1	# run/bend: which bend is on the PATH, asked the way that bend will answer.
2	#
3	# bend has had the question two ways round. Up to 2.0.16 it is `bend --version`
4	# and `bend version` is "no such file: version"; from 2.0.18 on it is `bend
5	# version` and the flag is "unknown option --version". Either way the spelling
6	# it does not know exits non-zero, which looks exactly like a bend that is not
7	# installed — so a caller that asks only one way cannot tell a missing bend
8	# from an old one, and ez has two callers that need the banner: doctor's
9	# report and the toolchain part of a cache key.
10	# Asking both ways, current spelling first, is the whole of this module.
11	import Base
12	import 0xabe575924687afad4cee1a2c1194d639/main.bend as R
13	
14	# the older spelling, tried only when the current one was not understood
15	def version.older(ok: Bool, out: String) -> IO(String):
16	  match ok:
17	    case True{}:
18	      IO.pure(String, out)
19	    case False{}:
20	      R.exec(["bend", "--version"])
21	
22	# `bend` asked which bend it is, as a run's answer: the status line, then the
23	# banner. A bend that is not on the PATH fails both spellings, so the status
24	# an absent bend answers with is still the one the caller sees.
25	def version() -> IO(String):
26	  do IO<String>:
27	    +out : String <- R.exec(["bend", "version"])
28	    version.older(R.ok(out), out)