Merge branch 'ralf/gen-exercises' into 'master'

Auto-generate exercise files

Closes #4

See merge request tutorial-popl18!4

.gitignore

@@ -26,7 +26,11 @@ _*_.tex
 *.glob
 *.v.d
 *.vio
-Makefile.coq*
+*.vos
+*.vok
+Makefile.coq
+Makefile.coq.conf
+.Makefile.coq.d
 *.crashcoqide
 .coqdeps.d
 build-dep

.gitlab-ci.yml

@@ -5,6 +5,7 @@ stages:
 
 variables:
   CPU_CORES: "10"
+  MAKE_TARGET: "ci"
 
 .template: &template
   stage: build
@@ -40,7 +41,7 @@ build-coq.8.10.1:
 build-iris.dev:
   <<: *template
   variables:
-    OPAM_PINS: "coq version 8.11.dev   coq-stdpp.dev git git+https://gitlab.mpi-sws.org/iris/stdpp.git#$STDPP_REV  coq-iris.dev git git+https://gitlab.mpi-sws.org/iris/iris.git#$IRIS_REV"
+    OPAM_PINS: "coq version 8.12.dev   coq-stdpp.dev git git+https://gitlab.mpi-sws.org/iris/stdpp.git#$STDPP_REV  coq-iris.dev git git+https://gitlab.mpi-sws.org/iris/iris.git#$IRIS_REV"
   except:
   only:
   - triggers

Makefile.coq.local

+# Generate an exercise for each solution.
+SOLUTIONS := $(wildcard solutions/*.v)
+EXERCISES := $(addprefix exercises/,$(notdir $(SOLUTIONS)))
+
+exercises: $(EXERCISES)
+.PHONY: exercises
+
+$(EXERCISES): exercises/%.v: solutions/%.v gen-exercises.awk
+	$(HIDE)echo "Generating exercise file $@ from $<"
+	$(HIDE)gawk -f gen-exercises.awk < $< > $@
+
+# CI make target
+ci: all
+	+@make -B exercises # force make (in case exercise files have been edited directly)
+	if [ -n "$$(git status --porcelain)" ]; then echo 'ERROR: Exercise files are not up-to-date with solutions.'; exit 1; fi

README.md

@@ -58,3 +58,35 @@ If you would like to know more about Iris, we recommend to take a look at:
   Ralf Jung, Robbert Krebbers, Jacques-Henri Jourdan, Aleš Bizjak, Lars
   Birkedal, Derek Dreyer.
   A detailed description of the Iris logic and its model
+
+## Generating the exercises
+
+If you want to contribute to the tutorial, note that the files in `exercises/`
+are generated from the corresponding files in `solutions/`. Run `make exercises`
+to re-generate those files. This requires `gawk` to be installed (which should
+usually be available on Linux but might have to be installed separately on
+macOS).
+
+The syntax for the solution files is as follows:
+```
+(* BEGIN SOLUTION *)
+  solution here.
+(* END SOLUTION *)
+```
+is replaced by
+```
+  (* exercise *)
+Admitted.
+```
+and the more powerful
+```
+(* BEGIN SOLUTION *)
+  solution here.
+(* END SOLUTION BEGIN TEMPLATE
+  exercise template here.
+END TEMPLATE *)
+```
+is replaced by
+```
+  exercise template here.
+```

exercises/ex_01_swap.v

@@ -117,7 +117,7 @@ Lemma rotate_r_spec_again x y z v1 v2 v3 :
     rotate_r #x #y #z
   {{{ RET #(); x ↦ v3 ∗ y ↦ v1 ∗ z ↦ v2 }}}.
 Proof.
-  iIntros (Φ) "(Hx & Hy & Hz) Post". wp_lam.
+  iIntros (Φ) "(Hx & Hy & Hz) Post". wp_lam. do 2 wp_let.
   (* We can shorten the above a bit: Instead of using the [iApply] tactic, we
   can use [wp_apply] which automatically uses [wp_bind] first. Also, it strips
   the later [▷] by calling [iNext] afterwards. *)

exercises/ex_03_spinlock.v

@@ -101,7 +101,8 @@ Section proof.
     destruct b.
     - wp_cmpxchg_fail. iMod ("Hclose" with "[Hl]") as "_".
       { iNext. iExists true. iFrame. }
-      iModIntro. wp_proj. (* exercise *)
+      iModIntro. wp_proj.
+    (* exercise *)
   Admitted.
 
