core.cli — CLI helpers

Import with << core.cli. See the corelib index and examples/cli.qn.

Thin, pipe-friendly helpers over the entry point’s args :: []Text and env :: [|Text => Text|]. The data is always the first parameter, so env |> getEnv("PATH") and args |> hasFlag("-v") read naturally.

Function	Result
getEnv(env :: [|Text => Text|], key :: Text) -> Result	Look key up in the env Map; Ok(value) if the variable is set, else NotOk. The ergonomic name for the Map’s own env.get(key).
hasFlag(args :: []Text, flag :: Text) -> Bool	true when the bare flag appears in args. The name works with or without a leading -- (so "verbose" and "--verbose" both match an argument "--verbose").
getOpt(args :: []Text, name :: Text) -> Result	Collect the option’s values (argv[0] skipped), recognising both --name value and --name=value; the name works with or without --. Returns Ok([]Text) of the values in argv order (an option may repeat), or NotOk(name) when no value is found — the name never appears, or appears only as a trailing --name with nothing after it. (The --name=value form always supplies a value, even the empty one in --name=.)

<< core.cli
^ = (args :: []Text, env :: [|Text => Text|]) -> Num => <
  home :: Text = env |> getEnv("HOME") ? | Ok(v) => v | NotOk(_) => "?"
  verbose :: Bool = args |> hasFlag("-v")
  outputs :: []Text = args |> getOpt("--out") ? | Ok(vs) => vs | NotOk(_) => args.filter(x => false)
  verbose ? 0 : outputs.size
>

(See examples/cli.qn.)