Ocaml - wrong type
I want check if tree is balanced (It means that each leaf is on the same depth) but I have problem with wrong type.
type 'a tree = Node of 'a * 'a tree list;;
let rec fold_tree f (Node (x,l)) =
f x (map (fold_tree f) l);;
let is_balanced t =
fst(
fold_tree
(fun _ (l: (bool * int) list ) ->
((fold_left
(fun h (flag,first_value)->
((fst h)=first_value)&&flag,first_value)
(true,snd(hd l) )
l))
)
t);;
The problem is there:
((fold_left(fun h (flag,first_value)-> ((fst h)=first_value)&&flag,first_value) (true,snd(hd l) ) l))
Ocaml tells me that this is type of bool * bool but I am convinced that this is type of bool * int because l is type of (bool * int) list so hd l is type of (bool * int) so snd(hd l) is type of int...
types ocaml
edited Nov 12 at 13:16
Julien
3377
asked Nov 12 at 12:33
mvxxx
556
add a comment |
I want check if tree is balanced (It means that each leaf is on the same depth) but I have problem with wrong type.
type 'a tree = Node of 'a * 'a tree list;;
let rec fold_tree f (Node (x,l)) =
f x (map (fold_tree f) l);;
let is_balanced t =
fst(
fold_tree
(fun _ (l: (bool * int) list ) ->
((fold_left
(fun h (flag,first_value)->
((fst h)=first_value)&&flag,first_value)
(true,snd(hd l) )
l))
)
t);;
The problem is there:
((fold_left(fun h (flag,first_value)-> ((fst h)=first_value)&&flag,first_value) (true,snd(hd l) ) l))
Ocaml tells me that this is type of bool * bool but I am convinced that this is type of bool * int because l is type of (bool * int) list so hd l is type of (bool * int) so snd(hd l) is type of int...
types ocaml
edited Nov 12 at 13:16
Julien
3377
asked Nov 12 at 12:33
mvxxx
556
add a comment |
I want check if tree is balanced (It means that each leaf is on the same depth) but I have problem with wrong type.
type 'a tree = Node of 'a * 'a tree list;;
let rec fold_tree f (Node (x,l)) =
f x (map (fold_tree f) l);;
let is_balanced t =
fst(
fold_tree
(fun _ (l: (bool * int) list ) ->
((fold_left
(fun h (flag,first_value)->
((fst h)=first_value)&&flag,first_value)
(true,snd(hd l) )
l))
)
t);;
The problem is there:
((fold_left(fun h (flag,first_value)-> ((fst h)=first_value)&&flag,first_value) (true,snd(hd l) ) l))
Ocaml tells me that this is type of bool * bool but I am convinced that this is type of bool * int because l is type of (bool * int) list so hd l is type of (bool * int) so snd(hd l) is type of int...
types ocaml
edited Nov 12 at 13:16
Julien
3377
asked Nov 12 at 12:33
mvxxx
556
I want check if tree is balanced (It means that each leaf is on the same depth) but I have problem with wrong type.
type 'a tree = Node of 'a * 'a tree list;;
let rec fold_tree f (Node (x,l)) =
f x (map (fold_tree f) l);;
let is_balanced t =
fst(
fold_tree
(fun _ (l: (bool * int) list ) ->
((fold_left
(fun h (flag,first_value)->
((fst h)=first_value)&&flag,first_value)
(true,snd(hd l) )
l))
)
t);;
The problem is there:
((fold_left(fun h (flag,first_value)-> ((fst h)=first_value)&&flag,first_value) (true,snd(hd l) ) l))
Ocaml tells me that this is type of bool * bool but I am convinced that this is type of bool * int because l is type of (bool * int) list so hd l is type of (bool * int) so snd(hd l) is type of int...
types ocaml
types ocaml
edited Nov 12 at 13:16
Julien
3377
asked Nov 12 at 12:33
mvxxx
556
edited Nov 12 at 13:16
Julien
3377
asked Nov 12 at 12:33
mvxxx
556
edited Nov 12 at 13:16
Julien
3377
edited Nov 12 at 13:16
Julien
3377
edited Nov 12 at 13:16
Julien
3377
3377
asked Nov 12 at 12:33
mvxxx
556
asked Nov 12 at 12:33
mvxxx
556
asked Nov 12 at 12:33
mvxxx
556
556
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
Some pieces of advice:
- Name your intermediary functions
- Avoid opening
List
- Avoid using
List.hd(in order properly handle the empty list case) - Believe the typechecker
- Use type annotations when debugging with the typechecker help
In your case, you should have a look at the type of your inner function
fun (h:'a) (flag,first_value): 'a->
(fst h=first_value) && flag,first_value
answered Nov 12 at 13:59
octachron
4,1481413
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
Some pieces of advice:
- Name your intermediary functions
- Avoid opening
List
- Avoid using
List.hd(in order properly handle the empty list case) - Believe the typechecker
- Use type annotations when debugging with the typechecker help
In your case, you should have a look at the type of your inner function
fun (h:'a) (flag,first_value): 'a->
(fst h=first_value) && flag,first_value
answered Nov 12 at 13:59
octachron
4,1481413
add a comment |
Some pieces of advice:
- Name your intermediary functions
- Avoid opening
List
- Avoid using
List.hd(in order properly handle the empty list case) - Believe the typechecker
- Use type annotations when debugging with the typechecker help
In your case, you should have a look at the type of your inner function
fun (h:'a) (flag,first_value): 'a->
(fst h=first_value) && flag,first_value
answered Nov 12 at 13:59
octachron
4,1481413
add a comment |
Some pieces of advice:
- Name your intermediary functions
- Avoid opening
List
- Avoid using
List.hd(in order properly handle the empty list case) - Believe the typechecker
- Use type annotations when debugging with the typechecker help
In your case, you should have a look at the type of your inner function
fun (h:'a) (flag,first_value): 'a->
(fst h=first_value) && flag,first_value
answered Nov 12 at 13:59
octachron
4,1481413
Some pieces of advice:
- Name your intermediary functions
- Avoid opening
List
- Avoid using
List.hd(in order properly handle the empty list case) - Believe the typechecker
- Use type annotations when debugging with the typechecker help
In your case, you should have a look at the type of your inner function
fun (h:'a) (flag,first_value): 'a->
(fst h=first_value) && flag,first_value
answered Nov 12 at 13:59
octachron
4,1481413
answered Nov 12 at 13:59
octachron
4,1481413
answered Nov 12 at 13:59
octachron
4,1481413
answered Nov 12 at 13:59
octachron
4,1481413
4,1481413
add a comment |
add a comment |
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