some basic macros with quasiquotes. Accompanies this blog post <http://imranrashid.com/posts/learning-scala-macros/>. Partially a translation of this example <http://www.warski.org/blog/2012/12/starting-with-scala-macros-a-short-tutorial/> to quasiquotes.

badValDefMacro.scala

def getValMacro(c: Context)(s: c.Expr[Any]) : c.Expr[Any] = {
  import c.universe._
  val q"val $name = $value" = s.tree
  c.Expr(value)
}

def getVal(s: Any) = macro getValMacro

getVal{val x = 17}
error: exception during macro expansion: 
scala.MatchError: {
  val x: Int = 17;
  ()
} (of class scala.reflect.internal.Trees$Block)
	at .getValMacro(<console>:13)

correctDebugMacro.scala

import language.experimental.macros
import reflect.macros.Context
import scala.annotation.StaticAnnotation
import scala.reflect.runtime.{universe => ru}


def debugMacro(c: Context)(s: c.Expr[Any]) : c.Expr[Any] = {
  import c.universe._
  val paramRep = show(s.tree)
  c.Expr(q"""println($paramRep + " = " + $s)""")
}


def debug(s: Any) = macro debugMacro

correctValDefMacro.scala

def getValMacro(c: Context)(s: c.Expr[Any]) : c.Expr[Any] = {
  import c.universe._
  val q"val $name = $value" = s.tree match {case Block(List(valdef),_) => valdef}
  c.Expr(value)
}
def getVal(s: Any) = macro getValMacro

scala> getVal{val x = 17}
res5: Int = 17

macroValDefInput.scala

def printTreeMacro(c: Context)(s: c.Expr[Any]) : c.Expr[Any] = {
  println(showRaw(s.tree))
  c.universe.reify{()}
}
def printTree(s:Any) = macro printTreeMacro

scala> printTree{val x = 17}
Block(List(ValDef(Modifiers(0, , List()), x, TypeTree(), Literal(Constant(17)))), Literal(Constant(())))

quasiValDefTree.scala

scala> showRaw(q"val x = 17")
res0: String = ValDef(Modifiers(), newTermName("x"), TypeTree(), Literal(Constant(17)))

useDebug.scala

scala> val x = 17
x: Int = 17

scala> debug(x)
$line23.$read.$iw.$iw.$iw.x = 17

wrongDebug.scala

scala> def debugMacro(c: Context)(s: c.Expr[Any]) : c.Expr[Any] = {
     |   import c.universe._
     |   val paramRep = show(s.tree)
     |   q"""println($paramRep + " = " + $s)"""
     | }
<console>:19: error: type mismatch;
 found   : c.universe.Apply
 required: c.Expr[Any]
    (which expands to)  c.universe.Expr[Any]
  q"""println($paramRep + " = " + $s)"""
  ^

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