10 files changed, 653 insertions, 0 deletions
diff --git a/lua/mason-core/functional/data.lua b/lua/mason-core/functional/data.lua
new file mode 100644
index 00000000..da6f1efd
--- /dev/null
+++ b/lua/mason-core/functional/data.lua
@@ -0,0 +1,30 @@
+local _ = {}
+
+_.table_pack = function(...)
+    return { n = select("#", ...), ... }
+end
+
+---@generic T : string
+---@param values T[]
+---@return table<T, T>
+_.enum = function(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>
+_.set_of = function(list)
+    local set = {}
+    for i = 1, #list do
+        set[list[i]] = true
+    end
+    return set
+end
+
+return _
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 _
diff --git a/lua/mason-core/functional/init.lua b/lua/mason-core/functional/init.lua
new file mode 100644
index 00000000..a7b0a369
--- /dev/null
+++ b/lua/mason-core/functional/init.lua
@@ -0,0 +1,112 @@
+local _ = {}
+
+-- data
+local data = require "mason-core.functional.data"
+_.table_pack = data.table_pack
+_.enum = data.enum
+_.set_of = data.set_of
+
+-- function
+local fun = require "mason-core.functional.function"
+_.curryN = fun.curryN
+_.compose = fun.compose
+_.partial = fun.partial
+_.identity = fun.identity
+_.always = fun.always
+_.T = fun.T
+_.F = fun.F
+_.memoize = fun.memoize
+_.lazy = fun.lazy
+
+-- list
+local list = require "mason-core.functional.list"
+_.reverse = list.reverse
+_.list_not_nil = list.list_not_nil
+_.list_copy = list.list_copy
+_.find_first = list.find_first
+_.any = list.any
+_.filter = list.filter
+_.map = list.map
+_.filter_map = list.filter_map
+_.each = list.each
+_.concat = list.concat
+_.append = list.append
+_.prepend = list.prepend
+_.zip_table = list.zip_table
+_.nth = list.nth
+_.head = list.head
+_.length = list.length
+_.flatten = list.flatten
+_.sort_by = list.sort_by
+_.join = list.join
+
+-- relation
+local relation = require "mason-core.functional.relation"
+_.equals = relation.equals
+_.prop_eq = relation.prop_eq
+_.prop_satisfies = relation.prop_satisfies
+
+-- logic
+local logic = require "mason-core.functional.logic"
+_.all_pass = logic.all_pass
+_.any_pass = logic.any_pass
+_.if_else = logic.if_else
+_.is_not = logic.is_not
+_.complement = logic.complement
+_.cond = logic.cond
+
+-- number
+local number = require "mason-core.functional.number"
+_.negate = number.negate
+_.gt = number.gt
+_.gte = number.gte
+_.lt = number.lt
+_.lte = number.lte
+_.inc = number.inc
+_.dec = number.dec
+
+-- string
+local string = require "mason-core.functional.string"
+_.matches = string.matches
+_.format = string.format
+_.split = string.split
+_.gsub = string.gsub
+_.trim = string.trim
+_.dedent = string.dedent
+_.starts_with = string.starts_with
+
+-- table
+local tbl = require "mason-core.functional.table"
+_.prop = tbl.prop
+_.pick = tbl.pick
+_.keys = tbl.keys
+_.size = tbl.size
+_.to_pairs = tbl.to_pairs
+_.invert = tbl.invert
+
+-- type
+local typ = require "mason-core.functional.type"
+_.is_nil = typ.is_nil
+_.is = typ.is
+
+-- TODO do something else with these
+
+_.coalesce = function(...)
+    local args = _.table_pack(...)
+    for i = 1, args.n do
+        local variable = args[i]
+        if variable ~= nil then
+            return variable
+        end
+    end
+end
+
+_.when = function(condition, value)
+    return condition and value or nil
+end
+
+_.lazy_when = function(condition, value)
+    return condition and value() or nil
+end
+
+return _
diff --git a/lua/mason-core/functional/list.lua b/lua/mason-core/functional/list.lua
new file mode 100644
index 00000000..14db386e
--- /dev/null
+++ b/lua/mason-core/functional/list.lua
@@ -0,0 +1,175 @@
+local fun = require "mason-core.functional.function"
+local data = require "mason-core.functional.data"
+
+local _ = {}
+
+---@generic T
+---@param list T[]
+---@return T[]
+_.reverse = function(list)
+    local result = {}
+    for i = #list, 1, -1 do
+        result[#result + 1] = list[i]
+    end
+    return result
+end
+
+_.list_not_nil = function(...)
