Zap in cats?

[Chen Harry]

I am trying to use Cofree to interpret the program written in Free monad. There is a Zap typeclass in Scalaz can help to do that. does Cats have similar typeclass which is equivalent to Scalaz.Zap? or it is a obsolete tech to interpret Free program? 

Thanks,

Harry

[Tony Morris]

It is not obsolete tech to interpret Free program.

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[Chen Harry]

Good to know that. thanks Tony.

[Chen Harry]

I am trying scalaz to interpret Free program by Cofree interpreter: https://gist.github.com/chenharryhua/a4d14896b2a26b30fe85e8d2cac143b1

the program is pretty simple: a traditional terminal DSL. 

my problem is that it is compiled but when I run it, a runtime error occurs: java.lang.ClassCastException: scala.runtime.BoxedUnit cannot be cast to scalaz.Free.

I am highly appreciated if someone give me some clue.

 

Thanks,

Harry

[Chen Harry]

use non-GADT encoding for algebra. it works fine. I've updated the gist. thanks everyone. Ken's code (https://github.com/kenbot/free/blob/master/src/main/scala/kenbot/free/KVS.scala) helps a lot.

[Ken Scambler]

David Laing did some articles & talks on using Cofree a few years ago, which you might find interesting:

http://dlaing.org/cofun/posts/free_and_cofree.html

https://www.youtube.com/watch?v=IhzvLsvRO98

On 15 March 2018 at 10:36, Chen Harry <chen.ha...@gmail.com> wrote:

use non-GADT encoding for algebra. it works fine. I've updated the gist. thanks everyone. Ken's code (https://github.com/kenbot/free/blob/master/src/main/scala/kenbot/free/KVS.scala) helps a lot.

On Wed, Mar 14, 2018 at 9:42 PM Chen Harry <chen.ha...@gmail.com> wrote:

I am trying scalaz to interpret Free program by Cofree interpreter: https://gist.github.com/chenharryhua/a4d14896b2a26b30fe85e8d2cac143b1

the program is pretty simple: a traditional terminal DSL. 

my problem is that it is compiled but when I run it, a runtime error occurs: java.lang.ClassCastException: scala.runtime.BoxedUnit cannot be cast to scalaz.Free.

I am highly appreciated if someone give me some clue.

 

Thanks,

Harry

On Wed, Mar 14, 2018 at 10:30 AM Chen Harry <chen.ha...@gmail.com> wrote:

Good to know that. thanks Tony.

On Tue, Mar 13, 2018 at 9:58 PM Tony Morris <tonym...@gmail.com> wrote:

It is not obsolete tech to interpret Free program.

On 13/03/18 19:21, Chen Harry wrote:

I am trying to use Cofree to interpret the program written in Free monad. There is a Zap typeclass in Scalaz can help to do that. does Cats have similar typeclass which is equivalent to Scalaz.Zap? or it is a obsolete tech to interpret Free program? 

Thanks,

Harry

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[Chen Harry]

Yep.. I referred a few blogs. the one you mentioned is one of them. there are a few also very helpful:

http://abailly.github.io/posts/free.html

http://comonad.com/reader/

On Thu, Mar 15, 2018 at 1:34 PM Ken Scambler <ken.sc...@gmail.com> wrote:

David Laing did some articles & talks on using Cofree a few years ago, which you might find interesting:

http://dlaing.org/cofun/posts/free_and_cofree.html

https://www.youtube.com/watch?v=IhzvLsvRO98

On 15 March 2018 at 10:36, Chen Harry <chen.ha...@gmail.com> wrote:

use non-GADT encoding for algebra. it works fine. I've updated the gist. thanks everyone. Ken's code (https://github.com/kenbot/free/blob/master/src/main/scala/kenbot/free/KVS.scala) helps a lot.

On Wed, Mar 14, 2018 at 9:42 PM Chen Harry <chen.ha...@gmail.com> wrote:

I am trying scalaz to interpret Free program by Cofree interpreter: https://gist.github.com/chenharryhua/a4d14896b2a26b30fe85e8d2cac143b1

the program is pretty simple: a traditional terminal DSL. 

my problem is that it is compiled but when I run it, a runtime error occurs: java.lang.ClassCastException: scala.runtime.BoxedUnit cannot be cast to scalaz.Free.

I am highly appreciated if someone give me some clue.

 

Thanks,

Harry

On Wed, Mar 14, 2018 at 10:30 AM Chen Harry <chen.ha...@gmail.com> wrote:

Good to know that. thanks Tony.

On Tue, Mar 13, 2018 at 9:58 PM Tony Morris <tonym...@gmail.com> wrote:

It is not obsolete tech to interpret Free program.

On 13/03/18 19:21, Chen Harry wrote:

I am trying to use Cofree to interpret the program written in Free monad. There is a Zap typeclass in Scalaz can help to do that. does Cats have similar typeclass which is equivalent to Scalaz.Zap? or it is a obsolete tech to interpret Free program? 

Thanks,

Harry

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