Rename ChainStep -> ActionEvaluation and ChainEvent -> ChainStep

theories/Blockchain.v

@@ -430,16 +430,16 @@ Proof.
   solve_proper.
 Qed.
 
-Section Step.
 Local Open Scope Z.
-(* Next we define a single step. It specifies how an external action
-changes an environment and which external actions to execute after it. *)
-(* todo: handle deploy/call failures. We should still transfer gas and allow this
-to be recorded. *)
-Inductive ChainStep :
+(* Next we define how actions are executed. It specifies how an action
+changes an environment and which external actions to execute after it.
+Note that there can be multiple ways to execute an action. For example, if
+the action says to deploy a contract, the implementation is responsible for
+selecting which address the new contract should get. *)
+Inductive ActionEvaluation :
   Environment -> Action ->
   Environment -> list Action -> Type :=
-  | step_transfer :
+  | eval_transfer :
       forall {pre : Environment}
              {act : Action}
              {new_env : Environment}
@@ -449,8 +449,8 @@ Inductive ChainStep :
         address_is_contract to = false ->
         act = build_act from (act_transfer to amount) ->
         EnvironmentEquiv new_env (transfer_balance from to amount pre) ->
-        ChainStep pre act new_env []
-  | step_deploy :
+        ActionEvaluation pre act new_env []
+  | eval_deploy :
       forall {pre : Environment}
              {act : Action}
              {new_env : Environment}
@@ -471,8 +471,8 @@ Inductive ChainStep :
       EnvironmentEquiv
         new_env
         (set_contract_state to state (add_contract to wc (transfer_balance from to amount pre))) ->
-      ChainStep pre act new_env []
-  | step_call :
+      ActionEvaluation pre act new_env []
+  | eval_call :
       forall {pre : Environment}
              {act : Action}
              {new_env : Environment}
@@ -501,54 +501,54 @@ Inductive ChainStep :
       EnvironmentEquiv
         new_env
         (set_contract_state to new_state (transfer_balance from to amount pre)) ->
-      ChainStep pre act new_env new_acts.
+      ActionEvaluation pre act new_env new_acts.
 
 Section Accessors.
 Context {pre : Environment} {act : Action}
         {post : Environment} {new_acts : list Action}
-        (step : ChainStep pre act post new_acts).
+        (eval : ActionEvaluation pre act post new_acts).
 
-Definition step_from : Address :=
-  match step with
-  | step_transfer from _ _ _ _ _ _
-  | step_deploy from _ _ _ _ _ _ _ _ _ _ _
-  | step_call from _ _ _ _ _ _ _ _ _ _ _ _ _ _ => from
+Definition eval_from : Address :=
+  match eval with
+  | eval_transfer from _ _ _ _ _ _
+  | eval_deploy from _ _ _ _ _ _ _ _ _ _ _
+  | eval_call from _ _ _ _ _ _ _ _ _ _ _ _ _ _ => from
   end.
 
-Definition step_to : Address :=
-  match step with
-  | step_transfer _ to _ _ _ _ _
-  | step_deploy _ to _ _ _ _ _ _ _ _ _ _
-  | step_call _ to _ _ _ _ _ _ _ _ _ _ _ _ _ => to
+Definition eval_to : Address :=
+  match eval with
+  | eval_transfer _ to _ _ _ _ _
+  | eval_deploy _ to _ _ _ _ _ _ _ _ _ _
+  | eval_call _ to _ _ _ _ _ _ _ _ _ _ _ _ _ => to
   end.
 
-Definition step_amount : Amount :=
-  match step with
-  | step_transfer _ _ amount _ _ _ _
-  | step_deploy _ _ amount _ _ _ _ _ _ _ _ _
-  | step_call _ _ amount _ _ _ _ _ _ _ _ _ _ _ _ => amount
+Definition eval_amount : Amount :=
+  match eval with
+  | eval_transfer _ _ amount _ _ _ _
+  | eval_deploy _ _ amount _ _ _ _ _ _ _ _ _
+  | eval_call _ _ amount _ _ _ _ _ _ _ _ _ _ _ _ => amount
   end.
 End Accessors.
 
 Section Theories.
 Context {pre : Environment} {act : Action}
         {post : Environment} {new_acts : list Action}
-        (step : ChainStep pre act post new_acts).
+        (eval : ActionEvaluation pre act post new_acts).
 
