NullPointerException while compile Flat.scala in example project

[jilen]

[info] Compiling 5 Scala sources to /home/jilen/workspace/flow-comprehensions-example/target/scala-2.11/classes...
[error] /home/jilen/workspace/flow-comprehensions-example/Flat.scala:18: exception during macro expansion: 
[error] java.lang.NullPointerException
[error]     at scala.reflect.internal.Types$$anonfun$47.apply(Types.scala:4576)
[error]     at scala.reflect.internal.Types$$anonfun$47.apply(Types.scala:4576)
[error]     at scala.reflect.internal.tpe.TypeComparers$class.isSubType1(TypeComparers.scala:319)
[error]     at scala.reflect.internal.tpe.TypeComparers$class.isSubType(TypeComparers.scala:278)
[error]     at scala.reflect.internal.SymbolTable.isSubType(SymbolTable.scala:16)
[error]     at scala.reflect.internal.Types$class.isSubArg$1(Types.scala:4117)
[error]     at scala.reflect.internal.Types$$anonfun$isSubArgs$2.apply(Types.scala:4120)
[error]     at scala.reflect.internal.Types$$anonfun$isSubArgs$2.apply(Types.scala:4120)
[error]     at scala.reflect.internal.util.Collections$class.corresponds3(Collections.scala:24)
[error]     at scala.reflect.internal.SymbolTable.corresponds3(SymbolTable.scala:16)
[error]     at scala.reflect.internal.Types$class.isSubArgs(Types.scala:4120)
[error]     at scala.reflect.internal.SymbolTable.isSubArgs(SymbolTable.scala:16)
[error]     at scala.reflect.internal.tpe.TypeComparers$class.firstTry$1(TypeComparers.scala:402)
[error]     at scala.reflect.internal.tpe.TypeComparers$class.isSubType2(TypeComparers.scala:552)
[error]     at scala.reflect.internal.tpe.TypeComparers$class.isSubType1(TypeComparers.scala:320)
[error]     at scala.reflect.internal.tpe.TypeComparers$class.isSubType(TypeComparers.scala:278)
[error]     at scala.reflect.internal.SymbolTable.isSubType(SymbolTable.scala:16)
[error]     at scala.reflect.internal.tpe.TypeComparers$class.isWeakSubType(TypeComparers.scala:575)
[error]     at scala.reflect.internal.SymbolTable.isWeakSubType(SymbolTable.scala:16)
[error]     at scala.reflect.internal.Types$Type.weak_$less$colon$less(Types.scala:825)
[error]     at scala.tools.nsc.typechecker.Infer$Inferencer.scala$tools$nsc$typechecker$Infer$Inferencer$$isCompatible(Infer.scala:305)
[error]     at scala.tools.nsc.typechecker.Infer$Inferencer.isWeaklyCompatible(Infer.scala:319)
[error]     at scala.tools.nsc.typechecker.Infer$Inferencer.isConservativelyCompatible(Infer.scala:328)
[error]     at scala.tools.nsc.typechecker.Infer$Inferencer.protoTypeArgs(Infer.scala:417)
[error]     at scala.tools.nsc.typechecker.Typers$Typer.handlePolymorphicCall$1(Typers.scala:3505)
[error]     at scala.tools.nsc.typechecker.Typers$Typer.doTypedApply(Typers.scala:3534)
[error]     at scala.tools.nsc.typechecker.Typers$Typer.normalTypedApply$1(Typers.scala:4545)
[error]     at scala.tools.nsc.typechecker.Typers$Typer.typedApply$1(Typers.scala:4579)
[error]     at scala.tools.nsc.typechecker.Typers$Typer.typedInAnyMode$1(Typers.scala:5342)
[error]     at scala.tools.nsc.typechecker.Typers$Typer.typed1(Typers.scala:5359)
[error]     at scala.tools.nsc.typechecker.Typers$Typer.runTyper$1(Typers.scala:5395)
[error]     at scala.tools.nsc.typechecker.Typers$Typer.scala$tools$nsc$typechecker$Typers$Typer$$typedInternal(Typers.scala:5422)
[error]     at scala.tools.nsc.typechecker.Typers$Typer.body$2(Typers.scala:5369)
