[Haskell-cafe] trace

[Daniel Fischer]

Am Donnerstag 24 Dezember 2009 21:31:34 schrieb michael rice:
> Can someone provide a simple example of tracing a function.
>
> Michael

Is

import Debug.Trace

infixl 0 `debug`

debug = flip trace

dfib :: Int -> Integer
dfib =
    let fib 0 = 0
        fib 1 = 1
        fib n = dfib (n-2) + dfib (n-1) `debug` "eval fib " ++ show n
    in (map fib [0 .. ] !!)


*MFib> dfib 12
eval fib 12
eval fib 10
eval fib 8
eval fib 6
eval fib 4
eval fib 2
eval fib 3
eval fib 5
eval fib 7
eval fib 9
eval fib 11
144

the kind of example you're looking for?
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