proofs/tensor_access_certificate.bend

stelliferous@0.0.3.0 · 403 lines · 0 definitions

1# Discharge the reader premises for the actual tensor traversal kernels.
2# Public operations use only the flat certificates returned at their boundary.
3import Base
4import stelliferous@0.0.3.0/tensor_access.bend as Access
5import stelliferous@0.0.3.0/tensor_view.bend as Views
6import stelliferous@0.0.3.0/traversal_array.bend as Traversal
7import stelliferous@0.0.3.0/traversal_loop.bend as Loop
8import stelliferous@0.0.3.0/tensor_cursor.bend as Cursor
9import stelliferous@0.0.3.0/proofs/tensor_cursor_witness.bend as CursorWitness
10import stelliferous@0.0.3.0/proofs/traversal_visit_witness.bend as VisitWitness
11import stelliferous@0.0.3.0/proofs/storage_certificate.bend as Certificate
12import stelliferous@0.0.3.0/proofs/storage_tree_model.bend as Tree
13import stelliferous@0.0.3.0/proofs/storage_witness.bend as Witness
14import stelliferous@0.0.3.0/proofs/traversal_witness.bend as TraversalWitness
15import stelliferous@0.0.3.0/proofs/traversal_certificate.bend as TraversalCertificate
16
17def read_index(~Element: Data,-input: Array<Element>,context: Unit,index: U32,evidence: Witness.ArrayWitness<Element,input>) ->
18  TraversalWitness.Sample<Array<Element>,Element,input,Traversal.read_index(~Element,input,context,index)>:
19  TraversalWitness.array_sample(~Element,input,Array.get(Element,input,index),Witness.observed(Element,input,index,evidence))
20
21type CopyCall is Data:
22  CopyCall{fast: Bool,count: Nat,source: Views.View,destination: U32}
23
24def copy_operation(~Element: Data,call: CopyCall,input: Array<Element>,output: Array<Element>) -> Array<Element> & Array<Element>:
25  CopyCall{fast,count,source,destination} = call
26  Access.copy_run(~Element,fast,count,source,destination,input,output)
27
28def combine_operation(~Element: Data,~operation: Element -> Element -> Element,call: CopyCall,input: Array<Element>,output: Array<Element>) -> Array<Element> & Array<Element>:
29  CopyCall{fast,count,source,destination} = call
30  Access.combine_run(~Element,~operation,fast,count,source,destination,input,output)
31
32# A strided operation keeps its owners through each part of a run: the stride
33# steps, the state handed to the cursor, and the cursor step that ends the run.
34# The lemmas are generic in the two element steps and in the evidence that
35# each of them keeps.
36def last_of_run(~Element: Data,+depth: Nat,extent: Nat,stride: U32,rewind: U32,rest: Cursor.Depth1(),-input: Array<Element>,
37  -state: Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Stride>,
38  evidence: TraversalWitness.StateEvidence<Array<Element>,Element,Cursor.Stride,input,depth,state>) ->
39  TraversalWitness.StateEvidence<Array<Element>,Element,Cursor.Cursor,input,depth,Access.last_of_run(~Element,extent,stride,rewind,rest,state)>:
40  match evidence:
41    case TraversalWitness.StateEvidence{output,position,Cursor.Stride{address,step},equation,output_evidence}:
42      %Equal.sym(Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Stride>,state,Traversal.State{input,output,position,Cursor.Stride{address,step}},equation) :
43        TraversalWitness.StateEvidence<Array<Element>,Element,Cursor.Cursor,input,depth,Access.last_of_run(~Element,extent,stride,rewind,rest,_)>
44      TraversalWitness.StateEvidence{output,position,Cursor.Cursor{Cursor.Level{Cursor.Axis{extent,1n,stride,rewind},rest},address},{==},output_evidence}
45
46# A step keeps the evidence of its state.
