[Haskell-cafe] trace output statements

Tom Ellis tom-lists-haskell-cafe-2017 at jaguarpaw.co.uk
Sun Dec 23 07:39:42 UTC 2018

On Sat, Dec 22, 2018 at 09:52:18AM +0100, Damien Mattei wrote:
> i have inserted trace statement that output variable
> ... i have strange behavior of output:

Let's take a simpler example.  Do you understand why the trace statments
from this small program appear in the order that they do?  (And for what
it's worth I really think you'll be better off writing programs using do

% cat test.hs
import Debug.Trace

result =
  let a = trace "evaluating a" 2
      b = trace "evaluating b" 10
      c = trace "evaluating c" (a + b)
  in c
~% ghci -e result test.hs
evaluating c
evaluating b
evaluating a

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