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Global & Base

This page documents the changes & additions to Pluto's runtime environment, which is built on top of Lua 5.4's.

_PVERSION​

_PVERSION is the global to check your current version of Pluto.

pluto
if _PVERSION == nil then
    print("Plain Lua detected (".._VERSION..")")
else
    io.write("Pluto detected (".._PVERSION.."), based on ".._VERSION)
    if os.platform then
        io.write(", running on "..os.platform)
    end
    io.write("\n")
end

package.path​

package.path is modified to also search for .pluto files.

Default Metatables​

Tables and coroutines/threads have metatables by default, akin to how each string has a metatable by default.

pluto
local t = {}
local c = coroutine.create(|| -> do end)
-- Can do this:
t:contains(1)
t:concat("\n")
c:resume()
-- As opposed to this:
table.contains(t, 1)
table.concat(t, "\n")
coroutine.resume(c)

The default metatables for the types are as follows:

  • Table: { __mindex = _G.table } (using Pluto's own __mindex metamethod)
  • Coroutine/thread: { __index = _G.coroutine }

dumpvar​

A debug function designed to dump values into human-readable formats.

Parameters​

  1. The value to dump.

Returns​

A string representation of the value.

pluto
local t = {
    ["hello"] = 1234,
    ["goodbye"] = _G.table,
    ["name"] = "John",
    ["lastname"] = "Doe",
    ["details"] = {
        "No details available."
    }
}
print(dumpvar(t))
{
    ["lastname"] = string(3) "Doe",
    ["name"] = string(4) "John",
    ["goodbye"] = {
        ["unpack"] = function: 00007FF7738B3C20,
        ["insert"] = function: 00007FF7738B30D0,
        ["freeze"] = function: 00007FF7738B43F0,
        ["foreach"] = function: 00007FF7738B3220,
        ["filter"] = function: 00007FF7738B4700,
        ["isfrozen"] = function: 00007FF7738B44B0,
        ["getn"] = function: 00007FF7738B43B0,
        ["pack"] = function: 00007FF7738B3B10,
        ["contains"] = function: 00007FF7738B4540,
        ["move"] = function: 00007FF7738B34D0,
        ["concat"] = function: 00007FF7738B37F0,
        ["sort"] = function: 00007FF7738B42B0,
        ["remove"] = function: 00007FF7738B33C0,
        ["map"] = function: 00007FF7738B49A0,
    },
    ["hello"] = 1234,
    ["details"] = {
        [1] = string(21) "No details available.",
    },
}

exportvar​

Similar to dumpvar, but returns valid Lua/Pluto code. May error if the value can not be represented accordingly.

Parameters​

  1. The value to dump.
pluto
-- Slightly altered data from last example as C functions can not be exported.
local t = {
    ["hello"] = 1234,
    ["name"] = "John",
    ["lastname"] = "Doe",
    ["details"] = {
        "No details available."
    }
}
print(exportvar(t))
{
    ["hello"] = 1234,
    ["name"] = "John",
    ["details"] = {
        [1] = "No details available.",
    },
    ["lastname"] = "Doe",
}

range​

Returns a table of numbers in the given range.

pluto
print(range(10):unpack())   --> 1   2   3   4   5   6   7   8   9   10
print(range(4, 8):unpack()) --> 4   5   6   7   8

compareversions​

Performs a three-way comparison on 2 version numbers, similar to the Spaceship Operator.

pluto
assert(compareversions("1.0.0", "0.9.0")     >= 0)
assert(compareversions("1.0.0", "1.0.0-dev") >= 0)

Note that pre-release versions (e.g. with -dev suffix) are considered to be less than their final counterparts.

wcall​

Calls the given function and returns a string of warnings raised by it.

pluto
local w = wcall(|| -> warn("Bad!"))
print(w ~= "" ? (w:strip()) : "No warnings")
-- Output: "Bad!"

sdiv, udiv​

Performs a standard integer division (signed and unsigned).

pluto
assert(0xefffffffffffffff // 12 == -96076792050570582)
assert(sdiv(0xefffffffffffffff, 12) == -96076792050570581)
assert(udiv(0xefffffffffffffff, 12) == 1441151880758558719)

smod, umod​

Performs a standard integer modulo operation (signed and unsigned).

pluto
assert(0xefffffffffffffff % 12 == 7)
assert(smod(0xefffffffffffffff, 12) == -5)
assert(umod(0xefffffffffffffff, 12) == 11)

callonce​

Calls the given function exactly once and then caches its return value.

pluto
local function expensive_constructor()
    print("expensive_constructor called")
    return { "A", "B", "C" }
end
for i = 1, 3 do
    local t = callonce(expensive_constructor)
    print(t[i])
end
--> expensive_constructor called
--> A
--> B
--> C