pod: plain-old-data library and serialization

A Lua library for specifying and converting types to/from "plain old data" and methods to serialize/deserialize those types to/from bytes. In Lua, the 5 supported types considered "plain old data" are: nil, boolean, integer, string and any table of only these types.

local M = mod'mymod'

local mty = require'metaty'

local pod = require'pod'

-- enums are already plain-old-data.

M.Job = mty.enum'Job' { BOSS = 1, PEON = 2 }

--- records need to have pod() called on them.

--- This implements __toPod and __fromPod for the metaty record.

M.Worker = pod(mty'Worker' {

  'name [string] #1',    -- must specify type and #id

  'job  [mymod.Job] #2', -- can lookup any type in PKG_LOOKUP

  'salary [int] #3',

  'schedule {int: mymod.Schedule} #4', -- map of weekday[1,7] -> scheduled time

})

M.Schedule = pod(mty'Schedule' {

  'start [int]: start time in seconds since midnight',

  'stop  [int]: stop time in seconds since midnight',

})

local serialized = pod.ser(M.Worker{...})   -- convert to string

local worker = pod.de(serialized, M.Worker) -- convert from string

Explanation of above:

metaty.enum are already plain-old-data (no need to call pod() on them).
metaty record types can be made plain old data by calling the pod() module on them.
This simply implements the __toPod and __fromPod methods on them -- you can do this yourself if you prefer!
pod parses the metaty field type stanza as [singleType

, {listType} or {map: type} repsecitively. The collection types are converted to pod.List and pod.Map respectively.