def fold

stelliferous@0.0.2.0 · proofs/traversal_witness.bend:277

import Base
import stelliferous@0.0.2.0/traversal_loop.bend as Loop
import stelliferous@0.0.2.0/traversal_array.bend as Traversal

277def fold(~Reader: Type,~Element: Data,~Accumulator: Data,~Context: Data,~ReaderEvidence: @-reader: Reader -> Data,
278  ~read: Reader -> Context -> U32 -> Reader & Element,~combine: Accumulator -> Element -> Accumulator,
279  ~read_preserves: @-reader: Reader -> @context: Context -> @index: U32 -> ReaderEvidence(reader) ->
280    Sample<Reader,Element,reader,read(reader,context,index)>,
281  count: Nat,-reader: Reader,position: U32,context: Context,-initial: Accumulator,reader_evidence: ReaderEvidence(reader)) ->
282  {first(~Reader,~Accumulator,Traversal.fold(~Reader,~Element,~Accumulator,~Context,~read,~combine,count,position,reader,initial,context)) == reader : Reader}:
283  fold_finished(~Reader,~Accumulator,~Context,reader,
284    Loop.run(~Traversal.State<&1,&2,Reader,Accumulator,Context>,~Traversal.fold_step(~Reader,~Element,~Accumulator,~Context,~read,~combine),count,
285      Traversal.State{reader,initial,position,context}),
286    fold_run(~Reader,~Element,~Accumulator,~Context,~ReaderEvidence,~read,~combine,~read_preserves,count,reader,
287      Traversal.State{reader,initial,position,context},reader_evidence,FoldEvidence{initial,position,context,{==}}))