   (** *Exercise*: prove the spec of [acquire]. Since [acquire] is a recursive

exercises/ex_04_parallel_add.v

@@ -36,8 +36,7 @@ Section proof1.
     iIntros (Φ) "_ Post".
     unfold parallel_add. wp_alloc r as "Hr". wp_let.
     wp_apply (newlock_spec (parallel_add_inv_1 r) with "[Hr]").
-    { (* exercise *)
-      admit. }
+    { (* exercise *) admit. }
     iIntros (l) "#Hl". wp_let.
     wp_apply (wp_par (λ _, True%I) (λ _, True%I)).
     - wp_apply (acquire_spec with "Hl"). iDestruct 1 as (n) "[Hr %]".
@@ -105,8 +104,7 @@ Section proof2.
     iMod (ghost_var_alloc 0) as (γ1) "[Hγ1● Hγ1◯]".
     iMod (ghost_var_alloc 0) as (γ2) "[Hγ2● Hγ2◯]".
     wp_apply (newlock_spec (parallel_add_inv_2 r γ1 γ2) with "[Hr Hγ1● Hγ2●]").
-    { (* exercise *)
-      admit. }
+    { (* exercise *) admit. }
     iIntros (l) "#Hl". wp_let.
     wp_apply (wp_par (λ _, own γ1 (◯E 2%Z)) (λ _, own γ2 (◯E 2%Z))
                 with "[Hγ1◯] [Hγ2◯]").
@@ -140,8 +138,7 @@ Section proof3.
     iMod (own_alloc (●F 0 ⋅ ◯F 0)) as (γ) "[Hγ● [Hγ1◯ Hγ2◯]]".
     { by apply auth_both_valid. }
     wp_apply (newlock_spec (parallel_add_inv_3 r γ) with "[Hr Hγ●]").
-    { (* exercise *)
-      admit. }
+    { (* exercise *) admit. }
     iIntros (l) "#Hl". wp_let.
     wp_apply (wp_par (λ _, own γ (◯F{1/2} 2)) (λ _, own γ (◯F{1/2} 2))
                 with "[Hγ1◯] [Hγ2◯]").

exercises/ex_05_parallel_add_mul.v

@@ -62,7 +62,7 @@ Section proof.
     True%I. (* exercise: replace [True] with something meaningful. *)
 
   Lemma parallel_add_mul_spec :
-    {{{ True }}} parallel_add_mul {{{ z, RET #z; ⌜ z = 2 ∨ z = 4 ⌝ }}}.
+    {{{ True }}} parallel_add_mul {{{ z, RET #z; ⌜ z = 2%Z ∨ z = 4%Z ⌝ }}}.
   Proof.
     (* exercise *)
   Admitted.

gen-exercises.awk

+BEGIN {
+    in_solution = 0;
+}
+{ # on every line of the input
+    if (match($0, /^( *)\(\* *BEGIN SOLUTION *\*\)$/, groups)) {
+        in_solution = 1
+    } else if (match($0, /^( *)\(\* *END SOLUTION *\*\)$/, groups)) {
+        print groups[1] "  (* exercise *)"
+        print groups[1] "Admitted."
+        in_solution = 0
+    } else if (match($0, /^( *)\(\* *END SOLUTION BEGIN TEMPLATE *$/, groups)) {
+        in_solution = 0
+    } else if (match($0, /^( *)END TEMPLATE *\*\)$/, groups)) {
+        # Nothing to do, just do not print this line.
+    } else if (in_solution == 0) {
+        gsub("From solutions Require", "From exercises Require")
+        print
+    }
+}

