1	# src/answer: reading an answer, which is the exit status on its own first
2	# line, then everything the program printed.
3	import Base
4	
5	# one char of the status: a newline ends it, and any other char is part of it,
6	# with the rest of the status read only then
7	def code.at(nl: Bool, +ch: Char, rest: Unit -> String) -> String:
8	  match nl:
9	    case True{}:
10	      SNil{}
11	    case False{}:
12	      SCon{ch, rest(Unit{})}
13	
14	# the exit status a run answered with: the answer up to its first newline.
15	# It reads no further, so a long body costs nothing.
16	def code(out: String) -> String:
17	  match out:
18	    case SNil{}:
19	      SNil{}
20	    case SCon{+ch, tail}:
21	      code.at(Char.is_eq(ch, '\n'), ch, _u => code(tail))
22	
23	# one char before the body: a newline starts the body, which is the rest as
24	# it stands, and any other char is still the status
25	def text.at(nl: Bool, +tail: String, rest: Unit -> String) -> String:
26	  match nl:
27	    case True{}:
28	      tail
29	    case False{}:
30	      rest(Unit{})
31	
32	# what the program printed, stdout and stderr together: the answer after its
33	# first newline, or nothing when it has none. The body is returned as it
34	# stands, never walked.
35	def text(out: String) -> String:
36	  match out:
37	    case SNil{}:
38	      SNil{}
39	    case SCon{ch, +tail}:
40	      text.at(Char.is_eq(ch, '\n'), tail, _u => text(tail))
41	
42	# a run that finished with status 0
43	def ok(+out: String) -> Bool:
44	  String.eq(code(out), "0")