+    local result = {}
+    local args = data.table_pack(...)
+    for i = 1, args.n do
+        if args[i] ~= nil then
+            result[#result + 1] = args[i]
+        end
+    end
+    return result
+end
+
+---@generic T
+---@param predicate fun(item: T): boolean
+---@param list T[]
+---@return T | nil
+_.find_first = fun.curryN(function(predicate, list)
+    local result
+    for i = 1, #list do
+        local entry = list[i]
+        if predicate(entry) then
+            return entry
+        end
+    end
+    return result
+end, 2)
+
+---@generic T
+---@param predicate fun(item: T): boolean
+---@param list T[]
+---@return boolean
+_.any = fun.curryN(function(predicate, list)
+    for i = 1, #list do
+        if predicate(list[i]) then
+            return true
+        end
+    end
+    return false
+end, 2)
+
+---@generic T
+---@type fun(filter_fn: (fun(item: T): boolean), items: T[]): T[]
+_.filter = fun.curryN(vim.tbl_filter, 2)
+
+---@generic T, U
+---@type fun(map_fn: (fun(item: T): U), items: T[]): U[]
+_.map = fun.curryN(vim.tbl_map, 2)
+
+_.flatten = fun.curryN(vim.tbl_flatten, 1)
+
+---@generic T
+---@param map_fn fun(item: T): Optional
+---@param list T[]
+---@return any[]
+_.filter_map = fun.curryN(function(map_fn, list)
+    local ret = {}
+    for i = 1, #list do
+        map_fn(list[i]):if_present(function(value)
+            ret[#ret + 1] = value
+        end)
+    end
+    return ret
+end, 2)
+
+---@generic T
+---@param fn fun(item: T, index: integer)
+---@param list T[]
+_.each = fun.curryN(function(fn, list)
+    for k, v in pairs(list) do
+        fn(v, k)
+    end
+end, 2)
+
+---@generic T
+---@param list T[]
+---@return T[] @A shallow copy of the list.
+_.list_copy = _.map(fun.identity)
+
+_.concat = fun.curryN(function(a, b)
+    if type(a) == "table" then
+        assert(type(b) == "table", "concat: expected table")
+        return vim.list_extend(_.list_copy(a), b)
+    elseif type(a) == "string" then
+        assert(type(b) == "string", "concat: expected string")
+        return a .. b
+    end
+end, 2)
+
+---@generic T
+---@param value T
+---@param list T[]
+---@return T[]
+_.append = fun.curryN(function(value, list)
+    local list_copy = _.list_copy(list)
+    list_copy[#list_copy + 1] = value
+    return list_copy
+end, 2)
+
+---@generic T
+---@param value T
+---@param list T[]
+---@return T[]
+_.prepend = fun.curryN(function(value, list)
+    local list_copy = _.list_copy(list)
+    table.insert(list_copy, 1, value)
+    return list_copy
+end, 2)
+
+---@generic T
+---@generic U
+---@param keys T[]
+---@param values U[]
+---@return table<T, U>
+_.zip_table = fun.curryN(function(keys, values)
+    local res = {}
+    for i, key in ipairs(keys) do
+        res[key] = values[i]
+    end
+    return res
+end, 2)
+
+---@generic T
+---@param offset number
+---@param value T[]|string
+---@return T|string|nil
+_.nth = fun.curryN(function(offset, value)
+    local index = offset < 0 and (#value + (offset + 1)) or offset
+    if type(value) == "string" then
+        return string.sub(value, index, index)
+    else
+        return value[index]
+    end
+end, 2)
+
+_.head = _.nth(1)
+
+---@param value string|any[]
+_.length = function(value)
+    return #value
+end
+
+---@generic T
+---@param comp fun(item: T): any
+---@param list T[]
+---@return T[]
+_.sort_by = fun.curryN(function(comp, list)
+    local copied_list = _.list_copy(list)
+    table.sort(copied_list, function(a, b)
+        return comp(a) < comp(b)
+    end)
+    return copied_list
+end, 2)
+
+---@param sep string
+---@param list any[]
+_.join = fun.curryN(function(sep, list)
+    return table.concat(list, sep)
