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author | Jon Pretty <jon.pretty@propensive.com> | 2017-11-09 09:20:20 +0000 |
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committer | Jon Pretty <jon.pretty@propensive.com> | 2017-11-09 09:20:20 +0000 |
commit | c5c9c4f1432391f6af9202dd89872e5aae92ca58 (patch) | |
tree | c26bf5007c6204b9274993035c6e5cc9b9d4f9aa /examples/src/main/scala/default.scala | |
parent | 3f23cb5bca4ea8be889b714008a85141fe5e213c (diff) | |
download | magnolia-c5c9c4f1432391f6af9202dd89872e5aae92ca58.tar.gz magnolia-c5c9c4f1432391f6af9202dd89872e5aae92ca58.tar.bz2 magnolia-c5c9c4f1432391f6af9202dd89872e5aae92ca58.zip |
Added Scaladocs
Diffstat (limited to 'examples/src/main/scala/default.scala')
-rw-r--r-- | examples/src/main/scala/default.scala | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/examples/src/main/scala/default.scala b/examples/src/main/scala/default.scala index 55b0753..ea881df 100644 --- a/examples/src/main/scala/default.scala +++ b/examples/src/main/scala/default.scala @@ -6,19 +6,31 @@ import scala.language.higherKinds import magnolia._ import scala.language.experimental.macros +/** typeclass for providing a default value for a particular type */ trait Default[T] { def default: T } +/** companion object and derivation object for [[Default]] */ object Default { + type Typeclass[T] = Default[T] + + /** constructs a default for each parameter, using the constructor default (if provided), + * otherwise using a typeclass-provided default */ def combine[T](ctx: CaseClass[Default, T]): Default[T] = new Default[T] { def default = ctx.construct { param => param.default.getOrElse(param.typeclass.default) } } + /** chooses which subtype to delegate to */ def dispatch[T](ctx: SealedTrait[Default, T])(): Default[T] = new Default[T] { def default: T = ctx.subtypes.head.typeclass.default } + /** default value for a string; the empty string */ implicit val string: Default[String] = new Default[String] { def default = "" } + + /** default value for ints; 0 */ implicit val int: Default[Int] = new Default[Int] { def default = 0 } + + /** generates default instances of [[Default]] for case classes and sealed traits */ implicit def gen[T]: Default[T] = macro Magnolia.gen[T] } |