Frederik Eaton wrote:
Hello,
I have a proposal for ghc. I think that it should take a new option, say "--make-command". This will specify a command to be run whenever a source file is read in by ghc. The command will be passed an argument, which is the name of the source file. The idea is that the command can be used to create auto-generated "source" files when ghc needs them.
The purpose of this would be the following. Suppose I have a source file, say Source.hs, which is generated from some template, say Source.hs.in. If I edit Source.hs.in, and compile my program with 'ghc --make', then the copy of Source.hs which ghc uses will be out of date. That's because ghc doesn't know about the fact that Source.hs is generated from Source.hs.in. If I use ghc, then I'll have to remember to manually generate a new version of Source.hs every time I modify Source.hs.in.
But under the present proposal, I would simply write a Makefile with the rules for generating Source.hs, and then pass --make-command=make to ghc. For instance, my Makefile might say:
Source.hs: Source.hs.in $(TAC) < $< > $@
Then every time I run ghc, and Source.hs is out of date, an up-to-date version of Source.hs will be generated automatically - because ghc will call 'make Source.hs' before reading it in.
Does this sound like a good idea?
Since you already have a Makefile, why not add this to it: SRCS = Source.hs ... prog: $(SRCS) ghc --make $(SRCS) -o prog and then just say 'make' to build your program? Surely that's easier than typing 'ghc --make-command=make ...'? Maybe I'm missing something? Cheers, Simon