Re: Proposal: Add getFullProgName

2012/6/20 Johan Tibell :

Hi Heinrich,

On Wed, Jun 20, 2012 at 2:02 AM, Heinrich Apfelmus wrote:

...

The only trouble I have is that these semantics don't seem to be useful.  For what purpose would you like to know the executable path? The only use case that I have encountered is to find data files relative to the program, but in this case, I need it to work equally well in GHCi, runghc and compiled.

The most common use case I can think of is having the binary invoke itself in some way e.g. using execv. The particular use case I have in mind is having the binary copy itself elsewhere (i.e. to another machine) and then execute itself again.

I know this a special case and slightly off-topic. However, I'm not sure, if this use-case provides a good justification for 'getExecutablePath'. Couldn't you just pass an explicit argument with the path to the file to copy when executing this binary? Your shortcut via 'getExecutablePath' somehow reminds me of an arbitrary IO action deep-down in some module trying to call 'main' again. This requires quite some impurity to achieve and entails a slew of composability issues. The pure construction of explicitly passing all arguments was always much simpler in my code. best regards, Simon