solutions/ex_01_swap.v

@@ -137,9 +137,11 @@ Lemma rotate_l_spec x y z v1 v2 v3 :
     rotate_l #x #y #z
   {{{ RET #(); x ↦ v2 ∗ y ↦ v3 ∗ z ↦ v1 }}}.
 Proof.
+(* BEGIN SOLUTION *)
   iIntros (Φ) "(Hx & Hy & Hz) Post". unfold rotate_l. wp_lam. do 2 wp_let.
   wp_apply (swap_spec with "[$Hx $Hy]"); iIntros "[Hx Hy]"; wp_seq.
   wp_apply (swap_spec with "[$Hy $Hz]"); iIntros "[Hy Hz]".
   iApply ("Post" with "[$]").
 Qed.
+(* END SOLUTION *)
 End proof.

solutions/ex_02_sumlist.v

@@ -117,6 +117,7 @@ Lemma inc_list_spec_induction n l v :
     inc_list #n v
   {{{ RET #(); is_list (map (Z.add n) l) v }}}.
 Proof.
+(* BEGIN SOLUTION *)
   iIntros (Φ) "Hl Post".
   iInduction l as [|x l] "IH" forall (v Φ); simpl.
   - iDestruct "Hl" as %->.
@@ -133,6 +134,7 @@ Proof.
     iExists p. iSplitR; [done|].
     iExists v. iSplitR "Hl"; [iApply "Hp"|iApply "Hl"].
 Qed.
+(* END SOLUTION *)
 
 (** *Exercise*: Now do the proof again using Löb induction. *)
 Lemma inc_list_spec_löb n l v :
@@ -140,6 +142,7 @@ Lemma inc_list_spec_löb n l v :
     inc_list #n v
   {{{ RET #(); is_list (map (Z.add n) l) v }}}.
 Proof.
+(* BEGIN SOLUTION *)
   iIntros (Φ) "Hl Post".
   iLöb as "IH" forall (l v Φ). destruct l as [|x l]; simpl; wp_rec; wp_let.
   - iDestruct "Hl" as %->. wp_match. by iApply "Post".
@@ -148,6 +151,7 @@ Proof.
     wp_apply ("IH" with "Hl"). iIntros "Hl".
     iApply "Post". eauto with iFrame.
 Qed.
+(* END SOLUTION *)
 
 (** *Exercise*: Do the proof of [sum_inc_list] by making use of the lemmas of
 [sum_list] and [inc_list] we just proved. Make use of [wp_apply]. *)
@@ -156,10 +160,12 @@ Lemma sum_inc_list_spec n l v :
     sum_inc_list #n v
   {{{ RET #(sum_list_coq (map (Z.add n) l)); is_list (map (Z.add n) l) v }}}.
 Proof.
+(* BEGIN SOLUTION *)
   iIntros (Φ) "Hl Post". wp_lam. wp_let.
   wp_apply (inc_list_spec_induction with "Hl"); iIntros "Hl /="; wp_seq.
   wp_apply (sum_list_spec_induction with "Hl"); auto.
 Qed.
+(* END SOLUTION *)
 
 (** *Optional exercise*: Prove the following spec of [map_list] which makes use
 of a nested Texan triple, This spec is rather weak, as it requires [f] to be
@@ -168,6 +174,7 @@ Lemma map_list_spec_induction (f : val) (f_coq : Z → Z) l v :
   (∀ n, {{{ True }}} f #n {{{ RET #(f_coq n); True }}}) -∗
   {{{ is_list l v }}} map_list f v {{{ RET #(); is_list (map f_coq l) v }}}.
 Proof.
+(* BEGIN SOLUTION *)
   iIntros "#Hf" (Φ) "!# Hl Post".
   iLöb as "IH" forall (l v Φ). destruct l as [|x l]; simpl; wp_rec; wp_let.
   - iDestruct "Hl" as %->. wp_match. by iApply "Post".
@@ -178,4 +185,5 @@ Proof.
     wp_apply ("IH" with "Hl"). iIntros "Hl".
     iApply "Post". eauto with iFrame.
 Qed.
+(* END SOLUTION *)
 End proof.

