with LOG & s3 being abstract vals in the inter...

# arrow

[Bob Glamm]

with LOG & s3 being abstract vals in the interfaces

[raulraja]

yes that is common

[raulraja]

or you can instead use classes and delegation

[Bob Glamm]

mm, can I delegate to more than one instance? I figured that only one instance could be supplied to by

[raulraja]

only one instance can be supplied to by

[raulraja]

but you can have multiple delegations

[raulraja]

https://gist.github.com/raulraja/97e2d5bf60e9d96680cf1fddcc90ee67

[raulraja]

that is a DI example

[raulraja]

it’s one of the multiple techniques

[raulraja]

that uses R type arguments that you constrain by powers and the edge you materialize a module with all the concrete instances

[raulraja]

The module uses delegation to conform the type param R

[raulraja]

Here is another style without type arguments that uses delegation at different layers to activate syntax

[raulraja]

https://gist.github.com/raulraja/e5f09c0cbd1392cf4eee5415150ebf76

[raulraja]

the code may be old but the DI concept is illustrated in the delegation

[Bob Glamm]

thanks

[Bob Glamm]

Ahh in the second file in the gist, I see now

[raulraja]

The approach with abstract properties in interfaces is another approach

[raulraja]

the one you mention is the one Arrow uses for its own type classes

[raulraja]

if you define your algebras as type classes then you can export the syntax everywhere with @extension

[raulraja]

in the same way we do in Arrow

[Bob Glamm]

I'm not certain how much business logic warrants being a typeclass

[raulraja]

https://gist.github.com/raulraja/f94af921749b6c0d67547f1d2398d3df

[raulraja]

That is an example of that but really the technique can be used regardless of your algebra having laws or just being a bunch of IO operations

[Bob Glamm]

thanks, I will take a look. Logger syntax may be useful to export everywhere