[error]     at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:5373)
[error]     at scala.reflect.macros.contexts.Typers$$anonfun$typecheckInternal$1$1.apply(Typers.scala:27)
[error]     at scala.reflect.macros.contexts.Typers$$anonfun$typecheckInternal$1$1.apply(Typers.scala:27)
[error]     at scala.tools.nsc.typechecker.Typers$Typer.silent(Typers.scala:680)
[error]     at scala.reflect.macros.contexts.Typers$class.typecheckInternal$1(Typers.scala:27)
[error]     at scala.reflect.macros.contexts.Typers$$anonfun$typecheck$2$$anonfun$apply$1.apply(Typers.scala:28)
[error]     at scala.reflect.macros.contexts.Typers$$anonfun$typecheck$2$$anonfun$apply$1.apply(Typers.scala:28)
[error]     at scala.reflect.macros.contexts.Typers$$anonfun$3.apply(Typers.scala:24)
[error]     at scala.reflect.macros.contexts.Typers$$anonfun$3.apply(Typers.scala:24)
[error]     at scala.reflect.macros.contexts.Typers$$anonfun$withContext$1$1.apply(Typers.scala:25)
[error]     at scala.reflect.macros.contexts.Typers$$anonfun$withContext$1$1.apply(Typers.scala:25)
[error]     at scala.reflect.macros.contexts.Typers$$anonfun$1.apply(Typers.scala:23)
[error]     at scala.reflect.macros.contexts.Typers$$anonfun$1.apply(Typers.scala:23)
[error]     at scala.reflect.macros.contexts.Typers$class.withContext$1(Typers.scala:25)
[error]     at scala.reflect.macros.contexts.Typers$$anonfun$typecheck$2.apply(Typers.scala:28)
[error]     at scala.reflect.macros.contexts.Typers$$anonfun$typecheck$2.apply(Typers.scala:28)
[error]     at scala.reflect.internal.Trees$class.wrappingIntoTerm(Trees.scala:1716)
[error]     at scala.reflect.internal.SymbolTable.wrappingIntoTerm(SymbolTable.scala:16)
[error]     at scala.reflect.macros.contexts.Typers$class.withWrapping$1(Typers.scala:26)
[error]     at scala.reflect.macros.contexts.Typers$class.typecheck(Typers.scala:28)
[error]     at scala.reflect.macros.contexts.Context.typecheck(Context.scala:6)
[error]     at scala.reflect.macros.contexts.Context.typecheck(Context.scala:6)
[error]     at org.cvogt.flow.transforms.Normalize$$anonfun$rules$13.applyOrElse(Normalize.scala:123)
[error]     at org.cvogt.flow.transforms.Normalize$$anonfun$rules$13.applyOrElse(Normalize.scala:120)
[error]     at scala.runtime.AbstractPartialFunction.apply(AbstractPartialFunction.scala:36)
[error]     at org.cvogt.flow.FlowMacros.org$cvogt$flow$FlowMacros$$traverse$1(flow.scala:223)
[error]     at org.cvogt.flow.FlowMacros.transform(flow.scala:276)
[error]   def showPerson(id: Int): Task[String] = Task.flat{
[error]                                                    ^
[error] one error found
[error] (compile:compileIncremental) Compilation failed
[error] Total time: 1 s, completed 2016-4-18 13:24:10

[cvogt]

@jilen did you change the source code of the examples?

[jilen]

@cvogt No. By the way do you still working on this project ?

[cvogt]

We are planning on yes. Personally I am spending my free time on https://github.com/cvogt/cbt/ at the moment.

[jilen]

@cvogt Thoughtworks each has a serious issue with call-by-name parameter, and seems not able to fix it. Do you think this project would overcome this issue? That is the main reason I give up each

[cvogt]

There are limits to what the desugaring can do. Higher order-functions and call-by-name parameters can't be solved in a general way, only specific to known ones.