Scala macros is a facility for Scala—a general-purpose programming language—that permits compile-time metaprogramming against Scala syntax trees, from within the Scala language.
Questions tagged [scala-macros]
774 questions
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Can I get the package/owner from a ClassDef in an impl of a Scala macro annotation?
Given (Scala 2.10.3),
package models
@MyAnnotation
case class MyClass()
How do I get the package name in the impl of the macro?
I've tried:
1) A typeCheck like was suggested here, but that results in a stack overflow (although I can see it…
Julian Peeters
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Is there a way to deflate & map bit-mapped database columns into scala objects via slick
This is in continuation to the following post:
How to combine multiple columns in one case class field when using lifted embedding?
I am a great fan of bit fields, wants to use this logic in a project where I am using slick-macros. Unfortunately…
sgireddy
- 155
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Scala macro: rewrite partial function into match
I would like to rewrite partial function into match expression.
//macro and impl
def pfRewrite(pf: PartialFunction[Int, Int]) = macro ResponderImpl.pfRewriteImpl
def pfRewriteImpl(c: Context)(pf: c.Expr[PartialFunction[Int, Int]]) = {
import…
mike
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Access all scoped symbols in Macro
I want to find a scoped symbol by name inside a macro. The symbol might be in a method, var or import. Is there a simple way of doing this? Eg access the Symbol Table?
user3293336
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Scala Macros: How to create setter function for case classes
I would like to use macro to generate a setter for case classes. e.g:
case class Person(name: String, age: Int)
Macro.mkSetter[Person, String]("name") : Person => String => Person
I tried the following implementation but I keep getting the…
Julien Truffaut
- 477
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1 answer
Adding aliases for macro annotations
While doing DSL stuff, I'd like to add several aliases to an existing macro annotation and, if possible, I'd like to avoid typing the macroTransform definition. That is to say that I want to declare an alias for the "macro header", instead of the…
neutropolis
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Scala Macros: get vals from object
I use scala macros for extract all object from package, and then i would like get some values from object:
package example
trait A {}
object B extends A { val test = "test" }
//macro
object Macro
def getVals(packageName: String) = macro…
mike
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Scala Macro Annotations - Why doesn't my class appear to be updated when I use it as a type parameter?
I used Eugene Burmako's macro annotation example from Macro Paradise (thanks Eugene!) and modified here it to add a val to an empty class here.
As an instance, I can call the new val as expected. But when I try to use the updated class as a type…
Julian Peeters
- 853
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How to get Type of arbitrary tree and check its strong/weak conformance?
For example, one need to check whether an expression is of whole number type: Byte, Short, Int, Long but not Double or Float. The following code doesn't always work:
case Apply(Select(q, n), List(rhs)) =>
if (q.tpe.weak_<:<(typeOf[Long])) true…
nau
- 1,145
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Implementing case by case type level functions in Scala
I would like to implement something, probably a macro, to implement something like
Int --> java.lang.Integer
Float --> java.lang.Float
so that I can implement something like
def box[X <: AnyVal : Numeric](x: X) : Boxed[X] = ...
that would cause…
Daniel Mahler
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1 answer
How to run a java program upon compilation of class
I have a java jar I want to invoke when a class is compiled using the Eclipse IDE :
java -jar myjar.jar args1 args2
Is there a java lib I can use for this or perhaps use a Scala macro ?
blue-sky
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`embeddedFile` warns during compilation while using quasiquotes
After I started using quasiquotes for Scala 2.10 via SBT plugin I have warnings as follows:
[warn] embeddedFile--QuasiquoteCompat.scala@e97d744663044acca2f60c8e99547f14:320: Adapting argument list by inserting (): leaky (Object-receiving) target…
Alexander Myltsev
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Is it possible to determine the type of a pattern variable in a Scala macro?
As part of a macro I need to inspect the patterns of case definitions.
Is there a way to determine the type of a pattern variable, or even the whole pattern?
Consider the polymorphic class Data, and a macro which uses a transformer to inspect and…
Martin Zuber
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2 answers
Scala 2.10 Pass field as argument
Think of a case class like this:
case class User(firstname: String, lastname: String)
now think of calling a method check with the firstname
check(User.firstname)
The Problem is, that the method check must have the name of the field too. It must…
user1563700
0
votes
1 answer
DSL for safe navigation operator in Scala
I want to build a Scala DSL to convert from a existing structure of Java POJOs to a structure equivalent to a Map.
However the incoming objects structure is very likely to contain a lot of null references, which will result in no value in the output…
Michel Daviot
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