Question

Given an array of lambdas and an array of values (both created at run time),

values.map{ |value| lambdas[0].(value) }

would (obviously) return as an array the result of applying the first of the lambdas to each of the values. But what I need to do is apply all of the lambdas, i.e. the equivalent of

values.
  map{ |value| lambdas[0].(value) }.
  map{ |value| lambdas[1].(value) }.
  ...
  map{ |value| lambdas[-1].(value) }

I can certainly write a method to do so, e.g.

def map_all(lambdas, values)
  if lambdas.length == 0
    values
  else
    map_all(lambdas.drop(1), values.map{ |value| lambdas.first.(value) })
  end
end

but is there a more elegant or idiomatic way to do this?

Answer 1

Sure, here you go:

values.map { |value| lambdas.inject(value) { |v,l| l.(v) } }