When I run cabal build for my project, it places my compiled executable in
dist-newstyle/build/$PLATFORM/$GHC/$PACKAGE-$VERSION/x/$PACKAGE/build/$PACKAGE/$PACKAGE
I'm using a Makefile to run cabal build as needed when I need to run the executable.
Since I'm working on different platforms at various times, I need a way to tell my Makefile what to expect the $PLATFORM value to be.
There's a couple ways I could go about this:
run cabal build once unconditionally, and then use wildcards:
BIN := $(wildcard dist-newstyle/build/*/ghc-*/foo-*/x/foo/build/foo/foo)
use uname to predict what the platform will be
BIN := dist-newstyle/build/$(shell uname -m)-$(shell uname -s | some magic)/ghc-$(shell ghc --version | some magic)/foo-$(VERSION)/x/foo/build/foo/foo
give up on making sure the binary is up to date within the Makefile and just run cabal run unconditionally
Any of those would work, but I would like to know if I could just ask cabal to tell me where it expects to place an executable.
Is there a cabal command I can run to tell me what $PLATFORM and/or $GHC values it detects?
Since cabal 3.8, you can use the list-bin command:
$ cabal list-bin my-executable-name
That will print the path at which cabal will place the executable if built. Note that it doesn't actually guarantee that the executable is built, so depending on your use case you might want to check that too.