47def Keeps(~Element: Data,~Context: Data,~step: Traversal.State<&1,&1,Array<Element>,Array<Element>,Context> -> Traversal.State<&1,&1,Array<Element>,Array<Element>,Context>) -> Type:
48  @+depth: Nat -> @-input: Array<Element> -> @-state: Traversal.State<&1,&1,Array<Element>,Array<Element>,Context> -> Witness.ArrayWitness<Element,input> ->
49    TraversalWitness.StateEvidence<Array<Element>,Element,Context,input,depth,state> -> TraversalWitness.StateEvidence<Array<Element>,Element,Context,input,depth,step(state)>
50
51def loop(~Element: Data,~Context: Data,~step: Traversal.State<&1,&1,Array<Element>,Array<Element>,Context> -> Traversal.State<&1,&1,Array<Element>,Array<Element>,Context>,
52  ~keeps: Keeps(~Element,~Context,~step),
53  +depth: Nat,count: Nat,-input: Array<Element>,-state: Traversal.State<&1,&1,Array<Element>,Array<Element>,Context>,+input_evidence: Witness.ArrayWitness<Element,input>,
54  evidence: TraversalWitness.StateEvidence<Array<Element>,Element,Context,input,depth,state>) ->
55  TraversalWitness.StateEvidence<Array<Element>,Element,Context,input,depth,Loop.run(~Traversal.State<&1,&1,Array<Element>,Array<Element>,Context>,~step,count,state)>:
56  match count:
57    case 0n: evidence
58    case 1n+rest:
59      loop(~Element,~Context,~step,~keeps,depth,rest,input,step(state),input_evidence,keeps(depth,input,state,input_evidence,evidence))
60
61def run_axis(~Element: Data,~inside: Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Stride> -> Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Stride>,~last: Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Cursor> -> Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Cursor>,
62  ~inside_keeps: Keeps(~Element,~Cursor.Stride,~inside),
63  ~last_keeps: Keeps(~Element,~Cursor.Cursor,~last),
64  +depth: Nat,remaining: Nat,extent: Nat,+stride: U32,rewind: U32,rest: Cursor.Depth1(),+address: U32,
65  -input: Array<Element>,-output: Array<Element>,position: U32,+input_evidence: Witness.ArrayWitness<Element,input>,
66  output_evidence: Witness.Witness(Element,depth,output)) ->
67  TraversalWitness.StateEvidence<Array<Element>,Element,Cursor.Cursor,input,depth,Access.run_axis(~Element,~inside,~last,remaining,extent,stride,rewind,rest,address,input,output,position)>:
68  match remaining:
69    case 0n:
70      last_keeps(depth,input,Traversal.State{input,output,position,Cursor.Cursor{Cursor.Level{Cursor.Axis{extent,0n,stride,rewind},rest},address}},input_evidence,
71        TraversalWitness.StateEvidence{output,position,Cursor.Cursor{Cursor.Level{Cursor.Axis{extent,0n,stride,rewind},rest},address},{==},output_evidence})
72    case 1n+count:
73      last_keeps(depth,input,
74        Access.last_of_run(~Element,extent,stride,rewind,rest,Loop.run(~Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Stride>,~inside,count,Traversal.State{input,output,position,Cursor.Stride{address,stride}})),
75        input_evidence,
76        last_of_run(~Element,depth,extent,stride,rewind,rest,input,Loop.run(~Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Stride>,~inside,count,Traversal.State{input,output,position,Cursor.Stride{address,stride}}),
77          loop(~Element,~Cursor.Stride,~inside,~inside_keeps,depth,count,input,Traversal.State{input,output,position,Cursor.Stride{address,stride}},input_evidence,
78            TraversalWitness.StateEvidence{output,position,Cursor.Stride{address,stride},{==},output_evidence})))
79
80def run_step(~Element: Data,~inside: Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Stride> -> Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Stride>,~last: Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Cursor> -> Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Cursor>,
81  ~inside_keeps: Keeps(~Element,~Cursor.Stride,~inside),
82  ~last_keeps: Keeps(~Element,~Cursor.Cursor,~last),
83  +depth: Nat,-input: Array<Element>,-state: Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Cursor>,
84  +input_evidence: Witness.ArrayWitness<Element,input>,evidence: TraversalWitness.StateEvidence<Array<Element>,Element,Cursor.Cursor,input,depth,state>) ->
85  TraversalWitness.StateEvidence<Array<Element>,Element,Cursor.Cursor,input,depth,Access.run_step(~Element,~inside,~last,state)>:
86  match evidence:
87    case TraversalWitness.StateEvidence{output,position,Cursor.Cursor{Cursor.Level{Cursor.Axis{extent,remaining,stride,rewind},rest},address},equation,output_evidence}:
88      %Equal.sym(Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Cursor>,state,
89        Traversal.State{input,output,position,Cursor.Cursor{Cursor.Level{Cursor.Axis{extent,remaining,stride,rewind},rest},address}},equation) :
90        TraversalWitness.StateEvidence<Array<Element>,Element,Cursor.Cursor,input,depth,Access.run_step(~Element,~inside,~last,_)>
91      run_axis(~Element,~inside,~last,~inside_keeps,~last_keeps,depth,remaining,extent,stride,rewind,rest,address,input,output,position,input_evidence,output_evidence)
92
93def run_loop(~Element: Data,~inside: Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Stride> -> Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Stride>,~last: Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Cursor> -> Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Cursor>,
94  ~inside_keeps: Keeps(~Element,~Cursor.Stride,~inside),
95  ~last_keeps: Keeps(~Element,~Cursor.Cursor,~last),
