Websocket.check: def of bend-kit-websocket@0.4.0.0
Import: import bend-kit-websocket@0.4.0.0/websocket.bend as Websocket
Lines 208-220 of bend-kit-websocket@0.4.0.0/websocket.bend: https://jend.leeeet.dev/read.txt?path=bend-kit-websocket@0.4.0.0/websocket.bend&start_line=208&end_line=220

import Base

# Does a server's head (up to its blank line) accept the upgrade? want is accept(key).
# Upgrade and Sec-WebSocket-Accept must each come once. No extension or subprotocol
# was asked for, so the server may name none (§4.1).
def check(+head: String, +want: String) -> Result<&1, &1, U32 & String, Unit>:
  verdict(Unit,
    first(reject(Bool.not(status(String.split(head, '\n'))), 1002, "status line is not HTTP/1.1 101"),
    first(reject(Bool.not(lines.ok(headers(head))), 1002, "malformed header line"),
    first(reject(Bool.not(value.is(value.lower(field(head, "upgrade")), "websocket")), 1002, "Upgrade is not one websocket"),
    first(reject(Bool.not(tokens(fields(head, "connection"), "upgrade")), 1002, "Connection lacks Upgrade"),
    first(reject(Bool.not(value.is(field(head, "sec-websocket-accept"), want)), 1002, "Sec-WebSocket-Accept is not one match for the key"),
    first(reject(Bool.not(none(fields(head, "sec-websocket-extensions"))), 1002, "unrequested extension"),
      reject(Bool.not(none(fields(head, "sec-websocket-protocol"))), 1002, "unrequested subprotocol"))))))),
    Unit{})

Uses (20):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Bool.not
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Char
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Pair
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Result
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=String
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=String.split
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Unit
  https://jend.leeeet.dev/definition.txt?path=bend-kit-websocket@0.4.0.0/websocket.bend&name=field
  https://jend.leeeet.dev/definition.txt?path=bend-kit-websocket@0.4.0.0/websocket.bend&name=fields
  https://jend.leeeet.dev/definition.txt?path=bend-kit-websocket@0.4.0.0/websocket.bend&name=first
  https://jend.leeeet.dev/definition.txt?path=bend-kit-websocket@0.4.0.0/websocket.bend&name=headers
  https://jend.leeeet.dev/definition.txt?path=bend-kit-websocket@0.4.0.0/websocket.bend&name=lines.ok
  https://jend.leeeet.dev/definition.txt?path=bend-kit-websocket@0.4.0.0/websocket.bend&name=none
  https://jend.leeeet.dev/definition.txt?path=bend-kit-websocket@0.4.0.0/websocket.bend&name=reject
  https://jend.leeeet.dev/definition.txt?path=bend-kit-websocket@0.4.0.0/websocket.bend&name=status
  https://jend.leeeet.dev/definition.txt?path=bend-kit-websocket@0.4.0.0/websocket.bend&name=tokens
  https://jend.leeeet.dev/definition.txt?path=bend-kit-websocket@0.4.0.0/websocket.bend&name=value.is
  https://jend.leeeet.dev/definition.txt?path=bend-kit-websocket@0.4.0.0/websocket.bend&name=value.lower
  https://jend.leeeet.dev/definition.txt?path=bend-kit-websocket@0.4.0.0/websocket.bend&name=verdict