Trither
Very simple implementations of Try, Either, and Option inspired by Scala. Depends on contracts.ruby. Disable contracts in production by setting the NO_CONTRACTS environment variable.
Installation
Add this line to your application's Gemfile:
gem 'trither'And then execute:
$ bundle
Or install it yourself as:
$ gem install trither
API
Factory methods
Try.make { computation }
If computation raises an error => Failure(error)
If computation returns without raising an error => Success(result)
Option.make(value)
If value.nil? => None
Else => Some(value)
Try (Success of Failure) methods
failure? Failure(error) => true
Success(value) => false
filter Failure(error) => Failure(error)
Success(value) => executes given block
if block's result is true => Success(value)
else => Failure(None)
flat_map Failure(error) => Failure(error)
Success(value) => executes given block and returns result
map Failure(error) => Failure(error)
Success(value) => executes given block & returns Success(result)
fail_map Failure(error) => executes given block & returns Failure(result)
Success(value) => Success(value)
or_else Failure(error) => executes given block and returns result
Success(value) => Success(value)
get_or_else Failure(error) => executes given block and returns result
Success(value) => returns the value
Either (Left or Right) methods
left? Left(value) => true
Right(value) => false
right? Left(value) => false
Right(value) => true
left returns value; defined on Left only
right returns value; defined on Right only
left_map Left(value) => executes given block and returns Left(result)
Right(value) => Right(value)
right_map Left(value) => Left(value)
Right(value) => executes given block and returns Right(result)
Option (Some or None) methods
empty? None => true
Some(value) => false
filter None => None
Some(value) => executes given block
if block's result is true => Some(value)
else => None
fetch None => returns default
Some(value) => returns value
flat_map None => returns None
Some(value) => executes given block
if block's result is nil => None
else => block's result
map None => returns None
Some(value) => executes given block and wraps result in Option
or_else None => executes given block and returns result
Some(value) => returns Some(value)
get_or_else None => executes given block and returns result
Some(value) => returns value
Usage
See usage.rb.
Development
After checking out the repo, run bundle install to install dependencies.
Then, run rake spec to run the tests.
To install this gem onto your local machine, run bundle exec rake install.
To release a new version, update the version number in version.rb, and then
run bundle exec rake release, which will create a git tag for the version,
push git commits and tags, and push the .gem file to
rubygems.org.
Contributing
Bug reports and pull requests are welcome on GitHub at https://github.com/lj-ditrapani/trither.
License
The gem is available as open source under the terms of the MIT License.
TODO
ADT?