1	import Base
2	
3	# V's I/O: run a program (a C effect, see proc_run.c) and write a file (Bend's File API).
4	
5	def Proc.run(cmd: String) -> IO(Result<&1, &1, U32 & String, String>):
6	  import "./proc_run.c"
7	
8	# Standard output of a command; "" if it failed.
9	def out_of(r: Result<&1, &1, U32 & String, String>) -> String:
10	  match r:
11	    case Done{v}:
12	      v
13	    case Fail{_}:
14	      ""
15	
16	def ok_of(r: Result<&1, &1, U32 & String, String>) -> Bool:
17	  match r:
18	    case Done{_}:
19	      True{}
20	    case Fail{_}:
21	      False{}
22	
23	def sh(cmd: String) -> IO(String):
24	  do IO<String>:
25	    r : Result<&1, &1, U32 & String, String> <- Proc.run(cmd)
26	    return out_of(r)
27	
28	def ok(cmd: String) -> IO(Bool):
29	  do IO<Bool>:
30	    r : Result<&1, &1, U32 & String, String> <- Proc.run(cmd)
31	    return ok_of(r)
32	
33	def after_write(r: File & Result<&1, &1, U32 & String, Unit>) -> IO(Unit):
34	  match r:
35	    case (f, _):
36	      File.close(f)
37	
38	def write_opened(r: Result<&1, &1, U32 & String, File>, text: String) -> IO(Unit):
39	  match r:
40	    case Done{f}:
41	      do IO<Unit>:
42	        w : File & Result<&1, &1, U32 & String, Unit> <- File.write(f, text)
43	        after_write(w)
44	    case Fail{_}:
45	      IO.die(Unit, 1, "cannot write file")
46	
47	def write_file(path: String, text: String) -> IO(Unit):
48	  do IO<Unit>:
49	    r : Result<&1, &1, U32 & String, File> <- File.open(path, "w")
50	    write_opened(r, text)