solutions/ex_03_spinlock.v

@@ -101,12 +101,15 @@ Section proof.
     destruct b.
     - wp_cmpxchg_fail. iMod ("Hclose" with "[Hl]") as "_".
       { iNext. iExists true. iFrame. }
-      iModIntro. wp_proj. iApply ("HΦ" $! false). done.
+      iModIntro. wp_proj.
+  (* BEGIN SOLUTION *)
+      iApply ("HΦ" $! false). done.
     - (* Exercise *) wp_cmpxchg_suc.
       iMod ("Hclose" with "[Hl]") as "_".
       { iNext. iExists true. iFrame. }
       iModIntro. wp_proj. by iApply ("HΦ" $! true with "HR").
   Qed.
+  (* END SOLUTION *)
 
   (** *Exercise*: prove the spec of [acquire]. Since [acquire] is a recursive
   function, you should use the tactic [iLöb] for Löb induction. Use the tactic
@@ -114,11 +117,13 @@ Section proof.
   Lemma acquire_spec lk R :
     {{{ is_lock lk R }}} acquire lk {{{ RET #(); R }}}.
   Proof.
+  (* BEGIN SOLUTION *)
     iIntros (Φ) "#Hl HΦ". iLöb as "IH". wp_rec.
     wp_apply (try_acquire_spec with "Hl"). iIntros ([]).
     - iIntros "HR". wp_if. by iApply "HΦ".
     - iIntros "_". wp_if. iApply ("IH" with "HΦ").
   Qed.
+  (* END SOLUTION *)
 
   (** *Exercise*: prove the spec of [release]. At a certain point in this proof,
   you need to open the invariant. For this you can use:
@@ -130,9 +135,11 @@ Section proof.
   Lemma release_spec lk R :
     {{{ is_lock lk R ∗ R }}} release lk {{{ RET #(); True }}}.
   Proof.
+  (* BEGIN SOLUTION *)
     iIntros (Φ) "(Hlock & HR) HΦ".
     iDestruct "Hlock" as (l ->) "#Hinv /=".
     wp_lam. iInv lockN as (b) "[Hl _]" "Hclose".
     wp_store. iApply "HΦ". iApply "Hclose". iNext. iExists false. iFrame.
   Qed.
+  (* END SOLUTION *)
 End proof.

solutions/ex_04_parallel_add.v

@@ -36,23 +36,33 @@ Section proof1.
     iIntros (Φ) "_ Post".
     unfold parallel_add. wp_alloc r as "Hr". wp_let.
     wp_apply (newlock_spec (parallel_add_inv_1 r) with "[Hr]").
-    { (* exercise *) iExists 0. iFrame. }
+  (* BEGIN SOLUTION *)
+    { iExists 0. iFrame. }
+  (* END SOLUTION BEGIN TEMPLATE
+    { (* exercise *) admit. }
+  END TEMPLATE *)
     iIntros (l) "#Hl". wp_let.
     wp_apply (wp_par (λ _, True%I) (λ _, True%I)).
     - wp_apply (acquire_spec with "Hl"). iDestruct 1 as (n) "[Hr %]".
       wp_seq. wp_load. wp_op. wp_store.
       wp_apply (release_spec with "[Hr $Hl]"); [|done].
       iExists _. iFrame "Hr". iPureIntro. by apply Zeven_plus_Zeven.
-    - (* exercise *)
-      wp_apply (acquire_spec with "Hl"). iDestruct 1 as (n) "[Hr %]".
+  (* BEGIN SOLUTION *)
+    - wp_apply (acquire_spec with "Hl"). iDestruct 1 as (n) "[Hr %]".
       wp_seq. wp_load. wp_op. wp_store.
       wp_apply (release_spec with "[Hr $Hl]"); [|done].
       iExists _. iFrame "Hr". iPureIntro. by apply Zeven_plus_Zeven.
-    - (* exercise *)
-      iIntros (v1 v2) "_ !>". wp_seq.
+    - iIntros (v1 v2) "_ !>". wp_seq.
       wp_apply (acquire_spec with "Hl"). iDestruct 1 as (n) "[Hr %]".
       wp_seq. wp_load. by iApply "Post".
   Qed.
+  (* END SOLUTION BEGIN TEMPLATE
+    - (* exercise *)
+      admit.
+    - (* exercise *)
+      admit.
+  Admitted.
+  END TEMPLATE *)
 End proof1.
 