96  +depth: Nat,count: Nat,-input: Array<Element>,-state: Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Cursor>,
97  +input_evidence: Witness.ArrayWitness<Element,input>,evidence: TraversalWitness.StateEvidence<Array<Element>,Element,Cursor.Cursor,input,depth,state>) ->
98  TraversalWitness.StateEvidence<Array<Element>,Element,Cursor.Cursor,input,depth,Loop.run(~Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Cursor>,~Access.run_step(~Element,~inside,~last),count,state)>:
99  match count:
100    case 0n: evidence
101    case 1n+rest:
102      run_loop(~Element,~inside,~last,~inside_keeps,~last_keeps,depth,rest,input,Access.run_step(~Element,~inside,~last,state),input_evidence,
103        run_step(~Element,~inside,~last,~inside_keeps,~last_keeps,depth,input,state,input_evidence,evidence))
104
105def last_loop(~Element: Data,~last: Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Cursor> -> Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Cursor>,
106  ~last_keeps: Keeps(~Element,~Cursor.Cursor,~last),
107  +depth: Nat,count: Nat,-input: Array<Element>,-state: Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Cursor>,
108  +input_evidence: Witness.ArrayWitness<Element,input>,evidence: TraversalWitness.StateEvidence<Array<Element>,Element,Cursor.Cursor,input,depth,state>) ->
109  TraversalWitness.StateEvidence<Array<Element>,Element,Cursor.Cursor,input,depth,Loop.run(~Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Cursor>,~last,count,state)>:
110  loop(~Element,~Cursor.Cursor,~last,~last_keeps,depth,count,input,state,input_evidence,evidence)
111
112def stepped(~Element: Data,~last: Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Cursor> -> Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Cursor>,
113  ~last_keeps: Keeps(~Element,~Cursor.Cursor,~last),
114  +depth: Nat,count: Nat,cursor: Cursor.Cursor,destination: U32,-input: Array<Element>,-output: Array<Element>,
115  input_evidence: Witness.ArrayWitness<Element,input>,
116  equation: {output == Tree.pack(Element,Certificate.normalized(Element,depth,Tree.reflect(Element,output))) : Array<Element>}) ->
117  TraversalWitness.ResultEvidence<Array<Element>,Element,input,depth,
118    Traversal.finish(~Array<Element>,~Element,~Cursor.Cursor,Loop.run(~Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Cursor>,~last,count,
119      Traversal.State{input,output,destination,cursor}))>:
120  TraversalCertificate.completed(~Array<Element>,~Element,~Cursor.Cursor,~TraversalWitness.array_evidence(~Element),
121    ~Loop.run(~Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Cursor>,~last),~last_loop(~Element,~last,~last_keeps),
122    count,destination,cursor,input,output,input_evidence,depth,equation)
123
124def guarded(~Element: Data,~inside: Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Stride> -> Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Stride>,~last: Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Cursor> -> Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Cursor>,
125  ~inside_keeps: Keeps(~Element,~Cursor.Stride,~inside),
126  ~last_keeps: Keeps(~Element,~Cursor.Cursor,~last),
127  +depth: Nat,full_run: Bool,whole_runs: Bool,runs: Nat,count: Nat,cursor: Cursor.Cursor,destination: U32,
128  -input: Array<Element>,-output: Array<Element>,input_evidence: Witness.ArrayWitness<Element,input>,
129  equation: {output == Tree.pack(Element,Certificate.normalized(Element,depth,Tree.reflect(Element,output))) : Array<Element>}) ->
130  TraversalWitness.ResultEvidence<Array<Element>,Element,input,depth,Access.run_guarded(~Element,~inside,~last,full_run,whole_runs,runs,count,cursor,destination,input,output)>:
131  match full_run whole_runs:
132    case True{} True{}:
133      TraversalCertificate.completed(~Array<Element>,~Element,~Cursor.Cursor,~TraversalWitness.array_evidence(~Element),
134        ~Loop.run(~Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Cursor>,~Access.run_step(~Element,~inside,~last)),~run_loop(~Element,~inside,~last,~inside_keeps,~last_keeps),
135        runs,destination,cursor,input,output,input_evidence,depth,equation)
136    case True{} False{}: stepped(~Element,~last,~last_keeps,depth,count,cursor,destination,input,output,input_evidence,equation)
137    case False{} whole_runs: stepped(~Element,~last,~last_keeps,depth,count,cursor,destination,input,output,input_evidence,equation)
138
139def remaining_run(~Element: Data,~inside: Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Stride> -> Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Stride>,~last: Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Cursor> -> Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Cursor>,
140  ~inside_keeps: Keeps(~Element,~Cursor.Stride,~inside),
141  ~last_keeps: Keeps(~Element,~Cursor.Cursor,~last),
142  +depth: Nat,remaining: Nat,+extent: Nat,stride: U32,rewind: U32,rest: Cursor.Depth1(),address: U32,+count: Nat,destination: U32,
143  -input: Array<Element>,-output: Array<Element>,input_evidence: Witness.ArrayWitness<Element,input>,
144  equation: {output == Tree.pack(Element,Certificate.normalized(Element,depth,Tree.reflect(Element,output))) : Array<Element>}) ->
145  TraversalWitness.ResultEvidence<Array<Element>,Element,input,depth,Access.run_remaining(~Element,~inside,~last,remaining,extent,stride,rewind,rest,address,count,destination,input,output)>:
146  match remaining:
147    case 0n:
