Add helper methods to parse config directly into an F[_] #29

zakpatterson · 2019-01-10T15:09:06Z

This uses ApplicativeError[F[_], Throwable], which is available on many cats types such as IO, Either[Throwable, ?], etc.

So now you can just do:

val cfg : AppSettings = loadConfigF[IO, AppSettings].unsafeRunSync()

Inspired from pureconfig with cats-effect

Obviously this is just for the case of loading from reference.conf or application.conf as done in typesafe config.

This uses ApplicativeError[F[_], Throwable], which is available on many cats types such as IO, Either[Throwable, ?], etc.

jonas

Thanks a lot. This looks awesome. I have a few suggestions on how to improve the integration.

jonas · 2019-01-11T10:41:35Z

src/main/scala/io.circe.config/package.scala

+    ConfigFactory.load().as[C].leftWiden[Throwable].raiseOrPure[F]
+
+  def loadConfigF[F[_], C : Decoder](path : String)(implicit ev : ApplicativeError[F, Throwable]) : F[C] =
+    ConfigFactory.load().as[C](path).leftWiden[Throwable].raiseOrPure[F]


The way ConfigFactory.load() is used here means that load error won't be caught. I suggest moving these methods to the syntax module either named asF or loadF. That way they can piggy-bag on the existing config parsers and simply focus on conversions for ApplicativeError.

To clarify, my suggest is to add the following code to io.circe.config.syntax.CirceConfigOps:

import cats.ApplicativeError import cats.implicits._ /** * Read config settings into the specified container type. */ def asF[F[_], C: Decoder](implicit ev : ApplicativeError[F, Throwable]) : F[C] = as[C].leftWiden[Throwable].raiseOrPure[F] /** * Read config settings at given path into the specified container type. */ def asF[F[_], C: Decoder](path : String)(implicit ev : ApplicativeError[F, Throwable]) : F[C] = as[C](path).leftWiden[Throwable].raiseOrPure[F]

Ah you're totally right, I get it now. So if there's a syntax error in application.conf or something, there will be a parse exception that won't get caught by .as.

Ok, I'll think about it a bit and add your changes. Thanks!

Added this in 6d76b92

So I took one more stab at single function usage in 8dd4315. I do like the idea of the user not having to import ConfigFactory. Let me know what you think. I can wrap parseResources too if that helps, or i can just remove loadConfigF.

jonas · 2019-01-11T10:42:45Z

src/test/scala/io.circe.config/CirceConfigSpec.scala

@@ -70,6 +72,18 @@ class CirceConfigSpec extends FlatSpec with Matchers {
    assert(AppConfig.as[Nested]("e") == Right(Nested(true)))
  }

+  type ErrorHandler[A] = Either[Throwable, A] // Typically this would be IO or something similar


I suggest to bring in cats-effect as a test dependency so we can use it in the tests below.

Added cats effect and more tests in 6d76b92

Revise loadConfigF test to use IO

zakpatterson · 2019-01-15T01:09:01Z

let me know if i can do anything to help. I can rebase this into one commit so we can have a fresh look on it, or expand documentation and testing? Let me know your feeling.

jonas

A few comments.

jonas · 2019-01-12T21:19:38Z

src/test/scala/io.circe.config/CirceConfigSpec.scala

-import org.scalatest.{ FlatSpec, Matchers }
+import cats.effect.IO
+import cats.implicits._
+import com.typesafe.config.ConfigMemorySize


This import is not needed due to the wildcard import below.

I see, fixed in a8ad180

jonas · 2019-01-12T21:32:46Z

src/main/scala/io.circe.config/package.scala

@@ -54,6 +58,11 @@ import scala.collection.JavaConverters._
 * }}}
 */
 package object config {
+  def loadConfigF[F[_], C : Decoder](implicit ev : ApplicativeError[F, Throwable]) : F[C] =
+    Either.fromTry(Try(ConfigFactory.load())).flatMap(_.as[C]).leftWiden[Throwable].raiseOrPure[F]


Either.catchNonFatal looks more optimal here since it doesn't have to create a Try.

As a second note, I understand the point of wanting to load the default configuration to avoid importing com.typesafe.config.ConfigFactory. However, I'm not sure whether this method belongs in the parser module, which already calls out to ConfigFactory.parse*. I might move the loading + leftWiden there so this call becomes parser.load().asF[C].

Thanks for your comment. I was able to move the load logic into parser. And now that I'm more familiar with parser, I see what you're doing in there, and I was able to do the load operations more in correspondence with the other methods. Hopefully that makes sense.

zakpatterson

...

Update README example

zakpatterson

Note package.scala is left unchanged by this PR

* Remove pureconfig in favor of circe-config This duplicates some work we expect to see integrated in circe/circe-config#29, and we'll have to revisit this if that gets released.

jonas · 2019-01-18T15:29:36Z

Thanks a lot. I'll play a bit with it and release a new version over the weekend!

zakpatterson · 2019-01-18T15:57:18Z

Very cool. thanks for your review!

zakpatterson added 2 commits January 10, 2019 10:05

Add helper methods to parse config directly into an F[_]

d51798b

This uses ApplicativeError[F[_], Throwable], which is available on many cats types such as IO, Either[Throwable, ?], etc.

Match test style

82e544e

zakpatterson mentioned this pull request Jan 10, 2019

Remove pureconfig in favor of circe-config pauljamescleary/scala-pet-store#123

Merged

jonas reviewed Jan 11, 2019

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zakpatterson force-pushed the feature-add-load-config-helper-methods branch from ce59907 to 5ab1f57 Compare January 12, 2019 20:01

zakpatterson added 2 commits January 12, 2019 15:04

Add syntax for reading a config into an F

6d76b92

Revise loadConfigF function to catch loader errors in F

8dd4315

Revise loadConfigF test to use IO

zakpatterson force-pushed the feature-add-load-config-helper-methods branch from 5ab1f57 to 8dd4315 Compare January 12, 2019 20:04

Fix cross compilation problem with .toEither

f7640be

jonas reviewed Jan 16, 2019

View reviewed changes

Revert loadConfigF from package object and tests

bf75883

zakpatterson force-pushed the feature-add-load-config-helper-methods branch from 5a65aeb to 4a51ef4 Compare January 16, 2019 17:34

zakpatterson commented Jan 16, 2019

View reviewed changes

zakpatterson added 2 commits January 16, 2019 12:39

Move loadF abilities into parser object

5c8daeb

Update README example

Remove import duplication

a8ad180

zakpatterson force-pushed the feature-add-load-config-helper-methods branch from 95cde00 to a8ad180 Compare January 16, 2019 17:40

zakpatterson commented Jan 16, 2019

View reviewed changes

zakpatterson added 2 commits January 16, 2019 13:44

Fix whitespace inconsistency

0313767

Add read from path methods for default file resolution

cab6c14

zakpatterson force-pushed the feature-add-load-config-helper-methods branch from 5c8ea02 to cab6c14 Compare January 16, 2019 19:53

jonas merged commit 6b0347f into circe:master Jan 18, 2019

zakpatterson deleted the feature-add-load-config-helper-methods branch January 18, 2019 20:41

jonas mentioned this pull request Jan 20, 2019

Applicative error API #32

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Add helper methods to parse config directly into an F[_] #29

Add helper methods to parse config directly into an F[_] #29

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Add helper methods to parse config directly into an F[_] #29

Add helper methods to parse config directly into an F[_] #29

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