def once.go

ezx@1.11.0.0 · src/ledger/ignore.bend:217

import Base
import ezx@1.11.0.0/src/ledger/manifest.bend as M

217# each hash once, where it first appears, passing over any `seen` already
218# holds. An empty hash names no tree; `M.parse` refuses a dependency with
219# none, so that only guards a model built by hand.
220def once.go(hs: List<&2, String>, +seen: List<&2, String>) -> List<&2, String>:
221  match hs:
222    case []:
223      []
224    case +h <> t:
225      +skip = Bool.or(String.is_empty(h), named(seen, h))
226      once.put(skip, h, once.go(t, once.seen(skip, h, seen)))