148      stepped(~Element,~last,~last_keeps,depth,count,Cursor.Cursor{Cursor.Level{Cursor.Axis{extent,0n,stride,rewind},rest},address},destination,input,output,input_evidence,equation)
149    case 1n+ +inner_count:
150      guarded(~Element,~inside,~last,~inside_keeps,~last_keeps,depth,Nat.is_eq(extent,1n+inner_count),Nat.is_eq(Nat.mul(Nat.div(count,1n+inner_count),1n+inner_count),count),Nat.div(count,1n+inner_count),count,
151        Cursor.Cursor{Cursor.Level{Cursor.Axis{extent,1n+inner_count,stride,rewind},rest},address},destination,input,output,input_evidence,equation)
152
153def strided(~Element: Data,~inside: Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Stride> -> Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Stride>,~last: Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Cursor> -> Traversal.State<&1,&1,Array<Element>,Array<Element>,Cursor.Cursor>,
154  ~inside_keeps: Keeps(~Element,~Cursor.Stride,~inside),
155  ~last_keeps: Keeps(~Element,~Cursor.Cursor,~last),
156  +depth: Nat,count: Nat,cursor: Cursor.Cursor,destination: U32,-input: Array<Element>,-output: Array<Element>,
157  input_evidence: Witness.ArrayWitness<Element,input>,
158  equation: {output == Tree.pack(Element,Certificate.normalized(Element,depth,Tree.reflect(Element,output))) : Array<Element>}) ->
159  TraversalWitness.ResultEvidence<Array<Element>,Element,input,depth,Access.run_strided(~Element,~inside,~last,count,cursor,destination,input,output)>:
160  Cursor.Cursor{Cursor.Level{Cursor.Axis{extent,remaining,stride,rewind},rest},address} = cursor
161  remaining_run(~Element,~inside,~last,~inside_keeps,~last_keeps,depth,remaining,extent,stride,rewind,rest,address,count,destination,input,output,input_evidence,equation)
162
163def copied_strided(~Element: Data,+depth: Nat,count: Nat,cursor: Cursor.Cursor,destination: U32,-input: Array<Element>,-output: Array<Element>,
164  input_evidence: Witness.ArrayWitness<Element,input>,
165  equation: {output == Tree.pack(Element,Certificate.normalized(Element,depth,Tree.reflect(Element,output))) : Array<Element>}) ->
166  TraversalWitness.ResultEvidence<Array<Element>,Element,input,depth,Access.copy_strided(~Element,count,cursor,destination,input,output)>:
167  strided(~Element,~Traversal.visit_step(~Array<Element>,~Element,~Cursor.Stride,~Cursor.read_stride(~Element)),
168    ~Traversal.visit_step(~Array<Element>,~Element,~Cursor.Cursor,~Cursor.read(~Element)),
169    ~VisitWitness.step(~Array<Element>,~Element,~Cursor.Stride,~TraversalWitness.array_evidence(~Element),~Cursor.read_stride(~Element),~CursorWitness.read_stride(~Element)),
170    ~VisitWitness.step(~Array<Element>,~Element,~Cursor.Cursor,~TraversalWitness.array_evidence(~Element),~Cursor.read(~Element),~CursorWitness.read(~Element)),
171    depth,count,cursor,destination,input,output,input_evidence,equation)
172
173def updated_strided(~Element: Data,~operation: Element -> Element -> Element,+depth: Nat,count: Nat,cursor: Cursor.Cursor,destination: U32,
174  -input: Array<Element>,-output: Array<Element>,input_evidence: Witness.ArrayWitness<Element,input>,
175  equation: {output == Tree.pack(Element,Certificate.normalized(Element,depth,Tree.reflect(Element,output))) : Array<Element>}) ->
176  TraversalWitness.ResultEvidence<Array<Element>,Element,input,depth,Access.update_strided(~Element,~operation,count,cursor,destination,input,output)>:
177  strided(~Element,~Traversal.visit_update_step(~Array<Element>,~Element,~Cursor.Stride,~Cursor.read_stride(~Element),~operation),
178    ~Traversal.visit_update_step(~Array<Element>,~Element,~Cursor.Cursor,~Cursor.read(~Element),~operation),
179    ~VisitWitness.update_step(~Array<Element>,~Element,~Cursor.Stride,~TraversalWitness.array_evidence(~Element),~Cursor.read_stride(~Element),~operation,~CursorWitness.read_stride(~Element)),
180    ~VisitWitness.update_step(~Array<Element>,~Element,~Cursor.Cursor,~TraversalWitness.array_evidence(~Element),~Cursor.read(~Element),~operation,~CursorWitness.read(~Element)),
181    depth,count,cursor,destination,input,output,input_evidence,equation)
182
183type ScatterCall is Data:
184  ScatterCall{count: Nat,target: Views.View,source: U32}
185
186def scatter_operation(~Element: Data,call: ScatterCall,input: Array<Element>,output: Array<Element>) -> Array<Element> & Array<Element>:
187  ScatterCall{count,target,source} = call
188  Access.scatter_run(~Element,count,target,source,input,output)
189
190def scattered(~Element: Data,+depth: Nat,call: ScatterCall,-input: Array<Element>,-output: Array<Element>,input_certificate: Certificate.Certificate<Element,input>,
191  equation: {output == Tree.pack(Element,Certificate.normalized(Element,depth,Tree.reflect(Element,output))) : Array<Element>}) ->
192  TraversalWitness.ResultEvidence<Array<Element>,Element,input,depth,scatter_operation(~Element,call,input,output)>:
193  match call:
194    case ScatterCall{count,target,source}:
195      strided(~Element,~Traversal.spread_step(~Element,~Cursor.Stride,~Cursor.target_stride),~Traversal.spread_step(~Element,~Cursor.Cursor,~Cursor.target),
196        ~VisitWitness.spread_step(~Element,~Cursor.Stride,~Cursor.target_stride),~VisitWitness.spread_step(~Element,~Cursor.Cursor,~Cursor.target),
197        depth,count,Cursor.prepare(target),source,input,output,Certificate.witness(Element,input,input_certificate),equation)
198
