def seen.has

ezx@1.11.0.0 · src/pkg/pkg.bend:496

import Base

496# whether a name is already among the ones the walk has reached. Base's
497# `List.contains` applies an erased equality, which falls outside the
498# termination check; this scan is structural.
499def seen.has(xs: List<&2, String>, +want: String) -> Bool:
500  match xs:
501    case []:
502      False{}
503    case +h <> t:
504      seen.has.step(String.eq(h, want), _u => seen.has(t, want))