1	# shake/args: the process's arguments, each word reusable, and the values of a
2	# spec's env vars, internal (main.bend exports them). `IO.args` answers a `&1`
3	# list that starts with the program as invoked (bend 2.0.32 and later); the
4	# rest of a program reads the line more than once, so `words` drops that head
5	# and copies the rest.
6	import Base
7	import ./cli.bend as C
8	
9	# a &1 list copied to &2
10	def copy(xs: List<&1, String>) -> List<&2, String>:
11	  match xs:
12	    case Nil{}:
13	      Nil{}
14	    case Con{+h, t}:
15	      h <> copy(t)
16	
17	# the arguments of an IO.args line: every word after the program name, copied
18	def words(xs: List<&1, String>) -> List<&2, String>:
19	  match xs:
20	    case Nil{}:
21	      Nil{}
22	    case Con{_h, t}:
23	      copy(t)
24	
25	# the process's arguments, without the program name
26	def argv() -> IO(List<&2, String>):  # noqa: L001 IO: reads argv (SHAKE-TRUST-4)
27	  IO.bind(List<&1, String>, List<&2, String>, IO.args(),
28	    xs => IO.pure(List<&2, String>, words(xs)))
29	
30	# a name and its value in front of the pairs, when `IO.get_env` found one
31	def kept(
32	  +name: String,
33	  got: Result<&1, &1, U32 & String, String>,
34	  rest: List<&2, C.Var>
35	) -> List<&2, C.Var>:
36	  match got:
37	    case Done{vv}:
38	      (name, vv) <> rest
39	    case Fail{_e}:
40	      rest
41	
42	# the names that are set, each with its value, in order
43	def vars(names: List<&2, String>) -> IO(List<&2, C.Var>):  # noqa: L001 IO: reads env vars (SHAKE-TRUST-5)
44	  match names:
45	    case Nil{}:
46	      IO.pure(List<&2, C.Var>, [])
47	    case Con{+hh, tt}:
48	      IO.bind(Result<&1, &1, U32 & String, String>, List<&2, C.Var>, IO.get_env(hh),
49	        got => IO.bind(List<&2, C.Var>, List<&2, C.Var>, vars(tt),
50	          rest => IO.pure(List<&2, C.Var>, kept(hh, got, rest))))
51	
52	# the env vars a spec names that are set, each with its value
53	def env_vars(spec: C.Cli) -> IO(List<&2, C.Var>):  # noqa: L001 IO: reads env vars (SHAKE-TRUST-5)
54	  vars(C.env.names(spec))