199def copied(~Element: Data,+depth: Nat,call: CopyCall,-input: Array<Element>,-output: Array<Element>,input_certificate: Certificate.Certificate<Element,input>,
200  equation: {output == Tree.pack(Element,Certificate.normalized(Element,depth,Tree.reflect(Element,output))) : Array<Element>}) ->
201  TraversalWitness.ResultEvidence<Array<Element>,Element,input,depth,copy_operation(~Element,call,input,output)>:
202  match call:
203    case CopyCall{True{},count,Views.View{axes,offset},destination}:
204      TraversalCertificate.completed(~Array<Element>,~Element,~Traversal.Offsets,~TraversalWitness.array_evidence(~Element),
205        ~Traversal.run(~Array<Element>,~Element,~Traversal.Offsets,~Traversal.source_offset(~Element),~Traversal.destination_offset),
206        ~TraversalWitness.run(~Array<Element>,~Element,~Traversal.Offsets,~TraversalWitness.array_evidence(~Element),~Traversal.source_offset(~Element),~Traversal.destination_offset,~TraversalWitness.offset_read(~Element)),
207        count,0,Traversal.Offsets{offset,destination},input,output,Certificate.witness(Element,input,input_certificate),depth,equation)
208    case CopyCall{False{},count,source,destination}:
209      copied_strided(~Element,depth,count,Cursor.prepare(source),destination,input,output,Certificate.witness(Element,input,input_certificate),equation)
210
211def combined(~Element: Data,~operation: Element -> Element -> Element,+depth: Nat,call: CopyCall,-input: Array<Element>,-output: Array<Element>,
212  input_certificate: Certificate.Certificate<Element,input>,
213  equation: {output == Tree.pack(Element,Certificate.normalized(Element,depth,Tree.reflect(Element,output))) : Array<Element>}) ->
214  TraversalWitness.ResultEvidence<Array<Element>,Element,input,depth,combine_operation(~Element,~operation,call,input,output)>:
215  match call:
216    case CopyCall{True{},count,source,destination}:
217      TraversalCertificate.completed(~Array<Element>,~Element,~Unit,~TraversalWitness.array_evidence(~Element),
218        ~Traversal.update(~Array<Element>,~Element,~Element,~Unit,~Traversal.read_index(~Element),~operation,~Traversal.index),
219        ~TraversalWitness.update(~Array<Element>,~Element,~Element,~Unit,~TraversalWitness.array_evidence(~Element),~Traversal.read_index(~Element),~operation,~Traversal.index,~read_index(~Element)),
220        count,0,Unit{},input,output,Certificate.witness(Element,input,input_certificate),depth,equation)
221    case CopyCall{False{},count,source,destination}:
222      updated_strided(~Element,~operation,depth,count,Cursor.prepare(source),destination,input,output,Certificate.witness(Element,input,input_certificate),equation)
223
224def copy(~Element: Data,fast: Bool,count: Nat,source: Views.View,destination: U32,-input: Array<Element>,-output: Array<Element>,
225  input_certificate: Certificate.Certificate<Element,input>,output_certificate: Certificate.Certificate<Element,output>) ->
226  TraversalCertificate.Certificates<Array<Element>,Element,Certificate.family(~Element),Access.copy_run(~Element,fast,count,source,destination,input,output)>:
227  Certificate.Certificate{+depth,+equation} = input_certificate
228  TraversalCertificate.operation(~Array<Element>,~Element,~CopyCall,~Certificate.family(~Element),~copy_operation(~Element),~copied(~Element),
229    CopyCall{fast,count,source,destination},input,output,Certificate.Certificate{depth,equation},Certificate.Certificate{depth,equation},Certificate.Certificate{depth,equation},output_certificate)
230
231def scatter(~Element: Data,count: Nat,target: Views.View,source: U32,-input: Array<Element>,-output: Array<Element>,
232  input_certificate: Certificate.Certificate<Element,input>,output_certificate: Certificate.Certificate<Element,output>) ->
233  TraversalCertificate.Certificates<Array<Element>,Element,Certificate.family(~Element),Access.scatter_run(~Element,count,target,source,input,output)>:
234  Certificate.Certificate{+depth,+equation} = input_certificate
235  TraversalCertificate.operation(~Array<Element>,~Element,~ScatterCall,~Certificate.family(~Element),~scatter_operation(~Element),~scattered(~Element),
236    ScatterCall{count,target,source},input,output,Certificate.Certificate{depth,equation},Certificate.Certificate{depth,equation},Certificate.Certificate{depth,equation},output_certificate)
237
238def combine(~Element: Data,~operation: Element -> Element -> Element,fast: Bool,count: Nat,source: Views.View,destination: U32,
239  -input: Array<Element>,-output: Array<Element>,input_certificate: Certificate.Certificate<Element,input>,output_certificate: Certificate.Certificate<Element,output>) ->
240  TraversalCertificate.Certificates<Array<Element>,Element,Certificate.family(~Element),Access.combine_run(~Element,~operation,fast,count,source,destination,input,output)>:
241  Certificate.Certificate{+depth,+equation} = input_certificate
242  TraversalCertificate.operation(~Array<Element>,~Element,~CopyCall,~Certificate.family(~Element),~combine_operation(~Element,~operation),~combined(~Element,~operation),
243    CopyCall{fast,count,source,destination},input,output,Certificate.Certificate{depth,equation},Certificate.Certificate{depth,equation},Certificate.Certificate{depth,equation},output_certificate)
244
245# The reduction of the lines of a view: every run reads the input and
246# returns it, so the visit returns its input and writes only its output.
