Universality in Mathematica

As an example of how different primitive operations can be used to do the same computation, the following are a few ways that the factorial function can be defined in Mathematica:

f[n_] := n!

f[n_] := n f[n - 1]; f[1] = 1

f[n_] := Product[i, {i, n}]

f[n_] := Module[{t = 1}, Do[t = t i, {i, n}]; t]

f[n_] := Module[{t = 1, i}, For[i = 1, i ≤ n, i++, t ⋆= i]; t]

f[n_] := Apply[Times, Range[n]]

f[n_] := Fold[Times, 1, Range[n]]

f[n_] := If[n  1, 1, n f[n - 1]]

f[n_] := Fold[#2[#1] &, 1, Array[Function[t, # t] &, n]]

f = If[#1  1, 1, #1 #0[#1 - 1]] &