+end, 2)
+
+return _
diff --git a/lua/mason-core/functional/logic.lua b/lua/mason-core/functional/logic.lua
new file mode 100644
index 00000000..0e0044d5
--- /dev/null
+++ b/lua/mason-core/functional/logic.lua
@@ -0,0 +1,63 @@
+local fun = require "mason-core.functional.function"
+
+local _ = {}
+
+---@generic T
+---@param predicates (fun(item: T): boolean)[]
+---@return fun(item: T): boolean
+_.all_pass = fun.curryN(function(predicates, item)
+    for i = 1, #predicates do
+        if not predicates[i](item) then
+            return false
+        end
+    end
+    return true
+end, 2)
+
+---@generic T
+---@param predicates (fun(item: T): boolean)[]
+---@return fun(item: T): boolean
+_.any_pass = fun.curryN(function(predicates, item)
+    for i = 1, #predicates do
+        if predicates[i](item) then
+            return true
+        end
+    end
+    return false
+end, 2)
+
+---@generic T
+---@param predicate fun(item: T): boolean
+---@param on_true fun(item: T): any
+---@param on_false fun(item: T): any
+---@param value T
+_.if_else = fun.curryN(function(predicate, on_true, on_false, value)
+    if predicate(value) then
+        return on_true(value)
+    else
+        return on_false(value)
+    end
+end, 4)
+
+---@param value boolean
+_.is_not = function(value)
+    return not value
+end
+
+---@generic T
+---@param predicate fun(value: T): boolean
+---@param value T
+_.complement = fun.curryN(function(predicate, value)
+    return not predicate(value)
+end, 2)
+
+_.cond = fun.curryN(function(predicate_transformer_pairs, value)
+    for _, pair in ipairs(predicate_transformer_pairs) do
+        local predicate, transformer = pair[1], pair[2]
+        if predicate(value) then
+            return transformer(value)
+        end
+    end
+end, 2)
+
+return _
diff --git a/lua/mason-core/functional/number.lua b/lua/mason-core/functional/number.lua
new file mode 100644
index 00000000..11e8f88a
--- /dev/null
+++ b/lua/mason-core/functional/number.lua
@@ -0,0 +1,34 @@
+local fun = require "mason-core.functional.function"
+
+local _ = {}
+
+---@param number number
+_.negate = function(number)
+    return -number
+end
+
+_.gt = fun.curryN(function(number, value)
+    return value > number
+end, 2)
+
+_.gte = fun.curryN(function(number, value)
+    return value >= number
+end, 2)
+
+_.lt = fun.curryN(function(number, value)
+    return value < number
+end, 2)
+
+_.lte = fun.curryN(function(number, value)
+    return value <= number
+end, 2)
+
+_.inc = fun.curryN(function(increment, value)
+    return value + increment
+end, 2)
+
+_.dec = fun.curryN(function(decrement, value)
+    return value - decrement
+end, 2)
+
+return _
diff --git a/lua/mason-core/functional/relation.lua b/lua/mason-core/functional/relation.lua
new file mode 100644
index 00000000..94913a13
--- /dev/null
+++ b/lua/mason-core/functional/relation.lua
@@ -0,0 +1,17 @@
+local fun = require "mason-core.functional.function"
+
+local _ = {}
+
+_.equals = fun.curryN(function(expected, value)
+    return value == expected
+end, 2)
+
+_.prop_eq = fun.curryN(function(property, value, tbl)
+    return tbl[property] == value
+end, 3)
+
+_.prop_satisfies = fun.curryN(function(predicate, property, tbl)
+    return predicate(tbl[property])
+end, 3)
+
+return _
diff --git a/lua/mason-core/functional/string.lua b/lua/mason-core/functional/string.lua
new file mode 100644
index 00000000..7726c8e1
--- /dev/null
+++ b/lua/mason-core/functional/string.lua
@@ -0,0 +1,74 @@
+local fun = require "mason-core.functional.function"
+
+local _ = {}
+
+---@param pattern string
+---@param str string
+_.matches = fun.curryN(function(pattern, str)
