fix the rest / remove argument of inst

Author: Nymphium

example/example.lua

@@ -1,7 +1,7 @@
 local eff = require('eff')
 local inst, perform, handler = eff.inst, eff.perform, eff.handler
 
-local Write = inst("Write")
+local Write = inst()
 
 local test = function()
   local x = perform(Write("hello"))
@@ -24,15 +24,15 @@ function(k, arg)
   k()
 end)
 
-local Choice = inst("Choice")
+local Choice = inst()
 
 local choiceh = handler(Choice,
 function(v) return v end,
 function(k, l, _)
   k(l)
 end)
 
-local Any = inst("Any")
+local Any = inst()
 
 local anyh = handler(Any,
   function(v) print("anyh ended", v) return v end,

example/monadic_pcall.lua

@@ -1,7 +1,7 @@
 local eff = require('eff')
 local inst, perform, handler = eff.inst, eff.perform, eff.handler
 
-local Pcall = inst("Pcall")
+local Pcall = inst()
 local epcall = function(f, ...)
   return perform(Pcall(f, ...))
 end

example/nilcheck.lua

@@ -1,10 +1,10 @@
 local eff = require('eff')
 local inst, perform, handler = eff.inst, eff.perform, eff.handler
 
-local Fetch = inst("Fetch")
+local Fetch = inst()
 local fetch = function(it) return perform(Fetch(it)) end
 
-local Fallback = inst("Fallback")
+local Fallback = inst()
 
 local fetchh = handler(Fetch,
   function(v) return v end,

example/shiftreset.lua

@@ -6,7 +6,7 @@ local inspect = require("inspect")
 local sr
 do
   local new_prompt = function()
-    local Shift0 = inst("Shift0")
+    local Shift0 = inst()
 
     return {
       take = function(f) return perform(Shift0(f)) end,
@@ -84,7 +84,7 @@ print([[
 
 local promless
 do
-  local Shift0 = inst("Shift0")
+  local Shift0 = inst()
 
   local shift0 = function(f)
     return perform(Shift0(f))

example/typeclass.lua

@@ -6,8 +6,8 @@ monoid
 =====]])
 
 do
-  local Empty = inst("Empty")
-  local Concat = inst("Concat")
+  local Empty = inst()
+  local Concat = inst()
 
   local empty = function()
     return perform(Empty())
@@ -81,7 +81,7 @@ fmap
 ===]])
 
 do
-  local Map = inst("Map")
+  local Map = inst()
 
   local map = function(f, fa)
     return perform(Map(f, fa))

src/eff.lua

@@ -18,9 +18,9 @@ do
   local v = {}
   v.cls = ("Eff: %s"):format(tostring(v):match('0x[0-f]+'))
 
-  inst = setmetatable(v, {__call = function(self, eff)
+  inst = setmetatable(v, {__call = function(self)
     -- uniqnize
-    eff = ("%s: %s"):format(eff, tostring{}:match('0x[0-f]+'))
+    local eff = ("instance: %s"):format(tostring{}:match('0x[0-f]+'))
     local _Eff = setmetatable({eff = eff}, {__index = self})
 
     return setmetatable({--[[arg = nil]]}, {