (regex+)
34. (str)
35. (str*)
36. (str+)
37. (tpl)
38. (tpl*)
39. (var)