1	import Base
2	
3	# V's I/O: running a program with its arguments (the effect below), and reading and writing files with
4	# Base's File API.
5	
6	# ---- running a program ----
7	# Temporary: bend-kit-process does this, but no Bend version runs both it (2.0.27 only) and bend-kit-files (2.0.28+).
8	def Program.run(cmd: String, args: String) -> IO(Result<&1, &1, U32 & String, String>):
9	  import "./program_run.c"
10	  import "./program_run.js"
11	
12	def out_of(r: Result<&1, &1, U32 & String, String>) -> String:
13	  match r:
14	    case Done{out}:
15	      out
16	    case Fail{_}:
17	      ""
18	
19	def ok_of(r: Result<&1, &1, U32 & String, String>) -> Bool:
20	  match r:
21	    case Done{_}:
22	      True{}
23	    case Fail{_}:
24	      False{}
25	
26	# A program's standard output when it exits 0, else "".
27	def run(cmd: String, args: List<&2, String>) -> IO(String):
28	  do IO<String>:
29	    r : Result<&1, &1, U32 & String, String> <- Program.run(cmd, String.join(args, "\u{1f}"))
30	    return out_of(r)
31	
32	# Whether a program exits 0.
33	def succeeds(cmd: String, args: List<&2, String>) -> IO(Bool):
34	  do IO<Bool>:
35	    r : Result<&1, &1, U32 & String, String> <- Program.run(cmd, String.join(args, "\u{1f}"))
36	    return ok_of(r)
37	
38	def home() -> IO(String):
39	  do IO<String>:
40	    r : Result<&1, &1, U32 & String, String> <- IO.get_env("HOME")
41	    return Result.default(&1, &1, U32 & String, String, r, "")
42	
43	# ---- reading a file: its text, or "" when it cannot be read ----
44	def size_of(r: Result<&1, &1, U32 & String, U32>) -> U32:
45	  match r:
46	    case Done{n}:
47	      n
48	    case Fail{_}:
49	      0
50	
51	def text_of(r: Result<&1, &1, U32 & String, String>) -> String:
52	  match r:
53	    case Done{t}:
54	      t
55	    case Fail{_}:
56	      ""
57	
58	def read_done(r: File & Result<&1, &1, U32 & String, String>) -> IO(String):
59	  match r:
60	    case (f, got):
61	      do IO<String>:
62	        File.close(f)
63	        return text_of(got)
64	
65	def read_sized(r: File & Result<&1, &1, U32 & String, U32>) -> IO(String):
66	  match r:
67	    case (f, n):
68	      do IO<String>:
69	        got : File & Result<&1, &1, U32 & String, String> <- File.read(f, size_of(n))
70	        read_done(got)
71	
72	def read_opened(r: Result<&1, &1, U32 & String, File>) -> IO(String):
73	  match r:
74	    case Done{f}:
75	      do IO<String>:
76	        n : File & Result<&1, &1, U32 & String, U32> <- File.size(f)
77	        read_sized(n)
78	    case Fail{_}:
79	      IO.pure(String, "")
80	
81	def read_head_opened(r: Result<&1, &1, U32 & String, File>, max: U32) -> IO(String):
82	  match r:
83	    case Done{f}:
84	      do IO<String>:
85	        got : File & Result<&1, &1, U32 & String, String> <- File.read(f, max)
86	        read_done(got)
87	    case Fail{_}:
88	      IO.pure(String, "")
89	
90	# The first `max` bytes of a file ("" if unreadable): enough for what sits at its top, like imports.
91	def read_head(path: String, max: U32) -> IO(String):
92	  do IO<String>:
93	    r : Result<&1, &1, U32 & String, File> <- File.open(path, "r")
94	    read_head_opened(r, max)
95	
96	def read(path: String) -> IO(String):
97	  do IO<String>:
98	    r : Result<&1, &1, U32 & String, File> <- File.open(path, "r")
99	    read_opened(r)
100	
101	# ---- writing a file ----
102	def after_write(r: File & Result<&1, &1, U32 & String, Unit>) -> IO(Unit):
103	  match r:
104	    case (f, _):
105	      File.close(f)
106	
107	def write_opened(r: Result<&1, &1, U32 & String, File>, text: String) -> IO(Unit):
108	  match r:
109	    case Done{f}:
110	      do IO<Unit>:
111	        w : File & Result<&1, &1, U32 & String, Unit> <- File.write(f, text)
112	        after_write(w)
113	    case Fail{_}:
114	      IO.die(Unit, 1, "cannot write a file")
115	
116	def write(path: String, text: String) -> IO(Unit):
117	  do IO<Unit>:
118	    r : Result<&1, &1, U32 & String, File> <- File.open(path, "w")
119	    write_opened(r, text)
120	
121	def keep_filled(c: Bool, x: String, rest: List<&2, String>) -> List<&2, String>:
122	  match c:
123	    case True{}:
124	      x <> rest
125	    case False{}:
126	      rest
127	
128	# The trimmed, non-empty strings.
129	def nonempty(xs: List<&2, String>) -> List<&2, String>:
130	  match xs:
131	    case []:
132	      []
133	    case +x <> rest:
134	      keep_filled(Bool.not(String.is_empty(String.trim(x))), String.trim(x), nonempty(rest))
135