def PipeSession.ask.go

bend-pipe-session@0.2.0.0 · impl.bend:62

import Base
import bend-stdio-pipes@0.2.0.0/impl.bend as Stdio

62# said holds the lines so far, the last first; fuel bounds the lines, far beyond any answer.
63def PipeSession.ask.go(
64  fuel: Nat,
65  at: File & Heard,
66  +until: String,
67  +line_cap: U32,
68  said: List<&2, String>
69) -> IO(File & Result<&1, &1, U32 & String, List<&2, String>>):
70  match fuel:
71    case 0n:
72      match at:
73        case (out, _):
74          IO.pure(
75            File & Result<&1, &1, U32 & String, List<&2, String>>,
76            (out, Fail{(5, "the program said too many lines before " ++ until)})
77          )
78    case 1n+rest:
79      match at:
80        case (out, Failed{error}):
81          IO.pure(File & Result<&1, &1, U32 & String, List<&2, String>>, (out, Fail{error}))
82        case (out, Ended{}):
83          IO.pure(
84            File & Result<&1, &1, U32 & String, List<&2, String>>,
85            (out, Fail{(PipeSession.ended(), "the program ended before it said " ++ until)})
86          )
87        case (out, Last{text}):
88          IO.pure(
89            File & Result<&1, &1, U32 & String, List<&2, String>>,
90            (out, Done{List.reverse(&2, String, text <> said)})
91          )
92        case (out, Line{text}):
93          do IO<File & Result<&1, &1, U32 & String, List<&2, String>>>:
94            read: File
95              & Result<&1, &1, U32 & String, Maybe<String>> <- Stdio.read_line(out, line_cap)
96            PipeSession.ask.go(rest, Heard.read(read, until), until, line_cap, text <> said)