lihaoyi/sourcecode

Ghost

@ghost~540393fe163965c9bc2018ce

dang

you might have to add the type params to someApi

you could try using the partially applied trick that scalaz and cats use, see EitherT's companion

but it's ugly as hell and I actually prefer the explicit type params instead of that hack

Ólafur Páll Geirsson

@olafurpg

@nafg the Text macro doesn't seem to work with lambdas, I get a "identifier expected but integer literal found." error

I'm curious if tweaking the type parameters helps

trait Copyable[T] {
  def copy(e: T, string: String): T
}
object Copyable {
  implicit def functionCopyable[A, B]: Copyable[A => B] = new Copyable[A => B] {
    override def copy(e: A => B, string: String): A => B = new (A => B) {
      override def apply(v1: A): B = e(v1)
      override def toString(): String = string
    }
  }
}

object DebugFun {
  def apply[T](f: sourcecode.Text[T])(implicit ev: Copyable[T]): T =
    ev.copy(f.value, f.source)
}
    val fun = DebugFun { x: Int => // error: Identifier expected but integer literal found.
      x + 2
    }

Ghost

@ghost~540393fe163965c9bc2018ce

that's really annoying, because lambdas are one of the most compelling usecases for seeing the text

btw, I have a PR open in this area...

Ólafur Páll Geirsson

@olafurpg

It's not an inherent limitation, it's an implementation quirk

Ghost

@ghost~540393fe163965c9bc2018ce

lihaoyi/sourcecode#42

btw builds are all failing until scala-native is updated

(I really wish native/scalajs building happened in a parallel universe)

nafg

@nafg

@olafurpg interesting. Does that at least get past the type inference issue? In other words would this work? def m(f: String => Boolean); DebugFun(_ == "hello")

Ólafur Páll Geirsson

@olafurpg

@nafg I didn't get past the "Identifier expected but integer literal found." error

but it seems to infer the correct type

nafg

@nafg

it's really an orthogonal matter to sourcecode

Oron Port

@soronpo

Is there a way I can get the name in the following case:

abstract class Foo {//Can add any implicit I want here
  def getName =  ???
}
val nice = new Foo {}
assert(nice.getName == "nice")

nafg

@nafg

Doesn't Name work?

Oron Port

@soronpo

Nope

  abstract class Foo(implicit n : sourcecode.Name) {
    def getName = n.value
  }
  val nice = new Foo {}
  println(nice.getName)

Prints $anon

Oron Port

@soronpo

The following works as expected:

  abstract class Foo(implicit n : sourcecode.Name) {
    def getName = n.value
  }
  object Foo {
    def apply()(implicit n : sourcecode.Name) = new Foo {}
  }
  val nice = Foo()

Prints nice

For my use-case I must have the new Foo{} form. Java reflection it is :worried:

Oron Port

@soronpo

Hmmm... sourcecode.Enclosing knows nice. Perhaps sourcecode.Name should special case anonymous classes. @lihaoyi your thoughts?

Li Haoyi

@lihaoyi

yeah

it’s probably a bug

iirc i wanted to skip them

skip anonymous enclosing owners to find the first named one

send a pr

Oron Port

@soronpo

created a PR. lihaoyi/sourcecode#48

Oron Port

@soronpo

@lihaoyi What are your thoughts about expanding the library so it would return a singleton string instead of string? With singletons we can create compile-time computations and checks?

Li Haoyi

@lihaoyi

uhh no idea

don’t know anything about singleton types :

maybe send a pr showing what it would look like and what use cases it would allow?

Oron Port

@soronpo

It can be used for linting like this (along with singleton-ops)

class Foo
def foo[N](implicit n : sourcecode.Name.Aux[N], r : Require[SubString[N, 3]=="foo", "variable name must begin with 'foo'"]) : Foo = new Foo

val foo1 = foo() //OK
val goo1 = foo() //Compile-time fail: variable name must begin with 'foo'

Additionally, I can create custom naming compositions to occur at compile-time, instead of run-time.

Nick Childers

@Voltir

er, has anyone seen this error before: could not find implicit value for parameter name: sourcecode.Name

erp, nevermind

was 2.12.5 macro death - upgrading to 2.12.6 fixed it

Oron Port

@soronpo

@lihaoyi, consider the following:

abstract class Foo(implicit n : sourcecode.Name) {
  def getName = n.value
}
val wrapper : Foo = {
  println(new Foo{}.getName)
  new Foo{}
}
println(wrapper.getName)

This will print

wrapper
wrapper

Is it possible to modify the macro so it would print:

$anon
wrapper

Ólafur Páll Geirsson

@olafurpg

@soronpo I think the owner chain is identical for those two

Oron Port

@soronpo

It is, as far as I can tell. Is there no way to know which is the last expression (in the block)?

Matthew Tovbin

@tovbinm

Howdy, I am trying to get a handle on the class name for lambda functions like this Seq(1, 2, 3).map(x => x + 1).map(x => x / 2). In Scala 2.11.x it becomes class anonfun$1 which is super ugly.

I would like to have the generated class name to be a bit nicer. Say MyAppFunL1C20 meaning file MyApp.scala + Line 2 + Column 20.

I believe it's not currently possible to do with sourcecode library, so my question is - is it valuable enough to have in a library? or should I try writing my own macro for it?

Oron Port

@soronpo

I think this is very application specific

You can have an implicit that gets both name and location and in your application you implement the mechanism if (x.name.value.contains("$")) ...

Matthew Tovbin

@tovbinm

I would like to be able to serialize a sequence of lambda transformations and it seems to be possible now with scala 2.11.x just by just serializing the class names anonfun$1, anonfun$23, anonfun$41 etc, and then using reflection to insatiate classes.
the problem that these classes are fragile to code changes and do not uniquely identify the actual function in the user's code.

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