 (** 2nd proof : we prove that the program returns 4 exactly.
@@ -62,7 +72,7 @@ Whereas we previously abstracted over an arbitrary "ghost state" [Σ] in the
 proofs, we now need to make sure that we can use integer ghost variables. For
 this, we add the type class constraint:
 
-  inG Σ (authR (optionUR (exclR ZO)))
+  inG Σ (excl_authR ZO)
 
 *)
 
@@ -109,7 +119,11 @@ Section proof2.
     iMod (ghost_var_alloc 0) as (γ1) "[Hγ1● Hγ1◯]".
     iMod (ghost_var_alloc 0) as (γ2) "[Hγ2● Hγ2◯]".
     wp_apply (newlock_spec (parallel_add_inv_2 r γ1 γ2) with "[Hr Hγ1● Hγ2●]").
-    { (* exercise *) iExists 0, 0. iFrame. }
+  (* BEGIN SOLUTION *)
+    { iExists 0, 0. iFrame. }
+  (* END SOLUTION BEGIN TEMPLATE
+    { (* exercise *) admit. }
+  END TEMPLATE *)
     iIntros (l) "#Hl". wp_let.
     wp_apply (wp_par (λ _, own γ1 (◯E 2%Z)) (λ _, own γ2 (◯E 2%Z))
                 with "[Hγ1◯] [Hγ2◯]").
@@ -119,21 +133,27 @@ Section proof2.
       iMod (ghost_var_update γ1 2 with "Hγ1● Hγ1◯") as "[Hγ1● Hγ1◯]".
       wp_apply (release_spec with "[- $Hl Hγ1◯]"); [|by auto].
       iExists _, _. iFrame "Hγ1● Hγ2●". rewrite (_ : 2 + n2 = 0 + n2 + 2)%Z; [done|ring].
-    - (* exercise *)
-      wp_apply (acquire_spec with "Hl"). iDestruct 1 as (n1 n2) "(Hr & Hγ1● & Hγ2●)".
+  (* BEGIN SOLUTION *)
+    - wp_apply (acquire_spec with "Hl"). iDestruct 1 as (n1 n2) "(Hr & Hγ1● & Hγ2●)".
       wp_seq. wp_load. wp_op. wp_store.
       iDestruct (ghost_var_agree with "Hγ2● Hγ2◯") as %->.
       iMod (ghost_var_update γ2 2 with "Hγ2● Hγ2◯") as "[Hγ2● Hγ2◯]".
       wp_apply (release_spec with "[- $Hl Hγ2◯]"); [|by auto].
       iExists _, _. iFrame "Hγ1● Hγ2●". by rewrite -Z.add_assoc.
-    - (* exercise *)
-      iIntros (??) "[Hγ1◯ Hγ2◯] !>". wp_seq.
+    - iIntros (??) "[Hγ1◯ Hγ2◯] !>". wp_seq.
       wp_apply (acquire_spec with "Hl"). iDestruct 1 as (n1 n2) "(Hr & Hγ1● & Hγ2●)".
       wp_seq. wp_load.
       iDestruct (ghost_var_agree with "Hγ1● Hγ1◯") as %->.
       iDestruct (ghost_var_agree with "Hγ2● Hγ2◯") as %->.
       by iApply "Post".
   Qed.
+  (* END SOLUTION BEGIN TEMPLATE
+    - (* exercise *)
+      admit.
+    - (* exercise *)
+      admit.
+  Admitted.
+  END TEMPLATE *)
 End proof2.
 
