Calculating with functions

_readme.md

Calculating with Functions

Solutions to the Calculating with Functions CodeWars kata.

brute-force.rb

# My first take on it. Dumb, repetitive, and probably slow, but it gets the job done.

def zero(*v)
  eval [ 0, *v ].join
end

def one(*v)
  eval [ 1.0, *v ].join
end

def two(*v)
  eval [ 2.0, *v ].join
end

def three(*v)
  eval [ 3.0, *v ].join
end

def four(*v)
  eval [ 4.0, *v ].join
end

def five(*v)
  eval [ 5.0, *v ].join
end

def six(*v)
  eval [ 6.0, *v ].join
end

def seven(*v)
  eval [ 7.0, *v ].join
end

def eight(*v)
  eval [ 8.0, *v ].join
end

def nine(*v)
  eval [ 9.0, *v ].join
end

def plus(v)
  [ "+", *v ]
end

def minus(v)
  [ "-", *v ]
end

def times(v)
  [ "*", *v ]
end

def divided_by(v)
  [ "/", *v ]
end

more-elegant.rb

# A second go in which I eliminate the repetition and try to get fancy with lambdas.

def number_generator(number)
  ->(operation = [ :to_f ]) { number.send(*operation) }
end

%w[ zero one two three four five six seven eight nine ].each_with_index do |name, index|
  define_method(name, &number_generator(index))
end

def operator_generator(operator)
  ->(rhs) { [ operator, *rhs ] }
end

%w[ plus + minus - times * divided_by / ].each_slice(2) do |name, operator|
  define_method(name, &operator_generator(operator))
end

terse.rb

# The lambda thing was kinda fun, but didn't solve the problem any better than a more 
# prosaic solution and was a lot harder to understand.

%i[ zero one two three four five six seven eight nine ].each_with_index do |name, number|
  define_method(name) do |operation = [ :to_f ]|
    number.send(*operation)
  end
end

%i[ plus + minus - times * divided_by / ].each_slice(2) do |name, operator|
  define_method(name) do |rhs|
    [ operator, *rhs ]
  end
end