CODEWITHSUNDEEP
debuggingrecursionf#breakpoints
Oldrich Svec
Oldrich Svec

Reputation: 4231

recursive function and a breakpoint using F#

Consider the following code:

[<EntryPoint>]
let main (args: string []) = 

  let rec main time =
    let newTime = time + 2 // place a breakpoint at this line
    main newTime

  main 0

I am not able to place a breakpoint at the marked line. I meet such problems quite often when using recursive functions and it really makes me not to use them. Is there any simple solution for that?

EDIT: I create a brand new solution and my build command looks like:

'------ Build started: Project: ConsoleApplication4, Configuration: Debug x86 ------ C:\Program Files (x86)\Microsoft F#\v4.0\fsc.exe -o:obj\x86\Debug\ConsoleApplication4.exe -g --debug:full --noframework --define:DEBUG --define:TRACE --doc:bin\Debug\ConsoleApplication4.XML --optimize- --tailcalls- --platform:x86 -r:"C:\Program Files (x86)\Reference Assemblies\Microsoft\FSharp\2.0\Runtime\v4.0\FSharp.Core.dll" -r:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.0\Profile\Client\mscorlib.dll" -r:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.0\Profile\Client\System.Core.dll" -r:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.0\Profile\Client\System.dll" -r:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.0\Profile\Client\System.Numerics.dll" --target:exe --warn:3 --warnaserror:76 --vserrors --LCID:1033 --utf8output --fullpaths --flaterrors "C:\Users\olsv\AppData\Local\Temp.NETFramework,Version=v4.0,Profile=Client.AssemblyAttributes.fs" Program.fs ConsoleApplication4 -> d:\olsv\documents\visual studio 2010\Projects\ConsoleApplication4\ConsoleApplication4\bin\Debug\ConsoleApplication4.exe ========== Build: 1 succeeded or up-to-date, 0 failed, 0 skipped =========='

Upvotes: 1

Views: 785

Answers (2)

Oldrich Svec
Oldrich Svec

Reputation: 4231

So it looks like, that it is a bug. I have already reported it to the F# team. So lets hope that they will fix it soon!

Upvotes: 0

Tomas Petricek
Tomas Petricek

Reputation: 243051

I tried debugging the code you posted and it seems to be working just fine (I'm using Visual Studio 2010 SP1). When I place the breakpoint and run the code (as a console application) it stops at the breakpoint repeatedly and I can step to the next expression and see the state of local variables.

You could try checking compiler flags - the debugging works the best when you disable optimizations and tail-calls (this may be particularly relevant to recursive functions). When I build the project, the flags include the following:--debug:full --optimize- --tailcalls-.

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Upvotes: 4

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