 (** 3rd proof : we prove that the program returns 4 exactly, but using a
@@ -153,7 +173,11 @@ Section proof3.
     iMod (own_alloc (●F 0 ⋅ ◯F 0)) as (γ) "[Hγ● [Hγ1◯ Hγ2◯]]".
     { by apply auth_both_valid. }
     wp_apply (newlock_spec (parallel_add_inv_3 r γ) with "[Hr Hγ●]").
-    { (* exercise *) iExists 0. iFrame. }
+  (* BEGIN SOLUTION *)
+    { iExists 0. iFrame. }
+  (* END SOLUTION BEGIN TEMPLATE
+    { (* exercise *) admit. }
+  END TEMPLATE *)
     iIntros (l) "#Hl". wp_let.
     wp_apply (wp_par (λ _, own γ (◯F{1/2} 2)) (λ _, own γ (◯F{1/2} 2))
                 with "[Hγ1◯] [Hγ2◯]").
@@ -164,19 +188,25 @@ Section proof3.
         by apply frac_auth_update, (op_local_update_discrete n 0 2). }
       wp_apply (release_spec with "[$Hl Hr Hγ●]"); [|by auto].
       iExists _. iFrame. by rewrite Nat2Z.inj_add.
-    - (* exercise *)
-      wp_apply (acquire_spec with "Hl"). iDestruct 1 as (n) "[Hr Hγ●]".
+  (* BEGIN SOLUTION *)
+    - wp_apply (acquire_spec with "Hl"). iDestruct 1 as (n) "[Hr Hγ●]".
       wp_seq. wp_load. wp_op. wp_store.
       iMod (own_update_2 _ _ _ (●F (n+2) ⋅ ◯F{1/2}2) with "Hγ● Hγ2◯") as "[Hγ● Hγ2◯]".
       { rewrite (comm plus).
         by apply frac_auth_update, (op_local_update_discrete n 0 2). }
       wp_apply (release_spec with "[- $Hl Hγ2◯]"); [|by auto].
       iExists _. iFrame. by rewrite Nat2Z.inj_add.
-    - (* exercise *)
-      iIntros (??) "[Hγ1◯ Hγ2◯] !>". wp_seq.
+    - iIntros (??) "[Hγ1◯ Hγ2◯] !>". wp_seq.
       wp_apply (acquire_spec with "Hl"). iDestruct 1 as (n) "(Hr & Hγ●)".
       wp_seq. wp_load. iCombine "Hγ1◯ Hγ2◯" as "Hγ◯".
       iDestruct (own_valid_2 with "Hγ● Hγ◯") as %->%frac_auth_agreeL.
       by iApply "Post".
   Qed.
+  (* END SOLUTION BEGIN TEMPLATE
+    - (* exercise *)
+      admit.
+    - (* exercise *)
+      admit.
+  Admitted.
+  END TEMPLATE *)
 End proof3.

solutions/ex_05_parallel_add_mul.v

@@ -59,6 +59,7 @@ Section proof.
   and the rules for those as given above. You are allowed to use any number of
   Boolean ghost variables. *)
   Definition parallel_add_mul_inv (r : loc) (γ1 γ2 : gname) : iProp Σ :=
+  (* BEGIN SOLUTION *)
     (∃ (b1 b2 : bool) (z : Z),
         own γ1 (●E b1) ∗ own γ2 (●E b2) ∗ r ↦ #z ∗
        ⌜match b1, b2 with
@@ -66,10 +67,14 @@ Section proof.
         | true,  false => z = 2
         | false, _     => z = 0
         end⌝)%I.
+  (* END SOLUTION BEGIN TEMPLATE
+    True%I. (* exercise: replace [True] with something meaningful. *)
+  END TEMPLATE *)
 
   Lemma parallel_add_mul_spec :
     {{{ True }}} parallel_add_mul {{{ z, RET #z; ⌜ z = 2%Z ∨ z = 4%Z ⌝ }}}.
   Proof.
+  (* BEGIN SOLUTION *)
     iIntros (Φ) "_ Post".
     unfold parallel_add_mul. wp_alloc r as "Hr". wp_let.
     iMod (ghost_var_alloc false) as (γ1) "[Hγ1● Hγ1◯]".
@@ -102,4 +107,5 @@ Section proof.
       iDestruct (ghost_var_agree with "Hγ2● Hγ2◯") as %->.
       auto.
   Qed.
+  (* END SOLUTION *)
 End proof.