Rebol3 Code Examplex

Rebol [
    title: "Rosetta code: Semordnilap"
    file: %Semordnilap.r3
    url: https://rosettacode.org/wiki/Semordnilap
    needs: 3.14.0
]
system/options/quiet: true

file: %unixdict.txt
unless exists? file [
    print "Downloading wordlist."
    write file read http://wiki.puzzlers.org/pub/wordlists/unixdict.txt
]
words: read/lines file 
seen: make map! 200
count: 0

print reform ["Number of input words:" length? words LF]

foreach word words [
    reversed: reverse copy word
    either find seen reversed [
        if ++ count <= 5 [
            printf [-10 " - " 10] reduce [word reversed]
        ]
    ][
        put seen word reversed
    ]
]

print [LF "Found total" as-yellow count "semordnilap pairs."]