Quick `make` guide for GHC

For a "Getting Started" guide, see:

Common commands:

make

Builds everything: ghc stages 1 and 2, all libraries and tools.
make -j2

Parallel build: runs up to 2 commands at a time.
cd <dir>; make

Builds everything in the given directory.
cd <dir>; make help

Shows the targets available in
make install
make install-strip

Installs GHC, libraries and tools under $(prefix). The install-strip variant strips executable files while installing them.
make sdist
make binary-dist

Builds a source or binary distribution respectively
make show VALUE=<var>
make show! VALUE=<var>

Show the value of make variable . The show! variant works right after ./configure (it skips reading package-data.mk files).
make clean
make distclean
make maintainer-clean

Various levels of cleaning: "clean" restores the tree to the state after "./configure", "distclean" restores to the state after "python3 boot", and maintainer-clean restores the tree to the completely clean checked-out state.

Using `make` in subdirectories

make

Builds everything in this directory (including dependencies elsewhere in the tree, if necessary)
make fast

The same as 'make', but omits some phases and does not recalculate dependencies. Useful for saving time if you are sure the rest of the tree is up to date.
make clean
make distclean
make maintainer-clean

Clean just this directory
make html
make pdf
make ps

Make documentation in this directory (if any)
make show VALUE=<var>
make show! VALUE=<var>

Show the value of make variable . The show! variant works right after ./configure (it skips reading package-data.mk files).
make <file>

Bring a particular file up to date, e.g. make dist/build/Module.o The name is relative to the current directory