247def ran(~Element: Data,~Accumulator: Data,+axes: Cursor.Levels(),+address: U32,+extent: U32,+stride: U32,+position: U32,
248  -input: Array<Element>,-state: Traversal.State<&1,&2,Array<Element>,Accumulator,Traversal.Strided>,
249  evidence: TraversalWitness.FoldEvidence<Array<Element>,Accumulator,Traversal.Strided,input,state>) ->
250  TraversalWitness.FoldEvidence<Array<Element>,Accumulator,Access.Runs,input,
251    Access.ran(~Element,~Accumulator,axes,address,extent,stride,position,Traversal.finish_fold(~Array<Element>,~Accumulator,~Traversal.Strided,state))>:
252  match evidence:
253    case TraversalWitness.FoldEvidence{accumulator,inner,context,equation}:
254      %Equal.sym(Traversal.State<&1,&2,Array<Element>,Accumulator,Traversal.Strided>,state,Traversal.State{input,accumulator,inner,context},equation) :
255        TraversalWitness.FoldEvidence<Array<Element>,Accumulator,Access.Runs,input,
256          Access.ran(~Element,~Accumulator,axes,address,extent,stride,position,Traversal.finish_fold(~Array<Element>,~Accumulator,~Traversal.Strided,_))>
257      TraversalWitness.FoldEvidence{accumulator,(position + 1 : U32),Access.Runs{Cursor.advance(axes,address),extent,stride},{==}}
258
259def fold_run(~Element: Data,~Accumulator: Data,~operation: Accumulator -> Element -> Accumulator,
260  -input: Array<Element>,-state: Traversal.State<&1,&2,Array<Element>,Accumulator,Access.Runs>,+witness: Witness.ArrayWitness<Element,input>,
261  evidence: TraversalWitness.FoldEvidence<Array<Element>,Accumulator,Access.Runs,input,state>) ->
262  TraversalWitness.FoldEvidence<Array<Element>,Accumulator,Access.Runs,input,Access.fold_run(~Element,~Accumulator,~operation,state)>:
263  match evidence:
264    case TraversalWitness.FoldEvidence{+accumulator,+position,Access.Runs{Cursor.Cursor{+axes,+address},+extent,+stride},equation}:
265      %Equal.sym(Traversal.State<&1,&2,Array<Element>,Accumulator,Access.Runs>,state,
266          Traversal.State{input,accumulator,position,Access.Runs{Cursor.Cursor{axes,address},extent,stride}},equation) :
267        TraversalWitness.FoldEvidence<Array<Element>,Accumulator,Access.Runs,input,Access.fold_run(~Element,~Accumulator,~operation,_)>
268      ran(~Element,~Accumulator,axes,address,extent,stride,position,input,
269        Loop.run(~Traversal.State<&1,&2,Array<Element>,Accumulator,Traversal.Strided>,
270          ~Traversal.fold_round(~Array<Element>,~Element,~Accumulator,~Traversal.Strided,~Traversal.strided(~Element),~operation),Nat.div(U32.to_nat(extent),8n),
271          Loop.run(~Traversal.State<&1,&2,Array<Element>,Accumulator,Traversal.Strided>,
272            ~Traversal.fold_step(~Array<Element>,~Element,~Accumulator,~Traversal.Strided,~Traversal.strided(~Element),~operation),Nat.mod(U32.to_nat(extent),8n),
273            Traversal.State{input,accumulator,0,Traversal.Strided{address,stride}})),
274        TraversalWitness.rounds(~Array<Element>,~Element,~Accumulator,~Traversal.Strided,~TraversalWitness.array_evidence(~Element),~Traversal.strided(~Element),~operation,
275          ~TraversalWitness.strided_read(~Element),U32.to_nat(extent),input,0,Traversal.Strided{address,stride},accumulator,witness))
276
277def runs_done(~Element: Data,~Accumulator: Data,~operation: Accumulator -> Element -> Accumulator,count: Nat,
278  -input: Array<Element>,-state: Traversal.State<&1,&2,Array<Element>,Accumulator,Access.Runs>,+witness: Witness.ArrayWitness<Element,input>,
279  evidence: TraversalWitness.FoldEvidence<Array<Element>,Accumulator,Access.Runs,input,state>) ->
280  TraversalWitness.FoldEvidence<Array<Element>,Accumulator,Access.Runs,input,
281    Loop.run(~Traversal.State<&1,&2,Array<Element>,Accumulator,Access.Runs>,~Access.fold_run(~Element,~Accumulator,~operation),count,state)>:
282  match count:
283    case 0n: evidence
284    case 1n+rest:
285      runs_done(~Element,~Accumulator,~operation,rest,input,Access.fold_run(~Element,~Accumulator,~operation,state),witness,
286        fold_run(~Element,~Accumulator,~operation,input,state,witness,evidence))
287
288def folded_line(~Element: Data,~Accumulator: Data,~finish: Accumulator -> Element,+runs: Nat,+initial: Accumulator,
289  -input: Array<Element>,-state: Traversal.State<&1,&2,Array<Element>,Accumulator,Access.Runs>,
290  evidence: TraversalWitness.FoldEvidence<Array<Element>,Accumulator,Access.Runs,input,state>) ->
291  VisitWitness.Sample<Array<Element>,Element,Access.Lines<Accumulator>,input,Access.folded_line(~Element,~Accumulator,~finish,runs,initial,state)>:
292  match evidence:
293    case TraversalWitness.FoldEvidence{accumulator,position,Access.Runs{cursor,extent,stride},equation}:
294      %Equal.sym(Traversal.State<&1,&2,Array<Element>,Accumulator,Access.Runs>,state,Traversal.State{input,accumulator,position,Access.Runs{cursor,extent,stride}},equation) :