 Lemma account_balance_post (addr : Address) :
   account_balance post addr =
   account_balance pre addr
-  + (if (addr =? step_to step)%address then step_amount step else 0)
-  - (if (addr =? step_from step)%address then step_amount step else 0).
+  + (if (addr =? eval_to eval)%address then eval_amount eval else 0)
+  - (if (addr =? eval_from eval)%address then eval_amount eval else 0).
 Proof.
-  destruct step; cbn; rewrite_environment_equiv; cbn;
+  destruct eval; cbn; rewrite_environment_equiv; cbn;
     unfold add_balance; destruct_address_eq; lia.
 Qed.
 
 Lemma account_balance_post_to :
-  step_from step <> step_to step ->
-  account_balance post (step_to step) =
-  account_balance pre (step_to step) + step_amount step.
+  eval_from eval <> eval_to eval ->
+  account_balance post (eval_to eval) =
+  account_balance pre (eval_to eval) + eval_amount eval.
 Proof.
   intros neq.
   rewrite account_balance_post.
@@ -557,9 +557,9 @@ Proof.
 Qed.
 
 Lemma account_balance_post_from :
-  step_from step <> step_to step ->
-  account_balance post (step_from step) =
-  account_balance pre (step_from step) - step_amount step.
+  eval_from eval <> eval_to eval ->
+  account_balance post (eval_from eval) =
+  account_balance pre (eval_from eval) - eval_amount eval.
 Proof.
   intros neq.
   rewrite account_balance_post.
@@ -568,8 +568,8 @@ Proof.
 Qed.
 
 Lemma account_balance_post_irrelevant (addr : Address) :
-  addr <> step_from step ->
-  addr <> step_to step ->
+  addr <> eval_from eval ->
+  addr <> eval_to eval ->
   account_balance post addr = account_balance pre addr.
 Proof.
   intros neq_from neq_to.
@@ -578,20 +578,19 @@ Proof.
   lia.
 Qed.
 
-Lemma block_header_post_step : block_header post = block_header pre.
-Proof. destruct step; rewrite_environment_equiv; auto. Qed.
+Lemma block_header_post_action : block_header post = block_header pre.
+Proof. destruct eval; rewrite_environment_equiv; auto. Qed.
 
 Lemma contracts_post_pre_none contract :
   env_contracts post contract = None ->
   env_contracts pre contract = None.
 Proof.
   intros H.
-  destruct step; rewrite_environment_equiv; auto.
+  destruct eval; rewrite_environment_equiv; auto.
   cbn in *.
   destruct_address_eq; congruence.
 Qed.
 End Theories.
-End Step.
 
 Section Trace.
 Definition add_new_block
@@ -606,6 +605,7 @@ Definition add_new_block
 
 (* Todo: this should just be a computation. But I still do not *)
 (* know exactly what the best way of working with reflect is *)
+Local Open Scope nat.
 Definition IsValidNextBlock (new old : BlockHeader) : Prop :=
   block_height new = S (block_height old) /\
   slot_number new > slot_number old /\
@@ -621,8 +621,8 @@ Record ChainState :=
     chain_state_queue : list Action;
   }.
 
-Inductive ChainEvent : ChainState -> ChainState -> Type :=
-| evt_block :
+Inductive ChainStep : ChainState -> ChainState -> Type :=
+| step_block :
     forall {prev : ChainState}
            {header : BlockHeader}
            {baker : Address}
@@ -633,22 +633,22 @@ Inductive ChainEvent : ChainState -> ChainState -> Type :=
       EnvironmentEquiv
         next
         (add_new_block header baker prev) ->
-      ChainEvent prev next
-| evt_step :
+      ChainStep prev next
+| step_action :
     forall {prev : ChainState}
            {act : Action}
            {acts : list Action}
            {next : ChainState}
            {new_acts : list Action},
       chain_state_queue prev = act :: acts ->
-      ChainStep prev act next new_acts ->
+      ActionEvaluation prev act next new_acts ->
       chain_state_queue next = new_acts ++ acts ->
-      ChainEvent prev next
-  | evt_permute :
-      forall {prev new : ChainState},
-        chain_state_env prev = chain_state_env new ->
-        Permutation (chain_state_queue prev) (chain_state_queue new) ->
-        ChainEvent prev new.
+      ChainStep prev next
+| step_permute :
+    forall {prev new : ChainState},
+      chain_state_env prev = chain_state_env new ->
+      Permutation (chain_state_queue prev) (chain_state_queue new) ->
+      ChainStep prev new.
 
