[clean-list] variable sharing between expressions, gui app prints 42 at the end, rem/mod inconsistency

[Peter Hercek]

Hi all,

A few questions from a beginner :)

Clean language report says that "when a variable occurs more than once 
in a function body, the semantics prescribe that the actual argument is 
shared". So I expected the fib sequence below to have linear (and not 
exponential) complexity.

(>>>) infix 0 :: a !b -> a |toString b
(>>>) val msg = trace_n msg val

take_ul :: !Int [#.a] -> [#.a] | UList a
take_ul 1 [# h : t ] = [# h ]
take_ul n [# h : t ] = [# h : take_ul (n-1) t ]

fib = [# 1, 1 : [# a+b >>> a+b \\ a <|- fib & b <|- tail_ul fib ] ]
where
  tail_ul [# _ : t ] = t

Start = take_ul 4 fib

But it does not seem that the fib sequence is being shared between right 
hand side and left hand side since the computation of the third element 
is being done 2 times as the trace output indicates. Can somebody help 
me out what I'm missing?


Second problem is that a very simple dialog application is printing 42 
at the end (after I confirm the dialog) and waits for keyboard input 
before exiting. How to get rid of this 42 and keyboard input?

% cat hello.icl
module hello
import StdEnv, StdIO

Start world =
  startIO NDI Void (open_dialog) [ProcessClose closeProcess] world
  where
    open_dialog pSt
      # (okId,pSt) = openId pSt
      = snd (openDialog undef (dialog okId) pSt)
    dialog okId = Dialog "Hello Dialog"
      ( TextControl "Hello World, I am a Clean user!" [] :+:
        ButtonControl "OK" [ ControlId okId,
                             ControlFunction quit ]
      ) [ WindowOk okId ]
    quit (ls,pSt) = (ls,closeProcess pSt)
% ./hello.exe
42
%

I'm trying Windows Clean 2.1.1.

And the last one. Is Sparkle and Std environment supposed to be the 
same? I though it should but Sparkle defines both rem and mod operators 
but Std defines only rem. Also what is the difference between mod and rem?

Peter.