Answers to the question: Does (-1%7) resolve to -1 or 6?

glass-half-empty.sh

$ node --version
v5.6.0
$ node -e "console.log(-1 % 7)"
-1

$ bc --version
bc 1.06
Copyright 1991-1994, 1997, 1998, 2000 Free Software Foundation, Inc.
$ echo "-1 % 7 "| bc
-1

$ go version
go version go1.5 darwin/amd64
$ echo 'package main; import "fmt"; func main() { fmt.Println(-1 % 7) }' > /tmp/glass-test.go
$ go run /tmp/glass-test.go
-1

$ g++ --version | grep version
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 7.0.2 (clang-700.1.81)
$ echo -e '#include <iostream>\nint main() { std::cout << -1 % 7 << std::endl; }' > /tmp/glass-test.cpp
$ g++ -o /tmp/glass-test.out /tmp/glass-test.cpp 
$ /tmp/glass-test.out 
-1

glass-has-a-remainder.rb

$ ruby --version
ruby 2.3.1p112 (2016-04-26 revision 54768) [x86_64-darwin14]
$ ruby -e "puts -1 % 7"
6

$ python --version
Python 2.7.10
$ python -c "print -1 % 7"
6

$ perl --version | grep version
This is perl 5, version 18, subversion 2 (v5.18.2) built for darwin-thread-multi-2level
$ perl -e "print -1 % 7"
6

$ crystal --version
Crystal 0.18.7 (2016-08-05)
$ crystal eval 'puts -1 % 7'
6