src/run/bend.bend source

src/run/bend.bend on the hub · documented module

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