295        VisitWitness.Sample<Array<Element>,Element,Access.Lines<Accumulator>,input,Access.folded_line(~Element,~Accumulator,~finish,runs,initial,_)>
296      VisitWitness.Sample{Access.Lines{cursor,runs,extent,stride,initial},finish(accumulator),{==}}
297
298def fold_line(~Element: Data,~Accumulator: Data,~operation: Accumulator -> Element -> Accumulator,~finish: Accumulator -> Element,
299  -input: Array<Element>,context: Access.Lines<Accumulator>,evidence: Witness.ArrayWitness<Element,input>) ->
300  VisitWitness.Sample<Array<Element>,Element,Access.Lines<Accumulator>,input,Access.fold_line(~Element,~Accumulator,~operation,~finish,input,context)>:
301  Access.Lines{+cursor,+runs,+extent,+stride,+initial} = context
302  folded_line(~Element,~Accumulator,~finish,runs,initial,input,
303    Loop.run(~Traversal.State<&1,&2,Array<Element>,Accumulator,Access.Runs>,~Access.fold_run(~Element,~Accumulator,~operation),runs,
304      Traversal.State{input,initial,0,Access.Runs{cursor,extent,stride}}),
305    runs_done(~Element,~Accumulator,~operation,runs,input,Traversal.State{input,initial,0,Access.Runs{cursor,extent,stride}},evidence,
306      TraversalWitness.FoldEvidence{initial,0,Access.Runs{cursor,extent,stride},{==}}))
307
308type LinesCall<-Accumulator: Data> is Data:
309  LinesCall{count: Nat,view: Views.View,runs: Nat,extent: U32,stride: U32,initial: Accumulator}
310
311def lines_operation(~Element: Data,~Accumulator: Data,~operation: Accumulator -> Element -> Accumulator,~finish: Accumulator -> Element,
312  call: LinesCall<Accumulator>,input: Array<Element>,output: Array<Element>) -> Array<Element> & Array<Element>:
313  LinesCall{count,view,runs,extent,stride,initial} = call
314  Access.reduce_lines(~Element,~Accumulator,~operation,~finish,count,view,runs,extent,stride,initial,input,output)
315
316def lined(~Element: Data,~Accumulator: Data,~operation: Accumulator -> Element -> Accumulator,~finish: Accumulator -> Element,
317  +depth: Nat,call: LinesCall<Accumulator>,-input: Array<Element>,-output: Array<Element>,input_certificate: Certificate.Certificate<Element,input>,
318  equation: {output == Tree.pack(Element,Certificate.normalized(Element,depth,Tree.reflect(Element,output))) : Array<Element>}) ->
319  TraversalWitness.ResultEvidence<Array<Element>,Element,input,depth,lines_operation(~Element,~Accumulator,~operation,~finish,call,input,output)>:
320  match call:
321    case LinesCall{count,view,runs,extent,stride,initial}:
322      TraversalCertificate.completed(~Array<Element>,~Element,~Access.Lines<Accumulator>,~TraversalWitness.array_evidence(~Element),
323        ~Traversal.visit(~Array<Element>,~Element,~Access.Lines<Accumulator>,~Access.fold_line(~Element,~Accumulator,~operation,~finish)),
324        ~VisitWitness.visit(~Array<Element>,~Element,~Access.Lines<Accumulator>,~TraversalWitness.array_evidence(~Element),
325          ~Access.fold_line(~Element,~Accumulator,~operation,~finish),~fold_line(~Element,~Accumulator,~operation,~finish)),
326        count,0,Access.Lines{Cursor.prepare(view),runs,extent,stride,initial},input,output,Certificate.witness(Element,input,input_certificate),depth,equation)
327
328def lines(~Element: Data,~Accumulator: Data,~operation: Accumulator -> Element -> Accumulator,~finish: Accumulator -> Element,
329  count: Nat,view: Views.View,runs: Nat,extent: U32,stride: U32,initial: Accumulator,-input: Array<Element>,-output: Array<Element>,
330  input_certificate: Certificate.Certificate<Element,input>,output_certificate: Certificate.Certificate<Element,output>) ->
331  TraversalCertificate.Certificates<Array<Element>,Element,Certificate.family(~Element),
332    Access.reduce_lines(~Element,~Accumulator,~operation,~finish,count,view,runs,extent,stride,initial,input,output)>:
333  Certificate.Certificate{+depth,+equation} = input_certificate
334  TraversalCertificate.operation(~Array<Element>,~Element,~LinesCall<Accumulator>,~Certificate.family(~Element),
335    ~lines_operation(~Element,~Accumulator,~operation,~finish),~lined(~Element,~Accumulator,~operation,~finish),
336    LinesCall{count,view,runs,extent,stride,initial},input,output,Certificate.Certificate{depth,equation},Certificate.Certificate{depth,equation},Certificate.Certificate{depth,equation},output_certificate)
337
338def window_read_sample(~Element: Data,+pad: Element,valid: Bool,-input: Array<Element>,+index: U32,
339  evidence: Witness.ArrayWitness<Element,input>) ->
340  TraversalWitness.Sample<Array<Element>,Element,input,Access.window_read(~Element,pad,valid,input,index)>:
341  match valid:
342    case False{}: TraversalWitness.Sample{pad,{==}}
343    case True{}: TraversalWitness.array_sample(~Element,input,Array.get(Element,input,index),Witness.observed(Element,input,index,evidence))
344
345# The one-axis window reduction: every sample is an element of the input or
346# the pad, so the sweep returns its input and writes only its output.