 Definition empty_state : ChainState :=
   {| chain_state_env :=
@@ -665,7 +665,7 @@ Definition empty_state : ChainState :=
 (* The ChainTrace captures that there is a valid execution where,
 starting from one environment and queue of actions, we end up in a
 different environment and queue of actions. *)
-Definition ChainTrace := ChainedList ChainState ChainEvent.
+Definition ChainTrace := ChainedList ChainState ChainStep.
 
 (* Additionally, a state is reachable if there is a trace ending in this trace. *)
 Definition reachable (state : ChainState) : Prop :=
@@ -674,8 +674,8 @@ Definition reachable (state : ChainState) : Prop :=
 (* We define a transaction as a "fully specified" action, recording all info. For
 example, a transaction contains the contract address that was created when a contract
 is deployed. This is more about bridging the gap between our definitions and what
-a normal blockchain is. Each step corresponds to a transaction and we can go from a
-trace to a list of transactions. *)
+a normal blockchain is. Each evaluation of an action in the blockchain corresponds to
+a transaction, so we can go from a trace to a list of transactions. *)
 Inductive TxBody :=
   | tx_empty
   | tx_deploy (wc : WeakContract) (setup : OakValue)
@@ -689,23 +689,23 @@ Record Tx :=
       tx_body : TxBody;
   }.
 
-Definition step_tx {pre : Environment} {act : Action}
+Definition eval_tx {pre : Environment} {act : Action}
                    {post : Environment} {new_acts : list Action}
-                   (step : ChainStep pre act post new_acts) : Tx :=
+                   (step : ActionEvaluation pre act post new_acts) : Tx :=
   match step with
-  | step_transfer from to amount _ _ _ _ =>
+  | eval_transfer from to amount _ _ _ _ =>
     build_tx from to amount tx_empty
-  | step_deploy from to amount wc setup _ _ _ _ _ _ _ =>
+  | eval_deploy from to amount wc setup _ _ _ _ _ _ _ =>
     build_tx from to amount (tx_deploy wc setup)
-  | step_call from to amount _ msg _ _ _ _ _ _ _ _ _ _ =>
+  | eval_call from to amount _ msg _ _ _ _ _ _ _ _ _ _ =>
     build_tx from to amount (tx_call msg)
   end.
 
 Fixpoint trace_txs {from to : ChainState} (trace : ChainTrace from to) : list Tx :=
   match trace with
-  | snoc trace' evt =>
-    match evt with
-    | evt_step _ step _ => step_tx step :: trace_txs trace'
+  | snoc trace' step =>
+    match step with
+    | step_action _ eval _ => eval_tx eval :: trace_txs trace'
     | _ => trace_txs trace'
     end
   | _ => []
@@ -726,9 +726,9 @@ Definition outgoing_txs
 Fixpoint blocks_baked {from to : ChainState}
          (trace : ChainTrace from to) (addr : Address) : list nat :=
   match trace with
-  | snoc trace' evt =>
-    match evt with
-    | @evt_block _ header baker _ _ _ _ _ =>
+  | snoc trace' step =>
+    match step with
+    | @step_block _ header baker _ _ _ _ _ =>
       if (baker =? addr)%address
       then block_height header :: blocks_baked trace' addr
       else blocks_baked trace' addr
@@ -738,18 +738,18 @@ Fixpoint blocks_baked {from to : ChainState}
   end.
 
 Section Theories.
-Ltac destruct_chain_event :=
+Ltac destruct_chain_step :=
   match goal with
-  | [evt: ChainEvent _ _ |- _] =>
-    destruct evt as
+  | [step: ChainStep _ _ |- _] =>
+    destruct step as
         [prev header baker next queue_prev valid_header acts_from_accs env_eq|
          prev act acts next new_acts queue_prev step queue_new|
          prev new prev_new perm]
   end.
 
