nel/helper.lua

local old_print = print
function print(...)
  local info = debug.getinfo(2)
  local line = info.currentline
  local name = info.source
  old_print(string.format("%i%s> ",line,name),...)
end
function log(...)
  old_print(...)
end
function map(tab,func)
  local new = {}
  for index,item in pairs(tab) do
    new[index] = func(item)
  end
  return new
end
-- HELPER FUNCTIONS
-- Insert every item in t1 into t0
function just(...)
  local items = {...}
  return function()
    return table.unpack(items)
  end
end

id = function(...) return ... end

function union(t0,t1)
  for index,item in pairs(t0) do
    t0[index] = t1
  end
  return t0
end

-- Iterate (ipairs without the index)
function iterate(...)
  local iterator,tab,i = pairs(...)
  return function(...)
    local index,item = iterator(tab,i)
    i = index
    return item
  end,tab,i
end

function indices(t)
  if type(t) ~= "table" then
    error(
      string.format(
        "Argument 1 '%s' must be a table",
        tostring(t)
      )
    ,2)
  end
  local indices = {}
  for index,_ in pairs(t) do
    table.insert(indices,index)
  end
  return indices
end

-- Ensures a table has a metatable
function ensure_metatable(t)
  local meta = getmetatable(t)
  if not meta then meta = {} setmetatable(t,meta) end
  return meta
end

function strings(t,item)
  ensure_metatable(t).__tostring = item
end

-- Makes a table callable
function calls(t,fun)
  ensure_metatable(t).__call = fun
end

-- Makes a table record access
function indexes(t,fun)
  ensure_metatable(t).__index = fun
end

-- Makes a table record setting
function modifies(t,fun)
  ensure_metatable(t).__newindex = fun
end

-- Shallow table to string
function table_tostring(tab,sep)
   local items = {}
   for item in iterate(tab) do
     table.insert(items,tostring(item))
   end
   return table.concat(items,sep)
end

function type_of(item)
  local type_name = type(item)
  if type_name == "table" then
    local meta = getmetatable(item)
    if not meta then 
      return "table" 
    else
      return meta
    end
  else
    return type_name
  end
end

-- DEBUGGING FUNCTIONS
-- Runs a function 
function assert_meta(...)
  local metas = {...}
  return function(x,raise,handler)
    handler = handler or error
    local meta = getmetatable(x)
    for tab in iterate(metas) do
      if meta == tab then return end
    end
    local s_metas = {}
    for meta in iterate(metas) do
      table.insert(s_metas,tostring(meta))
    end
    local level = 2
    local msg = string.format(
        "Expected metatables '%s' but got '%s'",
        table.concat(s_metas,","),
        type(x)
      )
    if raise then
      level = 3
      msg = string.format(raise,msg)
    end
    handler(msg,level)
  end
end

function assert_type(...)
  local types = {...}
  return function(x,raise)
    local t = type(x)
    for name in iterate(types) do
      if t == name then return end
    end
    local level = 2
    local msg = string.format(
        "Expected type '%s' but got '%s'",
        table_tostring(types," or "),
        type(x))
    -- For argument errors
    if raise then 
      level = 3 
      msg = string.format(raise,msg)
    end
    error(msg,level)
  end
end

-- HELPER FUNCTIONS
function case_of(t)
  return function(item,...)
    return (t[item] or error(
      string.format(
        "Couldn't match '%s' in case.",
        tostring(item)
      ),2
    ))(...)
  end
end

-- Creates a (p)OOP class
function class(name)
  local meta = {}
  union(meta,{restrict = {}})
  meta.__index = meta
  strings(meta,just(name))
  calls(meta,function(meta,...)
    local new = {}
    setmetatable(new,meta)
    if meta.new then new:new(...) end
    return new
  end)
  meta.__tostring = function(this)
    if meta.string then return this:string() end
    return name
  end
  return meta
end

-- Read a file's full contents
function read(path)
  local file = io.open(path)
  if not file then
    error(
      string.match("Could not open file '%s'.",path),3
    )
  end
  local content = file:read("a")
  return content
end

return _G