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local functional = {}
---@generic T : string
---@param values T[]
---@return table<T, T>
function functional.enum(values)
local result = {}
for i = 1, #values do
local v = values[i]
result[v] = v
end
return result
end
---@generic T
---@param list T[]
---@return table<T, boolean>
function functional.set_of(list)
local set = {}
for i = 1, #list do
set[list[i]] = true
end
return set
end
---@generic T
---@param list T[]
---@return T[]
function functional.list_reverse(list)
local result = {}
for i = #list, 1, -1 do
result[#result + 1] = list[i]
end
return result
end
---@generic T, U
---@param fn fun(item: T): U
---@param list T[]
---@return U[]
function functional.list_map(fn, list)
local result = {}
for i = 1, #list do
result[#result + 1] = fn(list[i], i)
end
return result
end
function functional.table_pack(...)
return { n = select("#", ...), ... }
end
function functional.list_not_nil(...)
local result = {}
local args = functional.table_pack(...)
for i = 1, args.n do
if args[i] ~= nil then
result[#result + 1] = args[i]
end
end
return result
end
function functional.when(condition, value)
return condition and value or nil
end
function functional.lazy_when(condition, fn)
return condition and fn() or nil
end
function functional.coalesce(...)
local args = functional.table_pack(...)
for i = 1, args.n do
local variable = args[i]
if variable ~= nil then
return variable
end
end
end
---@generic T
---@param list T[]
---@return T[] @A shallow copy of the list.
function functional.list_copy(list)
local result = {}
for i = 1, #list do
result[#result + 1] = list[i]
end
return result
end
---@generic T
---@param predicate fun(item: T): boolean
---@param list T[]
---@return T | nil
function functional.list_find_first(predicate, list)
local result
for i = 1, #list do
local entry = list[i]
if predicate(entry) then
return entry
end
end
return result
end
---@generic T
---@param predicate fun(item: T): boolean
---@param list T[]
---@return boolean
function functional.list_any(predicate, list)
for i = 1, #list do
if predicate(list[i]) then
return true
end
end
return false
end
function functional.identity(a)
return a
end
function functional.always(a)
return function()
return a
end
end
---@generic T : fun(...)
---@param fn T
---@param cache_key_generator (fun(...): string | nil)|nil
---@return T
function functional.memoize(fn, cache_key_generator)
cache_key_generator = cache_key_generator or functional.identity
local cache = {}
return function(...)
local key = cache_key_generator(...)
if not cache[key] then
cache[key] = functional.table_pack(fn(...))
end
return unpack(cache[key], 1, cache[key].n)
end
end
---@generic T
---@param fn fun(): T
---@return fun(): T
function functional.lazy(fn)
local memoized = functional.memoize(fn, functional.always "lazyval")
return function()
return memoized()
end
end
---@generic T
---@param fn fun(...): T
---@return fun(...): T
function functional.partial(fn, ...)
local bound_args = functional.table_pack(...)
return function(...)
local args = functional.table_pack(...)
local merged_args = {}
for i = 1, bound_args.n do
merged_args[i] = bound_args[i]
end
for i = 1, args.n do
merged_args[bound_args.n + i] = args[i]
end
return fn(unpack(merged_args, 1, bound_args.n + args.n))
end
end
function functional.compose(...)
local functions = functional.table_pack(...)
assert(functions.n > 0, "compose requires at least one function")
return function(...)
local result = functional.table_pack(...)
for i = functions.n, 1, -1 do
result = functional.table_pack(functions[i](unpack(result, 1, result.n)))
end
return unpack(result, 1, result.n)
end
end
---@generic T
---@param filter_fn fun(item: T): boolean
---@return fun(list: T[]): T[]
function functional.filter(filter_fn)
return functional.partial(vim.tbl_filter, filter_fn)
end
function functional.each(fn, list)
for k, v in pairs(list) do
fn(v, k)
end
end
return functional
|
