sw-examples: expand-srange.sw3

-- a useful operator, the expand-srange operator:
-- Given |one .. two>, return srange(one, two).
-- Given |one .. two .. step>, return srange(one, two, step).
-- If one and two have categories defined, then so does the result.
-- If their categories don't match, return the ket unchanged.
-- If the given ket is not a valid range, or a badly defined range, then return it unchanged.
-- The same structure can be used for other functions, not just srange().
-- Eg, range().


-- examples:
-- expand-srange |3 .. 7>
--     |3> . |4> . |5> . |6> . |7>
--
-- expand-srange |number: 8 .. |number: 11>
--     |number: 8> . |number: 9> . |number: 10> . |number: 11>
--
-- expand-srange |3 .. 9 .. 2>
--     |3> . |5> . |7> . |9>
--
-- expand-srange |alpha>
--     |alpha>
--
-- expand-srange |alpha .. 11>
--     |alpha .. 11>
--


expand-srange |*> #=>
    unlearn[the] |result>
    the |result> => compile (|op: srange> . |> . ssplit[" .. "] |__self>)
    value-if( do-you-know the |result>, the |result>, |__self>)

expand-range |*> #=>
    unlearn[the] |result>
    the |result> => compile (|op: range> . |> . ssplit[" .. "] |__self>)
    value-if( do-you-know the |result>, the |result>, |__self>)