Merge pull request #6537 from dotty-staging/add-lets

Add lets as a helper to create bindings

Author: nicolasstucki

library/src-3.x/scala/tasty/reflect/utils/TreeUtils.scala

@@ -23,4 +23,12 @@ trait TreeUtils {
     expr.unseal
   }
 
+  /** Bind the given `terms` to names and use them in the `body` */
+  def lets(terms: List[Term])(body: List[Term] => Term): Term = {
+    def rec(xs: List[Term], acc: List[Term]): Term = xs match {
+      case Nil => body(acc)
+      case x :: xs => let(x) { (x: Term) => rec(xs, x :: acc) }
+    }
+    rec(terms, Nil)
+  }
 }

tests/run-macros/reflect-pos-fun/assert_1.scala

@@ -0,0 +1,23 @@
+import scala.quoted._
+import scala.tasty._
+
+object scalatest {
+
+  inline def assert(condition: => Boolean): Unit = ${ assertImpl('condition) }
+
+  def assertImpl(cond: Expr[Boolean])(implicit refl: Reflection): Expr[Unit] = {
+    import refl._
+    import util._
+
+    cond.unseal.underlyingArgument match {
+      case t @ Apply(TypeApply(Select(lhs, op), targs), rhs) =>
+        let(lhs) { left =>
+          lets(rhs) { rs =>
+            val app = Select.overloaded(left, op, targs.map(_.tpe), rs)
+            val b = app.seal.cast[Boolean]
+            '{ scala.Predef.assert($b) }.unseal
+          }
+        }.seal.cast[Unit]
+    }
+  }
+}

tests/run-macros/reflect-pos-fun/test_2.scala

@@ -0,0 +1,8 @@
+object Test {
+  import scalatest._
+
+  def main(args: Array[String]): Unit = {
+    val l = List(3, 5)
+    assert(l contains 3)
+  }
+}