functional.lua

Defines F, a namespace for several list functions:

• F.count(obj)
• F.range(min, max, step)
• F.map(obj, func, f_pairs)
• F.reduce(obj, seed, func, f_ipairs)
• F.any(obj, func, f_pairs)
• F.all(obj, func, f_pairs)
• F.none(obj, func, f_pairs)
• F.filter(obj, func, f_pairs)
• F.slice(obj, start, _end, f_ipairs)
• F.bind(func, ...)
• F.id(...)
• F.index(ix)
• F.index_into(obj)
• F.foreach(obj, func, f_pairs)
• F.merge(a, b, f_pairs_a, f_pairs_b)
• F.concat(a, b, f_ipairs_a, f_ipairs_b)
• F.keys(table, f_pairs)
• F.values(table, f_pairs)
• F.entries(table, f_pairs)

Fluent mode

Defines syntax for fluent queries:

• F.pairs(obj)
• F.ipairs(obj)
• F.from(obj, f_pairs, numeric)
• F.from_range(start, _end, step)
• F.q_concat(a, b)
• q:map(func)
• q:filter(func)
• q:flatmap(func)
• q:take(n)
• q:skip(n)
• q:keys()
• q:values()
• q:entries()
• q:sorted(func)
• q:append(other)
• q:prepend(other)
• q:join(other, func)
• q:zip(other, func)
• q:foreach(func)
• q:reduce(seed, func)
• q:count(func)
• q:conjoin(separator)
• q:tostring()
• q:into()
• q:pairs()
• q:any()
• q:all()
• q:unordered()
• q:ordered()
• q.next()
• q.numeric

Example usage

for k, v in 
    F.from_range(1, 10) -- Query the integers from 1 to 10
    :map(function(x) return x * x end) -- Square them
    :filter(function(x) return x >= 20 end) -- Discard any squares less than 20
    :pairs() -- Iterate over the query
do
    print(k, v)
end

local things = {
    c = 3,
    b = 2,
    a = 1,
    d = 4
}
-- `stuff` is a list of the keys of `things` sorted by their respective values
local stuff = F.pairs(things) -- Query `things`
    :sorted(function(a, b) return a < b end) -- Sort the query with the given function
    :entries() -- Start working on key-value pairs
    :map(F.index(1)) -- Select the keys from those key-value pairs (`:map(F.index('k'))` would do the same)
    :into() -- Turn the result into a table
for _, v in ipairs(stuff) do
    print(v)
end