Problem Statement

Given   M   as a list of items and another list   N   of items chosen from   M,   create   M'   as a list with the first occurrences of items from   N   sorted to be in one of the set of indices of their original occurrence in   M   but in the order given by their order in   N. That is, items in   N   are taken from   M   without replacement, then the corresponding positions in   M'   are filled by successive items from   N.

The words not in   N   are left in their original positions.

If there are duplications then only the first instances in   M   up to as many as are mentioned in   N   are potentially re-ordered.

Is ordered as:

Show the output, here, for at least the following inputs:

Let's start with the solution:

orderDisjoint: function [m,n][
    ms: split.words m
    ns: split.words n

    indexes: new []

    loop ns 'item [
        idx: index ms item
        unless null? idx [
            'indexes ++ idx
            ms\[idx]: ""
        ]
    ]
    sort 'indexes

    loop.with:'i indexes 'idx ->
        ms\[idx]: ns\[i]
    
    return join.with:" " ms
]

process: function [a,b][
    print [a "|" b "->" orderDisjoint a b]
]

process "the cat sat on the mat" "mat cat"
process "the cat sat on the mat" "cat mat"
process "A B C A B C A B C" "C A C A"
process "A B C A B D A B E" "E A D A"
process "A B" "B"
process "A B" "B A"
process "A B B A" "B A"