1 files changed, 89 insertions, 0 deletions
diff --git a/lua/mason-core/functional/function.lua b/lua/mason-core/functional/function.lua
new file mode 100644
index 00000000..e85081ce
--- /dev/null
+++ b/lua/mason-core/functional/function.lua
@@ -0,0 +1,89 @@
+local data = require "mason-core.functional.data"
+
+local _ = {}
+
+---@generic T : fun(...)
+---@param fn T
+---@param arity integer
+---@return T
+_.curryN = function(fn, arity)
+    return function(...)
+        local args = data.table_pack(...)
+        if args.n >= arity then
+            return fn(unpack(args, 1, arity))
+        else
+            return _.curryN(_.partial(fn, unpack(args, 1, args.n)), arity - args.n)
+        end
+    end
+end
+
+_.compose = function(...)
+    local functions = data.table_pack(...)
+    assert(functions.n > 0, "compose requires at least one function")
+    return function(...)
+        local result = data.table_pack(...)
+        for i = functions.n, 1, -1 do
+            result = data.table_pack(functions[i](unpack(result, 1, result.n)))
+        end
+        return unpack(result, 1, result.n)
+    end
+end
+
+---@generic T
+---@param fn fun(...): T
+---@return fun(...): T
+_.partial = function(fn, ...)
+    local bound_args = data.table_pack(...)
+    return function(...)
+        local args = data.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
+
+_.identity = function(a)
+    return a
+end
+
+_.always = function(a)
+    return function()
+        return a
+    end
+end
+
+_.T = _.always(true)
+_.F = _.always(false)
+
+---@generic T : fun(...)
+---@param fn T
+---@param cache_key_generator (fun(...): string | nil)|nil
+---@return T
+_.memoize = function(fn, cache_key_generator)
+    cache_key_generator = cache_key_generator or _.identity
+    local cache = {}
+    return function(...)
+        local key = cache_key_generator(...)
+        if not cache[key] then
+            cache[key] = data.table_pack(fn(...))
+        end
+        return unpack(cache[key], 1, cache[key].n)
+    end
+end
+
+---@generic T
+---@param fn fun(): T
+---@return fun(): T
+_.lazy = function(fn)
+    local memoized = _.memoize(fn, _.always "lazyval")
+    return function()
+        return memoized()
+    end
+end
+
+return _