ppetr

http://stackoverflow.com/q/10236953/1333025

I quite enjoyed this exercise. I tried to do it without looking at the answers,
and it was worth it. It took me considerable time, but the result is
surprisingly close to two of the other answers, as well as to
[monad-coroutine](http://hackage.haskell.org/package/monad-coroutine) library.
So I guess this is somewhat natural solution to this problem. Without this
exercise, I wouldn't understand how _monad-coroutine_ really works.

To add some additional value, I'll explain the steps that eventually led me to

ppetr

module CoerceUsingUnsafe where

import Data.IORef
import System.IO.Unsafe (unsafePerformIO)

import Data.Word

{- The trick behind this function is in the `test` experession.
   When we create a new mutable variable in the IO monad,
   it has a side effect of creating it somewhere in the memory.

ppetr

Result size = 325

Main.$fFunctorTreeT_$cfmap
  :: forall a_ajJ b_ajK.
     (a_ajJ -> b_ajK) -> Main.TreeT a_ajJ -> Main.TreeT b_ajK
[GblId,
 Arity=2,
 Caf=NoCafRefs,
 Str=DmdType LS,
 Unf=Unf{Src=<vanilla>, TopLvl=True, Arity=2, Value=True,

ppetr

#!/usr/bin/env python
import hashlib
import sys
input = ['#!/usr/bin/env python', 'import hashlib', 'import sys', 'try: input', 'except NameError: input = []', 'try: trans', "except NameError: trans = lambda x: 'MD5 sum of my source is: ' \\", '                            + hashlib.md5(x).hexdigest()', 'lines = input', 'lines.insert(3, "input = " + repr(input))', "out = '\\n'.join(lines) + '\\n'", 'print trans(out),']
try: input
except NameError: input = []
try: trans
except NameError: trans = lambda x: 'MD5 sum of my source is: ' \
                            + hashlib.md5(x).hexdigest()
lines = input

ppetr

{
module Parser where

import Data.Char


-- | Built-in functions in our language:
data BuiltFn
    = Nat Integer   -- ^ Natural number
  deriving (Eq, Ord, Read, Show)

ppetr

import Control.Monad
import Data.Conduit.Internal
import Data.Void

import Data.Sequence

type PipeF i o u m r = Pipe Void i (Either i o) u m r 

-- | Implements feedback for a `PipeF`, converting it to `Pipe`.
-- Any leftover feedback not consumed by the pipe (or produced after its

ppetr

/*
  BSD3 license
  ------------

  Copyright (c) 2013, Petr Pudlák
  All rights reserved.

  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions are met:

ppetr

import java.nio._
import java.nio.channels.Channels
import java.io.{ FileInputStream, IOException }
import java.util.zip._
import scala.util.control.Exception._
import conduit._
import conduit.Pipe._

object CloseExample extends App {
    /**

ppetr

public final class None<T>
    extends AbstractCollection<T>
    implements Option<T>
{

    public None() {}

    public T get() {
        throw new IllegalArgumentException("No value");
    }

ppetr

{-# LANGUAGE RankNTypes #-}
import Control.Monad
import Control.Monad.State
import Control.Monad.Writer
import Data.Char (intToDigit)
import Data.Machine
import Data.Machine.Plan
import Data.Machine.Source
import Data.Monoid