scalaz - Printing Input + Function Output with IO -


i wrote simple function (i intended) print out (1) user input + (2) input "foobar" added it:

import scalaz.effect.io import scalaz.effect.io._  def simpleprint: (io[unit], io[string]) = {     val input = readln     val result = input.map(_ + "foobar")     (input.flatmap(putstrln), result) }  def runexample: unit = {     val (in, result) = simpleprint     println(">" + in.unsafeperformio)     println(result.unsafeperformio) }

entering repl, tested out.

when ran runexample method, typed "555", saw output, , typed "1234".

scala> net.repl.foo.runexample 555 >() 1234foobar

i had expected type: "555", , see:

>555 555foobar

how can change above method this?

if you're calling unsafeperformio more once, there's problem program (and ideally you'd use safeapp , not call @ all). mixing untracked effects , io unnecessarily messy. want all of effects sequenced, this:

scala> val action = putstrln(">") >> readln.map(_ + "foobar") >>= putstrln action: scalaz.effect.io[unit] = scalaz.effect.iofunctions$$anon$6@5a2ab2df  scala> action.unsafeperformio > 555foobar

this doesn't echo characters while typing, though. i'm pretty sure i've written code (with getchar , hand-rolled unfoldwhilem), , try dig later if you're interested.


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