# Types.Constructor failing on Ruby 3.1
**URL:** https://discourse.dry-rb.org/t/types-constructor-failing-on-ruby-3-1/1566
**Category:** dry-types
**Created:** [December 6, 2022, 5:28pm UTC](https://discourse.dry-rb.org/t/types-constructor-failing-on-ruby-3-1/1566 "2022-12-06T17:28:29Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@eaylward8](https://discourse.dry-rb.org/u/eaylward8)
#### Post date: [December 6, 2022, 5:28pm UTC](https://discourse.dry-rb.org/t/types-constructor-failing-on-ruby-3-1/1566/1 "2022-12-06T17:28:29Z")
I saw Ruby 3.1 issue threads for some other dry gems, but not dry-types. Apologies if I missed this somewhere and am duplicating things.
I was trying to follow along with [this example](https://dry-rb.org/gems/dry-types/1.2/custom-types/#code-types-constructor-code) and hit an error.
Given this class:
```ruby
class User
def initialize(name:)
@name = name
end
end
```
…the docs say I should be able to do this:
```ruby
user_type = Types.Constructor(User)
# It is equivalent to User.new(name: 'John')
user_type[name: 'John']
```
On Ruby 2.7.7, this works as expected and I get an instance of User with the given name.
On Ruby 3.1.2, I get:
```ruby
Dry::Types::CoercionError: wrong number of arguments (given 1, expected 0; required keyword: name)
Caused by ArgumentError: wrong number of arguments (given 1, expected 0; required keyword: name)
from (pry):2:in `initialize'
```
I’m assuming this is due to Ruby 3.1’s changes to how keyword args are handled.
---
### Author:  [@alassek](https://discourse.dry-rb.org/u/alassek)
#### Post date: [December 8, 2022, 5:09am UTC](https://discourse.dry-rb.org/t/types-constructor-failing-on-ruby-3-1/1566/2 "2022-12-08T05:09:38Z")
Confirmed, I see this behavior also. I’m not certain that this actually falls within Dry::Types’s use-case; if you wanted attribute-based types you could use Dry::Struct for that.
I would suggest opening a support ticket on GitHub. In the meantime, you can work around it like this:
```ruby
user_type = Types.Constructor(User) { |input| User.new(**input) }
```
---
### Author:  [@flash-gordon](https://discourse.dry-rb.org/u/flash-gordon)
#### Post date: [December 9, 2022, 8:00am UTC](https://discourse.dry-rb.org/t/types-constructor-failing-on-ruby-3-1/1566/3 "2022-12-09T08:00:23Z")
It’s not a compatible `User` declaration. dry-types doesn’t pass value as keywords. It should be
```auto
class User
def initialize(attributes)
attributes.each { instance_variable_set(:"@{_1}", _2) }
end
end
```
Otherwise, you can use a custom block as @alassek suggested