Goal:
  
  A : Type
  B : Type
  f : A → B
  l : list A
  g : ∀ x : A, In x l → B
  Heqg : g = λ (x : A) (_ : In x l), f x
  packcall := {|
                pr1 := A;
                pr2 := {| pr1 := B; pr2 := {| pr1 := l; pr2 := g |} |}
              |}
           : sigma
               (λ A : Type,
                  sigma
                    (λ B : Type, sigma (λ l : list A, ∀ x : A, In x l → B)))
  packcall_fn := {|
                   pr1 := packcall;
                   pr2 :=
                     map_In (pr1 (pr2 (pr2 packcall)))
                       (pr2 (pr2 (pr2 packcall)))
                 |}
              : sigma
                  (λ projs : sigma
                               (λ A : Type,
                                  sigma
                                    (λ B : Type,
                                       sigma
                                         (λ l : list A, ∀ x : A, In x l → B))),
                     list (pr1 (pr2 projs)))
  ============================
   (packcall_fn =
    {|
      pr1 :=
        {|
          pr1 := A; pr2 := {| pr1 := B; pr2 := {| pr1 := l; pr2 := g |} |}
        |};
      pr2 :=
        map_In
          (pr1
             (pr2
                (pr2
                   {|
                     pr1 := A;
                     pr2 := {| pr1 := B; pr2 := {| pr1 := l; pr2 := g |} |}
                   |})))
          (pr2
             (pr2
                (pr2
                   {|
                     pr1 := A;
                     pr2 := {| pr1 := B; pr2 := {| pr1 := l; pr2 := g |} |}
                   |})))
    |} → let H := CoreTactics.block in map_In l g = map f l)


DEBUG:Going to execute:
refine (DepElim.eq_simplification_sigma1_dep _ _ _ _ _)
Level 1: Backtrace:

In environment
A : Type
B : Type
f : A → B
l : list A
g : ∀ x : A, In x l → B
Heqg : g = λ (x : A) (_ : In x l), f x
packcall := {|
              pr1 := A;
              pr2 := {| pr1 := B; pr2 := {| pr1 := l; pr2 := g |} |}
            |}
 : sigma
     (λ A : Type,
        sigma (λ B : Type, sigma (λ l : list A, ∀ x : A, In x l → B)))
packcall_fn := {|
                 pr1 := packcall;
                 pr2 :=
                   map_In (pr1 (pr2 (pr2 packcall)))
                     (pr2 (pr2 (pr2 packcall)))
               |}
 : sigma
     (λ projs : sigma
                  (λ A : Type,
                     sigma
                       (λ B : Type, sigma (λ l : list A, ∀ x : A, In x l → B))),
        list (pr1 (pr2 projs)))
The term "DepElim.eq_simplification_sigma1_nondep_dep ?p ?q ?x ?y ?y0"
has type
 "∀ e : {| pr1 := ?p; pr2 := ?x |} = {| pr1 := ?q; pr2 := ?y |}, ?B e"
while it is expected to have type
 "packcall_fn =
  {|
    pr1 :=
      {| pr1 := A; pr2 := {| pr1 := B; pr2 := {| pr1 := l; pr2 := g |} |} |};
    pr2 :=
      map_In
        (pr1
           (pr2
              (pr2
                 {|
                   pr1 := A;
                   pr2 := {| pr1 := B; pr2 := {| pr1 := l; pr2 := g |} |}
                 |})))
        (pr2
           (pr2
              (pr2
                 {|
                   pr1 := A;
                   pr2 := {| pr1 := B; pr2 := {| pr1 := l; pr2 := g |} |}
                 |})))
  |} → let H := CoreTactics.block in map_In l g = map f l"
(cannot instantiate "?P" because "projs" is not in its scope: available
arguments are "A" "B" "f" "l" "g" "Heqg" "packcall" 
"packcall_fn").
Level 1: Backtrace:

In environment
A : Type
B : Type
f : A → B
l : list A
g : ∀ x : A, In x l → B
Heqg : g = λ (x : A) (_ : In x l), f x
packcall := {|
              pr1 := A;
              pr2 := {| pr1 := B; pr2 := {| pr1 := l; pr2 := g |} |}
            |}
 : sigma
     (λ A : Type,
        sigma (λ B : Type, sigma (λ l : list A, ∀ x : A, In x l → B)))
packcall_fn := {|
                 pr1 := packcall;
                 pr2 :=
                   map_In (pr1 (pr2 (pr2 packcall)))
                     (pr2 (pr2 (pr2 packcall)))
               |}
 : sigma
     (λ projs : sigma
                  (λ A : Type,
                     sigma
                       (λ B : Type, sigma (λ l : list A, ∀ x : A, In x l → B))),
        list (pr1 (pr2 projs)))
The term "DepElim.eq_simplification_sigma1_nondep_dep ?p ?q ?x ?y ?y0"
has type
 "∀ e : {| pr1 := ?p; pr2 := ?x |} = {| pr1 := ?q; pr2 := ?y |}, ?B e"
while it is expected to have type
 "packcall_fn =
  {|
    pr1 :=
      {| pr1 := A; pr2 := {| pr1 := B; pr2 := {| pr1 := l; pr2 := g |} |} |};
    pr2 :=
      map_In
        (pr1
           (pr2
              (pr2
                 {|
                   pr1 := A;
                   pr2 := {| pr1 := B; pr2 := {| pr1 := l; pr2 := g |} |}
                 |})))
        (pr2
           (pr2
              (pr2
                 {|
                   pr1 := A;
                   pr2 := {| pr1 := B; pr2 := {| pr1 := l; pr2 := g |} |}
                 |})))
  |} → let H := CoreTactics.block in map_In l g = map f l"
(cannot instantiate "?P" because "projs" is not in its scope: available
arguments are "A" "B" "f" "l" "g" "Heqg" "packcall" 
"packcall_fn").