How to make user defined function descriptions (“docstrings”) available to julia REPL?

Question

How can user defined functions (say f) have meaningful printouts when inspected via the REPL using ?for help(f)

For example imagin

Answer 1

In Julia v0.5+ (including more recent Julia Versions like 1.2+), you can write a multiline string above the function definition. (No need for @doc anymore.)

julia> """
           cube(x)

       Compute the cube of `x`, ``x^3``.

       # Examples
       ```jldoctest
       julia> cube(2)
       8
       ```
       """
       function cube(x)
           x^3
       end
cube

help?> cube
search: Cdouble isexecutable Ac_mul_B Ac_mul_Bc Ac_mul_B! Ac_mul_Bc! cumsum_kbn

  cube(x)

  Compute the cube of x, x^3.

     Examples
    ≡≡≡≡≡≡≡≡≡≡

  julia> cube(2)
  8

For more information on properly formatting your docstrings, see the official Julia Documentation.