Lakefile (lake is logical make, a reimplementation of make built around the concept that make is really just a constructive logic programming language).

Makefile

# Traditional Makefile style: (different wildcard symbol)
# \forall_{$} $.c -> $.o
*.o: *.c
	gcc -c $.c -o $.o
	
# From and to variables:
# Using $^ (from) and $v (to)
*.o: *.c
	gcc -c $^ -o $v

# Multi-wildcard rule:
# This will generate a rule for every architecture-specific file. e.g.
#
# 	fs.o: os/win32/fs.c
#	fs.o: os/macos/fs.c
#	fs.o: os/linux/fs.c
#
# The build system will apply the BFINAE (build failure is not an error)
# rule to disambiguate. You should ensure only one of those three files will
# successfully build on a given platform. 
# What is special here is not really multiple wildcards, but not requiring every
# universally quantified variable to be in the target.
# \forall_{$1} \forall_{$2} os/$2/$1.c -> $1.o
$1.o: os/$2/$1.c
	gcc -c $^ -o $v

# Strict dependencies: (!-rule)
# The ! modifier creates a strict dependency, so this rule is only in effect
# if $.bib has changed, while the normal behaviour is that if *any* dependency
# has changed the file will be rebuilt.
# A numbered wildcard can use $!n instead of $n.
*.bbl: *.ltx !*.bib
	bibtex $.ltx

# Fixed points:
# A rule where a file appears before and after the colon will be run
# until it reaches a fixed-point for all of its targets. 
*.pdf *.aux *.bbl: *.ltx *.aux *.bbl
	pdflatex $.ltx
	
# Dependency-generating rule: (@-rule)
# This will run the given command, and its standard output should be
# a set of dependencies that anything that depends on this file should
# also depend upon.
# Note: **/*.c doesn't mean '$1$1/$1.c', it means '$1.c|$2/$1.c|$3/$2/$1.c|...'. 
@**/*.c:
	sed -n 's/#include "\(.*\)"/\1/p' $^