syntax - Custom "let" expression in Scala -

i'd love have let construct similar 1 in haskell in scala. tried few ways, none seems good. here's code:

object customlet extends app {   val data = (i <- 1 1024; j <- 1 512) yield (i % j) * * (i + 1) - 1    def heavycalc() = { println("heavycalc called"); data.sum }    def dosomethingwithres(res: int) = {     println(s"${res * res}")     1   }    def cond(value: int): boolean = value > 256    // not usable, though it's expression (2x heavycalc calls)   def withoutlet() = if (cond(heavycalc())) dosomethingwithres(heavycalc()) else 0    // not expression   def letwithval(): int = {     val res = heavycalc()     if (cond(res)) dosomethingwithres(res)     else 0   }    // lot of code simulate "let", @ least expression   def letwithmatch(): int = heavycalc() match {     case res => if (cond(res)) dosomethingwithres(res) else 0   }    // not perfect solution   // http://stackoverflow.com/questions/3241101/with-statement-equivalent-for-scala/3241249#3241249   def let[a, b](param: a)(body: => b): b = body(param)    // not bad, i'm not sure if handle more bindings @ once   def letwithapp(): int = let(heavycalc()) {res => if (cond(res)) dosomethingwithres(res) else 0}    list[(string, () => int)](     ("withoutlet", withoutlet),     ("letwithval", letwithval),     ("letwithmatch", letwithmatch),     ("letwithapp", letwithapp)   ).foreach(     item => item match {       case (title, func) => {         println(s"executing $title")         val ret = func()         println(s"$title finished $ret")         println()       }     }   ) } 

this ideal of (with 1 binding, more separated ,; not sure in keyword):

  // desired   def lettest(): int =     let res = heavycalc() in       if (cond(res)) dosomethingwithres(res) else 0 

i'm not sure if it's possible, have no experience of advanced scala stuff macros, can't tell.

edit1: clear, main things i'm expecting are: being expression , relatively simple syntax (like 1 outlined above).

you use forward pipe:

object forwardpipecontainer {   implicit class forwardpipe[a](val value: a) extends anyval {     def |>[b](f: => b): b = f(value)   } } 

to used this:

import forwardpipecontainer._  def f(i: int) = *  println( f(3) |> (x => x * x) ) 

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you can put multiple arguments in tuple:

println( (f(2), f(3)) |> (x => x._1 * x._2) ) 

which looks better if combined partial function synatx:

println( (f(2), f(3)) |> { case (x, y) => x * y } ) 

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this answer variation of what way of reusing function result in scala, , both based on cache intermediate variable in one-liner got initial idea from.