347def read_line_sample(~Element: Data,-input: Array<Element>,line: Access.Line<Element>,position: U32,
348  evidence: Witness.ArrayWitness<Element,input>) ->
349  TraversalWitness.Sample<Array<Element>,Element,input,Access.read_line(~Element,input,line,position)>:
350  Access.Line{+base,+first,+extent,+step,+padding,+pad} = line
351  +coordinate = (first + position - padding : U32)
352  window_read_sample(~Element,pad,U32.is_lt(coordinate,extent),input,(base + coordinate * step : U32),evidence)
353
354def line_sample(~Element: Data,-input: Array<Element>,
355  -state: Traversal.State<&1,&2,Array<Element>,Element,Access.Line<Element>>,
356  evidence: TraversalWitness.FoldEvidence<Array<Element>,Element,Access.Line<Element>,input,state>) ->
357  TraversalWitness.Sample<Array<Element>,Element,input,Traversal.finish_fold(~Array<Element>,~Element,~Access.Line<Element>,state)>:
358  match evidence:
359    case TraversalWitness.FoldEvidence{accumulator,position,context,equation}:
360      %Equal.sym(Traversal.State<&1,&2,Array<Element>,Element,Access.Line<Element>>,state,Traversal.State{input,accumulator,position,context},equation) :
361        TraversalWitness.Sample<Array<Element>,Element,input,Traversal.finish_fold(~Array<Element>,~Element,~Access.Line<Element>,_)>
362      TraversalWitness.Sample{accumulator,{==}}
363
364def swept_sample(~Element: Data,~operation: Element -> Element -> Element,-input: Array<Element>,context: Access.SweepContext<Element>,position: U32,
365  evidence: Witness.ArrayWitness<Element,input>) ->
366  TraversalWitness.Sample<Array<Element>,Element,input,Access.read_swept(~Element,~operation,input,context,position)>:
367  Access.SweepContext{+sweep,+pad} = context
368  Access.Sweep{extent,step,+kernel,stride,padding,out_extent,origin} = sweep
369  +position = position
370  line_sample(~Element,input,
371    Loop.run(~Traversal.State<&1,&2,Array<Element>,Element,Access.Line<Element>>,
372      ~Traversal.fold_step(~Array<Element>,~Element,~Element,~Access.Line<Element>,~Access.read_line(~Element),~operation),
373      U32.to_nat(kernel),Traversal.State{input,pad,0,Access.line_at(~Element,sweep,pad,position)}),
374    TraversalWitness.fold_run(~Array<Element>,~Element,~Element,~Access.Line<Element>,~TraversalWitness.array_evidence(~Element),~Access.read_line(~Element),~operation,
375      ~read_line_sample(~Element),U32.to_nat(kernel),input,Traversal.State{input,pad,0,Access.line_at(~Element,sweep,pad,position)},evidence,
376      TraversalWitness.FoldEvidence{pad,0,Access.line_at(~Element,sweep,pad,position),{==}}))
377
378type SweepCall<-Element: Data> is Data:
379  SweepCall{count: Nat,context: Access.SweepContext<Element>}
380
381def sweep_operation(~Element: Data,~operation: Element -> Element -> Element,call: SweepCall<Element>,input: Array<Element>,output: Array<Element>) ->
382  Array<Element> & Array<Element>:
383  SweepCall{count,context} = call
384  Access.sweep_run(~Element,~operation,count,context,input,output)
385
386def swept(~Element: Data,~operation: Element -> Element -> Element,+depth: Nat,call: SweepCall<Element>,-input: Array<Element>,-output: Array<Element>,
387  input_certificate: Certificate.Certificate<Element,input>,
388  equation: {output == Tree.pack(Element,Certificate.normalized(Element,depth,Tree.reflect(Element,output))) : Array<Element>}) ->
389  TraversalWitness.ResultEvidence<Array<Element>,Element,input,depth,sweep_operation(~Element,~operation,call,input,output)>:
390  match call:
391    case SweepCall{count,context}:
392      TraversalCertificate.completed(~Array<Element>,~Element,~Access.SweepContext<Element>,~TraversalWitness.array_evidence(~Element),
393        ~Traversal.run(~Array<Element>,~Element,~Access.SweepContext<Element>,~Access.read_swept(~Element,~operation),~Access.swept_index(~Element)),
394        ~TraversalWitness.run(~Array<Element>,~Element,~Access.SweepContext<Element>,~TraversalWitness.array_evidence(~Element),~Access.read_swept(~Element,~operation),
395          ~Access.swept_index(~Element),~swept_sample(~Element,~operation)),
396        count,0,context,input,output,Certificate.witness(Element,input,input_certificate),depth,equation)
397
398def sweep(~Element: Data,~operation: Element -> Element -> Element,count: Nat,context: Access.SweepContext<Element>,-input: Array<Element>,-output: Array<Element>,
399  input_certificate: Certificate.Certificate<Element,input>,output_certificate: Certificate.Certificate<Element,output>) ->
400  TraversalCertificate.Certificates<Array<Element>,Element,Certificate.family(~Element),Access.sweep_run(~Element,~operation,count,context,input,output)>:
401  Certificate.Certificate{+depth,+equation} = input_certificate
402  TraversalCertificate.operation(~Array<Element>,~Element,~SweepCall<Element>,~Certificate.family(~Element),~sweep_operation(~Element,~operation),~swept(~Element,~operation),
403    SweepCall{count,context},input,output,Certificate.Certificate{depth,equation},Certificate.Certificate{depth,equation},Certificate.Certificate{depth,equation},output_certificate)