-Ltac destruct_chain_step :=
+Ltac destruct_action_eval :=
   match goal with
-  | [step: ChainStep _ _ _ _ |- _] => destruct step
+  | [eval: ActionEvaluation _ _ _ _ |- _] => destruct eval
   end.
 
 Lemma contract_addr_format {to} (addr : Address) (wc : WeakContract) :
@@ -761,9 +761,9 @@ Proof.
   remember empty_state eqn:eq.
   induction trace; rewrite eq in *; clear eq.
   - cbn in *; congruence.
-  - destruct_chain_event.
+  - destruct_chain_step.
     + rewrite_environment_equiv; cbn in *; auto.
-    + destruct_chain_step; rewrite_environment_equiv; cbn in *; destruct_address_eq; subst; auto.
+    + destruct_action_eval; rewrite_environment_equiv; cbn in *; destruct_address_eq; subst; auto.
     + intuition.
 Qed.
 
@@ -791,7 +791,7 @@ Proof.
   remember empty_state eqn:eq.
   induction trace;
     intros undeployed; rewrite eq in *; clear eq; cbn; auto.
-  destruct_chain_event; [|destruct_chain_step|];
+  destruct_chain_step; [|destruct_action_eval|];
     try rewrite_environment_equiv;
     repeat
       match goal with
@@ -833,7 +833,7 @@ Proof.
   intros is_contract undeployed.
   remember empty_state eqn:eq.
   induction trace; cbn; auto.
-  destruct_chain_event.
+  destruct_chain_step.
   - (* New block *)
     rewrite_environment_equiv; auto.
   - (* In these steps we will use that the queue did not contain txs to the contract. *)
@@ -850,7 +850,7 @@ Proof.
       | [H: chain_state_queue _ = _ |- _] => rewrite H in *; clear H
       end.
     inversion_clear Hqueue.
-    destruct_chain_step; rewrite_environment_equiv;
+    destruct_action_eval; rewrite_environment_equiv;
       subst;
       cbn in *;
       destruct_address_eq;
@@ -869,10 +869,10 @@ Proof.
   intros is_contract undeployed.
   remember empty_state eqn:eq.
   induction trace; cbn; auto.
-  destruct_chain_event.
+  destruct_chain_step.
   - (* New block *)
     rewrite_environment_equiv; auto.
-  - destruct_chain_step; rewrite_environment_equiv;
+  - destruct_action_eval; rewrite_environment_equiv;
       cbn in *;
       destruct_address_eq; auto; subst; congruence.
   - match goal with
@@ -889,7 +889,7 @@ Lemma account_balance_trace state (trace : ChainTrace empty_state state) addr :
 Proof.
   unfold incoming_txs, outgoing_txs.
   remember empty_state as from_state.
-  induction trace; [|destruct_chain_event].
+  induction trace; [|destruct_chain_step].
   - subst. cbn. lia.
   - (* Block *)
     rewrite_environment_equiv.
@@ -899,7 +899,7 @@ Proof.
     destruct_address_eq; subst; cbn; lia.
   - (* Step *)
     cbn.
-    destruct_chain_step; cbn; rewrite_environment_equiv; cbn.
+    destruct_action_eval; cbn; rewrite_environment_equiv; cbn.
     all: unfold add_balance; rewrite IHtrace by auto.
     all: destruct_address_eq; cbn; lia.
   - cbn.
@@ -942,23 +942,18 @@ Arguments build_contract {_ _ _ _ _ _ _}.
 Arguments ContractInterface {_} _ _.
 Arguments build_contract_interface {_ _ _ _}.
 
-Ltac destruct_chain_event :=
+Ltac destruct_chain_step :=
   match goal with
-  | [evt: ChainEvent _ _ |- _] =>
-    destruct evt as
+  | [step: ChainStep _ _ |- _] =>
+    destruct step as
         [prev header baker next queue_prev valid_header acts_from_accs env_eq|
          prev act acts next new_acts queue_prev step queue_new|
          prev new prev_new perm]
   end.
 
-Ltac destruct_chain_step :=
-  match goal with
-  | [step: ChainStep _ _ _ _ |- _] => destruct step
-  end.
-
-Ltac invert_chain_step :=
+Ltac destruct_action_eval :=
   match goal with
-  | [step: ChainStep _ _ _ _ |- _] => inversion step
+  | [eval: ActionEvaluation _ _ _ _ |- _] => destruct eval
   end.
 
