Dear all, Yesterday I darcs-got the GHC HEAD to play with the debugger and I have the following impressions/bug/suggestions: * I would like to know whether I am debugging mode (i.e. in a breakpoint) or not. For example
*Main> -- normal prompt
and, for example,
*Main:[1] > -- in breakpoint 1
now, if I evaluate expression "e" via "seq e ()" and it happens to trigger breakpoint 2, I would like to see something like
*Main:[1]:[2] >
or some better notation, but you get my point. * The notation for printing a list is non-Haskell, consider the following evaluated head but unevaluated tail:
*Main> :print xs xs = [True | (_t2::[Bool])]
I would have expected "True : (_t2::[Bool])" * Consider the following code:
mymap f [] = [] mymap f (x:xs) = f x:mymap f xs
main = mapM_ putStrLn $ mymap ('a':) ["hello","bye"]
First, I set a breakpoint on line two. When I invoke "main", the breakpoint is triggered two times before "main" is done evaluating. Afterwards, If I type "main" at the ghci prompt again, the breakpoint is not triggered anymore! Even though ":show breaks" lists it. * Again considering the code above, if I break at line 2:
Stopped at FreeVar2.hs:2:17-19 x :: GHC.Base.Unknown f :: t -> a xs :: [GHC.Base.Unknown]
Now I type "f" and the following message appears:
*** Exception: No match in record selector Var.tcTyVarDetails
* I was wondering whether it would be nice to have a "break" function/ primitive, so that you can write:
mymap f [] = [] mymap f (x:xs) = (break (f x):mymap f xs)
with "break" having type "a -> a" and inserting a breakpoint around the argument expression. It is handy to not have to recalculate lines. However I am not so sure anymore. Using line numbers is not as bad as I thought. The debugger is a nice addition to GHC, and I look forward to the debugger being integrated into the Emacs Haskell mode! Cheers, Alexey