[Haskell-cafe] problems with trace
George Colpitts
george.colpitts at gmail.com
Fri May 17 21:37:49 UTC 2024
After I load the following into ghci and call main I expect to see "norm"
in the output 3 times as I have called it 3 times but it only shows once.
Why?
traceBug.hs
---------------
{-# OPTIONS_GHC -Wall #-}
import Debug.Trace (trace)
norm :: [Int] -> [Int]
norm = trace ("norm") id
main :: IO ()
main =
do
print $ norm [2]
print $ norm [2]
print $ norm [3]
---------------------
ghci session
% ghci traceBug.hs
Loaded package environment from
/Users/gcolpitts/.ghc/x86_64-darwin-9.8.2/environments/default
GHCi, version 9.8.2: https://www.haskell.org/ghc/ :? for help
[1 of 2] Compiling Main ( traceBug.hs, interpreted )
Ok, one module loaded.
ghci> main
norm
[2]
[2]
[3]
ghci>
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