Expr wraps an abstract syntax tree and tags it with its type. The main source of information about exprs is the scala.reflect.api.Exprs page.
Constructor/Extractor for Expr.
Can be useful, when having a tree and wanting to splice it in reify call, in which case the tree first needs to be wrapped in an expr.
The main source of information about exprs is the scala.reflect.api.Exprs page.
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Licensed under the Apache License, Version 2.0.
https://www.scala-lang.org/api/2.13.0/scala-reflect/scala/reflect/api/Exprs.html
EXPERIMENTAL
A trait that defines strongly-typed tree wrappers and operations on them for use in Scala Reflection.
Expr
wraps an abstract syntax tree (scala.reflect.api.Trees#Tree) and tags it with its type (scala.reflect.api.Types#Type).Usually
Expr
s are created via scala.reflect.api.Universe#reify, in which case a compiler produces a scala.reflect.api.TreeCreator for the provided expression and also creates a complementary scala.reflect.api.TypeTags#WeakTypeTag that corresponds to the type of that expression.Expr
s can also be created manually via theExpr
companion object, but then the burden of providing aTreeCreator
lies on the programmer. Compile-time reflection via macros, as described in scala.reflect.macros.Aliases, provides an easier way to instantiate exprs manually. Manual creation, however, is very rarely needed when working with runtime reflection.Expr
can be migrated from one mirror to another by using thein
method. Migration means that all symbolic references to classes/objects/packages in the expression are re-resolved within the new mirror (typically using that mirror's classloader). The default universe of anExpr
is typically scala.reflect.runtime#universe, the default mirror is typically scala.reflect.runtime#currentMirror.