hsvm is a tool that allows you to have multiple GHC versions installed and easily switch between them.
there is no easy-install yet, so you'll need to clone this repo wherever you wish and add the bin/ directory to your $PATH. then, in your .{bash,zsh}rc, add
eval "$(hsvm init)"
and you're ready to hsvm!
eval (hsvm init --fish)
instead.
hsvm commands lists all commands.
hsvm install installs a GHC version into ~/.hsvm. usually these are downloaded from hackage's repository of pre-built GHCs, but you can hsvm install HEAD (which is just an alias to hsvm build-head) to install the latest GHC from git. it will be tagged with the generated GHC version which is (currently) of the form 7.7.YYYYmmdd.
hsvm install takes extra arguments: -3 or --32-bit to force a 32-bit build, -6 or --64-bit to force a 64-bit build, and -v or --verbose to print build output to stdout rather than logging it. when building HEAD, the arch-related flags are ignored.
hsvm build-head is the same as hsvm install HEAD.
hsvm current prints out the currently used GHC.
hsvm use switches the currently used GHC to the specified version.
hsvm versions prints out all the GHCs you have installed.
hsvm rm removes a GHC version.
hsvm rehash refreshes all your symlinks. you should rarely/never need to do this yourself. this command takes its name from rbenv rehash, but since Haskell is a compiled language, rehash has an entirely different purpose.
hsvm init prints out a few lines of shell script which, when executed, set up your hsvm environment. you should put eval "$(hsvm init)" in your .bashrc or .zshrc. fish users should use eval (hsvm init --fish).
hsvm completions lists all possible completions for a command. you should also rarely need to use this yourself.
hsvm --version prints out the current hsvm version.