+    return str:match(pattern) ~= nil
+end, 2)
+
+---@param template string
+---@param str string
+_.format = fun.curryN(function(template, str)
+    return template:format(str)
+end, 2)
+
+---@param sep string
+---@param str string
+_.split = fun.curryN(function(sep, str)
+    return vim.split(str, sep)
+end, 2)
+
+---@param pattern string
+---@param repl string|function|table
+---@param str string
+_.gsub = fun.curryN(function(pattern, repl, str)
+    return string.gsub(str, pattern, repl)
+end, 3)
+
+_.trim = fun.curryN(function(str)
+    return vim.trim(str)
+end, 1)
+
+---https://github.com/nvim-lua/nvim-package-specification/blob/93475e47545b579fd20b6c5ce13c4163e7956046/lua/packspec/schema.lua#L8-L37
+---@param str string
+---@return string
+_.dedent = fun.curryN(function(str)
+    local lines = {}
+    local indent = nil
+
+    for line in str:gmatch "[^\n]*\n?" do
+        if indent == nil then
+            if not line:match "^%s*$" then
+                -- save pattern for indentation from the first non-empty line
+                indent, line = line:match "^(%s*)(.*)$"
+                indent = "^" .. indent .. "(.*)$"
+                table.insert(lines, line)
+            end
+        else
+            if line:match "^%s*$" then
+                -- replace empty lines with a single newline character.
+                -- empty lines are handled separately to allow the
+                -- closing "]]" to be one indentation level lower.
+                table.insert(lines, "\n")
+            else
+                -- strip indentation on non-empty lines
+                line = assert(line:match(indent), "inconsistent indentation")
+                table.insert(lines, line)
+            end
+        end
+    end
+
+    lines = table.concat(lines)
+    -- trim trailing whitespace
+    return lines:match "^(.-)%s*$"
+end, 1)
+
+---@param prefix string
+---@str string
+_.starts_with = fun.curryN(function(prefix, str)
+    return vim.startswith(str, prefix)
+end, 2)
+
+return _
diff --git a/lua/mason-core/functional/table.lua b/lua/mason-core/functional/table.lua
new file mode 100644
index 00000000..65d05cc8
--- /dev/null
+++ b/lua/mason-core/functional/table.lua
@@ -0,0 +1,45 @@
+local fun = require "mason-core.functional.function"
+
+local _ = {}
+
+---@param index any
+---@param tbl table
+_.prop = fun.curryN(function(index, tbl)
+    return tbl[index]
+end, 2)
+
+---@param keys any[]
+---@param tbl table
+_.pick = fun.curryN(function(keys, tbl)
+    local ret = {}
+    for _, key in ipairs(keys) do
+        ret[key] = tbl[key]
+    end
+    return ret
+end, 2)
+
+_.keys = fun.curryN(vim.tbl_keys, 1)
+_.size = fun.curryN(vim.tbl_count, 1)
+
+---@param tbl table<any, any>
+---@return any[][]
+_.to_pairs = fun.curryN(function(tbl)
+    local result = {}
+    for k, v in pairs(tbl) do
+        result[#result + 1] = { k, v }
+    end
+    return result
+end, 1)
+
+---@generic K, V
+---@param tbl table<K, V>
+---@return table<V, K>
+_.invert = fun.curryN(function(tbl)
+    local result = {}
+    for k, v in pairs(tbl) do
+        result[v] = k
+    end
+    return result
+end, 1)
+
+return _
diff --git a/lua/mason-core/functional/type.lua b/lua/mason-core/functional/type.lua
new file mode 100644
index 00000000..e3bf5fe7
--- /dev/null
+++ b/lua/mason-core/functional/type.lua
@@ -0,0 +1,14 @@
+local fun = require "mason-core.functional.function"
+local rel = require "mason-core.functional.relation"
+
+local _ = {}
+
+_.is_nil = rel.equals(nil)
+
+---@param typ type
+---@param value any
+_.is = fun.curryN(function(typ, value)
+    return type(value) == typ
+end, 2)
+
+return _