LÖVE

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for(int i=p*p;i>j;j*=p) {
    //some code here
}

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local i = p*p
while i>j do
   --some code here
   j*=p
end

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function multiply(start, stop, step)
  return function()
        start = start * step
        if start < stop then -- I assume you meant this
            return start
        end
   end
end

for i in multiply(p, j, p) do
  -- some code here
end

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function m(p,j) return p*p > j and j * p or nil end
for j in m, <p>, <j> do -- you could replace m with an anonymous function here
    -- some code
end

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for key, value in pairs(tbl) do --[[ stuff --]] end

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for (std::map<key_type, value_type>::iterator it = tbl.begin(); it != tbl.end(); ++it) {
    key_type &key = it->first;
    value_type &value = it->second;
    // stuff
}

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file = assert(io.open(<filename>, 'r'))
for line in file:lines() do --[[ stuff --]] end

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std::ifstream file(<filename>);
assert(file.good());
for (std::string line; getline(file, line); /*nothing*/) { /* stuff */ }

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# tbl is an array
tbl.each do |v|
...
end

# tbl is a hash
tbl.each do |k,v|
...
end

#one-liners
tbl.each {|v| ... } #array
tbl.each {|k,v| ... } #hash

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function map(func, tbl)
    local out = {}
    for k,v in pairs(tbl) out[k] = func(v, k)
    return out
end
map(function(x) return x*x end, {1,2,3,4,5,6}) --> {1, 4, 9, 16, 25, 36}

function filter(pred, tbl)
    local out = {}
    for k,v in pairs(tbl) do if pred(v,k) out[k] = v end end
    return out
end
filter(function(x) return x%2 == 0 end, {1,2,3,4,5,6}) --> {2, 4, 6}

function fold(func, init, tbl)
    for k,v in pairs(tbl) do init = func(init, v,k) end
    return init
end
fold(function(a, x) return a+x end, 0, {1,2,3,4,5,6}) --> 21

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(loop for i in my-list (do-stuff i))  ; iterate over a list

(loop for k being the hask-keys in my-hash using (hash-value v) ; iterate over a hash
     (do-stuff k v))

(loop for num in my-numbers   ; do all kinds of stuff over a list: 
     collecting (evenp num) into evens  ; filter by a condition
     counting t into count   ; count by a contition (always true here)
     summing num into sum
     maximizing num into max
     minimizing num into min
     finally (return (list :count count :evens evens :sum sum :mean (/ sum count) :min min :max max)))

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IO.foreach('filename.txt') { |line| puts line }

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IO.foreach('filename.txt') do |line|
  # ...
end

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-- take the first argument, remove all quotes, split words into an array, capitalize each word, join them back together into a string
ARGV[0].gsub(/'|"/, '').split.map {|v| v.capitalize }.join
-- generates a random 7 character strings with characters from 0-z
('0'..'z').to_a.shuffle[0..7].join