shapeless experiments

gistfile1.scala

scala>   import shapeless._
import shapeless._

scala>   import shapeless.ops.function.FnToProduct
import shapeless.ops.function.FnToProduct

scala> 

scala>   // a normal function taking a string and returning 42

scala>   def fn1(a: String) = 42
fn1: (a: String)Int

scala> 

scala>   /**
     |     * A function that takes a function that takes arguments and returns
     |     * a function taking a single HList.
     |     *
     |     * @param fn The function to convert.  Notice that the type is just F; the heavy lifting is done by implicit resolution
     |     * @param fnToProduct The tool you use to convert functions taking arguments to functions taking HLists
     |     * @tparam F The type of the input function
     |     * @tparam L Used by FnToProduct.Aux
     |     * @tparam R Used by FnToProduct.Aux
     |     * @return
     |     */
     |   def convertToFunctionTakingHList[F, L <: HList, R](fn: F)(implicit fnToProduct: FnToProduct.Aux[F, L => R]): fnToProduct.Out = fnToProduct(fn)
convertToFunctionTakingHList: [F, L <: shapeless.HList, R](fn: F)(implicit fnToProduct: shapeless.ops.function.FnToProduct.Aux[F,L => R])fnToProduct.Out

scala> 

scala>   val fn2: FnToProduct.Aux[(String) => Int, (::[String, HNil]) => Int]#Out = convertToFunctionTakingHList(fn1 _)
fn2: shapeless.::[String,shapeless.HNil] => Int = <function1>

scala>   val result = fn2("a string" :: HNil)
result: Int = 42