 Ltac rewrite_environment_equiv :=

theories/Circulation.v

@@ -15,7 +15,7 @@ Local Open Scope Z.
 Definition circulation (chain : Chain) :=
   sumZ (account_balance chain) (elements Address).
 
-(* We then prove that over any single step, the circulation is preserved.
+(* We then prove that over any single action, the circulation is preserved.
 The idea behind this proof is that addrs contain from and to so
 we can move them to the beginning of the sum and it easily follows that
 the sum of their balances is the same as before. For the rest of the
@@ -32,13 +32,13 @@ Proof.
   intuition.
 Qed.
 
-Lemma step_from_to_same
+Lemma eval_action_from_to_same
       {pre : Environment}
       {act : Action}
       {post : Environment}
       {new_acts : list Action}
-      (step : ChainStep pre act post new_acts) :
-  step_from step = step_to step ->
+      (eval : ActionEvaluation pre act post new_acts) :
+  eval_from eval = eval_to eval ->
   circulation post = circulation pre.
 Proof.
   intros from_eq_to.
@@ -46,46 +46,46 @@ Proof.
   induction (elements Address) as [| x xs IH].
   - reflexivity.
   - cbn in *.
-    rewrite IH, (account_balance_post step), from_eq_to.
+    rewrite IH, (account_balance_post eval), from_eq_to.
     lia.
 Qed.
 
-Hint Resolve step_from_to_same : core.
+Hint Resolve eval_action_from_to_same : core.
 
-Lemma step_circulation_unchanged
+Lemma eval_action_circulation_unchanged
       {pre : Environment}
       {act : Action}
       {post : Environment}
       {new_acts : list Action} :
-  ChainStep pre act post new_acts ->
+  ActionEvaluation pre act post new_acts ->
   circulation post = circulation pre.
 Proof.
-  intros step.
-  destruct (address_eqb_spec (step_from step) (step_to step))
+  intros eval.
+  destruct (address_eqb_spec (eval_from eval) (eval_to eval))
     as [from_eq_to | from_neq_to]; eauto.
   destruct (address_reorganize from_neq_to) as [suf perm].
   apply Permutation_sym in perm.
   unfold circulation.
   rewrite 2!(sumZ_permutation perm).
   cbn.
-  rewrite (account_balance_post_to step from_neq_to).
-  rewrite (account_balance_post_from step from_neq_to).
+  rewrite (account_balance_post_to eval from_neq_to).
+  rewrite (account_balance_post_from eval from_neq_to).
   enough (sumZ (account_balance pre) suf = sumZ (account_balance post) suf) by lia.
 
   pose proof (Permutation_NoDup perm) as perm_set.
-  assert (from_not_in_suf: ~In (step_from step) suf).
-  { apply (in_NoDup_app _ [step_from step; step_to step] _); intuition. }
-  assert (to_not_in_suf: ~In (step_to step) suf).
-  { apply (in_NoDup_app _ [step_from step; step_to step] _); intuition. }
+  assert (from_not_in_suf: ~In (eval_from eval) suf).
+  { apply (in_NoDup_app _ [eval_from eval; eval_to eval] _); intuition. }
+  assert (to_not_in_suf: ~In (eval_to eval) suf).
+  { apply (in_NoDup_app _ [eval_from eval; eval_to eval] _); intuition. }
 
   clear perm perm_set.
-  pose proof (account_balance_post_irrelevant step) as balance_irrel.
+  pose proof (account_balance_post_irrelevant eval) as balance_irrel.
   induction suf as [| x xs IH]; auto.
   cbn in *.
   rewrite IH, balance_irrel; auto.
 Qed.
 
-Hint Resolve step_circulation_unchanged : core.
+Hint Resolve eval_action_circulation_unchanged : core.
 
 Instance circulation_proper :
   Proper (ChainEquiv ==> eq) circulation.
@@ -129,23 +129,23 @@ Proof.
   lia.
 Qed.
 
