target: "METHINKS IT IS LIKE A WEASEL"
alphabet: [` `] ++ @`A`..`Z`
p: 0.05
c: 100


negFitness: function [trial][
    result: 0
    loop 0..dec size trial 'i ->
        if target\[i] <> trial\[i] -> inc 'result
    return result
]

mutate: function [parent][
    result: ""
    loop parent 'c ->
        'result ++ (p > random 0.0 1.0)? -> sample alphabet -> c
    return result
]

parent: ""
do.times: size target ->
    'parent ++ sample alphabet

j: 0

copies: []
while [parent <> target][
    'copies ++ map c 'i -> mutate parent

    best: first copies
    loop 1..dec size copies 'i [
        if (negFitness copies\[i]) < negFitness best ->
            best: copies\[i]
    ]
    parent: best

    print [pad to :string j 2 parent]
    inc 'j
]