How to replace words in file with dictionary and save it to the file?

Question

A have a dictionary as

dict = { 
    body = "Körper",
    child = "Kind",
    eye = "Auge"
    face = "Gesicht"
}

And I have something like lookup function as:

function performLookup(words, dict)
    for i, word in ipairs(words) do
        if dict[word] then
            words[i] = dict[word]
        end
    end
end

How to open the file, find the line (one line has just one word) and save it to other file? Ideally the dictionary must be also in the file and loaded as lookup table.

Update: So, by having files dict.tsv and locale_EN.txt we creating a new locale file, but with accordingly replaced words in the file locale_DE.txt.

Answer 1

(Updated with question edit)

function performLookup(words, dict)
    for i, word in ipairs(words) do
        if dict[word] then
            words[i] = dict[word]
        end
    end
end

function readDict(fname)
    local dict = {}
    local file = io.open(fname, "r")
    for line in file:lines() do
        local english, german = line:match("(%S+)%s+(%S+)")
        -- or \t instead of %s+ for single tab, or \t+ if multiple tabs allowed
        dict[english] = german
    end
    file:close()
    return dict
end

function readInput(fname)
    local words = {}
    local file = io.open(fname, "r")
    for line in file:lines() do
        table.insert(words, line)
    end
    file:close()
    return words
end

function writeFile(fname, dict, words)
    file = io.open(fname, "w")
    performLookup(words, dict)
    for i, line in ipairs(words) do
        file:write((i == 1 and "" or "\n") .. line) 
    end
    file:close()
end

dict = readDict("dict.tsv")
words = readInput("locale_EN.txt")
writeFile("locale_DE.txt", dict, words)

The input file (locale_EN.txt) looks like:

some
random
words
eye
and
a
few
more
face

The output file (locale_DE.txt) looks like:

some
random
words
Auge
and
a
few
more
Gesicht

The dictionary (dict.tsv) looks like:

body    Körper
child   Kind
eye Auge
face    Gesicht

The question could have better clarity but is this what you are looking for? Would need some error checking too, since it assumes correct format.