1	import Base
2	import bend-net-json@0.3.0.0/json.bend as Json
3	
4	# Building a plugin's JSON: optional keys are left out when absent.
5	
6	def with.go(kvs: List<&2, Sigma<&2, &2, String, _ => Json.Val>>, m: Map<&2, Json.Val>) -> Map<&2, Json.Val>:
7	  match kvs:
8	    case []:
9	      m
10	    case (k, v) <> rest:
11	      with.go(rest, Map.set(&2, Json.Val, m, k, v))
12	
13	def obj(kvs: List<&2, Sigma<&2, &2, String, _ => Json.Val>>) -> Json.Val:
14	  Json.Obj{with.go(kvs, Map.new(&2, Json.Val))}
15	
16	# A key, or nothing when its value is absent.
17	def opt(+k: String, m: Maybe<&2, Json.Val>) -> List<&2, Sigma<&2, &2, String, _ => Json.Val>>:
18	  match m:
19	    case Some{v}:
20	      [(k, v)]
21	    case None{}:
22	      []
23	
24	def text(m: Maybe<&2, String>) -> Maybe<&2, Json.Val>:
25	  match m:
26	    case Some{s}:
27	      Some{Json.Str{s}}
28	    case None{}:
29	      None{}
30	
31	def number(m: Maybe<&2, Nat>) -> Maybe<&2, Json.Val>:
32	  match m:
33	    case Some{n}:
34	      Some{Json.Num{Nat.show(n)}}
35	    case None{}:
36	      None{}
37	
38	def flag(m: Maybe<&2, Bool>) -> Maybe<&2, Json.Val>:
39	  match m:
40	    case Some{b}:
41	      Some{Json.Flag{b}}
42	    case None{}:
43	      None{}
44	
45	# A key that is true, or nothing: false is every flag's default.
46	def when_true(+k: String, b: Bool) -> List<&2, Sigma<&2, &2, String, _ => Json.Val>>:
47	  match b:
48	    case True{}:
49	      [(k, Json.Flag{True{}})]
50	    case False{}:
51	      []
52	
53	def strs(xs: List<&2, String>) -> List<&2, Json.Val>:
54	  match xs:
55	    case []:
56	      []
57	    case x <> rest:
58	      Json.Str{x} <> strs(rest)
59	
60	def texts(xs: List<&2, String>) -> Json.Val:
61	  Json.Arr{strs(xs)}
62	
63	def cat(xss: List<&2, List<&2, Sigma<&2, &2, String, _ => Json.Val>>>) -> Json.Val:
64	  obj(List.concat(&2, Sigma<&2, &2, String, _ => Json.Val>, xss))
65