Typical - fancy type names for Lua

The Lua builtin function type has a disadvantage: it only returns the 'primitive' Lua type of a value. So if you want to implement your own typing system with custom type names, type won't provide you any interesting information:

local object = setmetatable({}, { __type = 'object' })
print(type(object)) -- prints 'table'

Some libraries (such as the I/O library included with standard Lua) offer alternative type functions for identifying types used within that library:

print(io.type(value) or type(value))

Typical is a library that offers an enhanced version of type that is meant to be more generic:

local type = require 'typical'
local object = setmetatable({}, { __type = 'object' })
print(type(object)) -- prints 'object'

Typical is very simple: it looks for a __type metafield on an object. If it's a function, it passes the value to the function and uses the result as the type name. If it's a string, it uses that. If __type is nil or returns nil, the builtin type is used.

Library Overview

If you want to use typical just like a function, you can:

local type = require 'typical'

However, the type object is just an alias for typical.type:

local typical = require 'typical'
print(typical.type(value)) -- same as typical(value)

Typical also provides other type-related methods for your convenience; you can read about them in the 'Methods' section.

Methods

typical.type(value)

Returns the type name for a value.