ruby - How to distribute a conditional through an n-dimensional array -

[a, b].fetch(x) notionally equivalent following method:

def fetch(x)   if x == 0       elsif x == 1     b   end end 

this generalises, e.g. [[a, b], [c, d]].fetch(x) equivalent to:

def fetch(x)   if x == 0     [a, b]   elsif x == 1     [c, d]   end end 

which equivalent to:

def fetch(x)   [     if x == 0           elsif x == 1       c     end,     if x == 0       b     elsif x == 1       d     end   ] end 

in case, conditional has been distributed each of elements within array.

if have n-dimensional array, how can dynamically define #fetch(x) array:

def define_fetch(some_array)   define_method :fetch |x|     # ???   end end  define_fetch([[[a, b], [c, d]], [[e, f], [g, h]]]) 

i'm interested in latter example conditionals distributed within each of resulting array's elements.