-Lemma event_circulation {prev next} (evt : ChainEvent prev next) :
+Lemma step_circulation {prev next} (step : ChainStep prev next) :
   circulation next =
-  match evt with
-  | evt_block _ _ _ _ =>
+  match step with
+  | step_block _ _ _ _ =>
     circulation prev + compute_block_reward (block_height (block_header next))
   | _ => circulation prev
   end%Z.
 Proof.
-  destruct evt;
+  destruct step;
     repeat
       match goal with
       | [H: EnvironmentEquiv _ _ |- _] => rewrite H in *; clear H
       end.
   - (* New block *)
     now rewrite circulation_add_new_block.
-  - (* New step *)
-    erewrite step_circulation_unchanged; eauto.
+  - (* New action *)
+    erewrite eval_action_circulation_unchanged; eauto.
   - (* Permute queue *)
     intuition.
 Qed.
@@ -161,7 +161,7 @@ Proof.
   induction trace as [| from mid to xs IH x]; rewrite eq in *; clear eq.
   - unfold circulation.
     induction (elements Address); auto.
-  - rewrite (event_circulation x).
+  - rewrite (step_circulation x).
     destruct x.
     + rewrite_environment_equiv.
       cbn.
@@ -170,7 +170,7 @@ Proof.
       | [H: IsValidNextBlock _ _ |- _] =>
         rewrite (proj1 H), IH, sumZ_seq_S; auto
       end.
-    + erewrite block_header_post_step; eauto.
+    + erewrite block_header_post_action; eauto.
     + intuition.
 Qed.
 End Circulation.

theories/Congress.v

@@ -773,8 +773,8 @@ Proof.
   assert (address_is_contract contract = true) as addr_format by eauto.
   remember empty_state eqn:eq.
   (* Contract cannot have been deployed in empty trace so we solve that immediately. *)
-  induction trace as [|? ? ? evts IH evt]; subst; try solve_by_inversion.
-  destruct_chain_event.
+  induction trace as [|? ? ? steps IH step]; subst; try solve_by_inversion.
+  destruct_chain_step.
   - (* New block added, does not change any of the values *)
     (* so basically just use IH directly. *)
     rewrite queue_prev in *.
@@ -787,7 +787,7 @@ Proof.
     cbn [trace_txs].
     rewrite queue_prev, queue_new in *.
     remember (chain_state_env prev).
-    destruct_chain_step; subst pre; cbn [step_tx].
+    destruct_action_eval; subst pre; cbn [eval_tx].
     + (* Transfer step: cannot be to contract, but can come from contract. *)
       rewrite_environment_equiv.
       specialize_hypotheses.
@@ -820,7 +820,7 @@ Proof.
         simpl_hyp_invariant.
         simpl_goal_invariant.
         (* Outgoing transactions is 0 *)
-        fold (outgoing_txs evts contract).
+        fold (outgoing_txs steps contract).
         rewrite undeployed_contract_no_out_txs; auto.
         cbn. lia.
     + (* Call. *)
@@ -842,15 +842,15 @@ Proof.
         match goal with
         | [H1: wc_receive _ _ _ _ _ = Some _,
            H2: contract_state _ _ = Some _ |- _] =>
-          generalize (wc_receive_state_well_behaved _ _ _ _ _ _ _ _ _ evts H2 H1)
+          generalize (wc_receive_state_well_behaved _ _ _ _ _ _ _ _ _ steps H2 H1)
         end.
         simpl_goal_invariant.
         rewrite num_outgoing_acts_call.
 
         intros.
         cbn -[set_contract_state].
-        fold (incoming_txs evts contract) in *.
-        fold (outgoing_txs evts contract) in *.
+        fold (incoming_txs steps contract) in *.
+        fold (outgoing_txs steps contract) in *.
         rewrite address_eq_refl.
         destruct (address_eqb_spec from contract);
           simpl_hyp_invariant;

theories/LocalBlockchain.v

@@ -223,7 +223,7 @@ Section ExecuteActions.
                           | None => act_transfer to amount
                           | Some msg => act_call to amount msg
                           end) ->
-    ChainStep lc_before act lc_after new_acts.
+    ActionEvaluation lc_before act lc_after new_acts.
   Proof.
     intros sent act_eq.
     unfold send_or_call in sent.
@@ -240,7 +240,7 @@ Section ExecuteActions.
       | [p: OakValue * list ActionBody |- _] => destruct p as [new_state resp_acts]
       end.
       Hint Resolve gtb_le : core.
-      apply (step_call from to amount wc msg prev_state new_state resp_acts);