-- This file:
--   http://anggtwu.net/LUA/Fold1.lua.html
--   http://anggtwu.net/LUA/Fold1.lua
--          (find-angg "LUA/Fold1.lua")
-- Author: Eduardo Ochs <eduardoochs@gmail.com>
-- Based on:
--   (find-angg "LUA/ELpeg1.lua" "folds")
--
-- (defun e () (interactive) (find-angg "LUA/Fold1.lua"))
-- (find-angg "LUA/ELpeg1.lua" "folds")
-- (find-angg "LUA/lua50init.lua" "fold")

Fold = Class {
  type    = "Fold",
  __index = {
    l = function (fold, f)
        local A,o = fold.A, fold.A[1]
        for i=2,#A do local b=A[i]; o=f(o,b) end
        return o
      end,
    r = function (fold, f)
        local A,o = fold.A, fold.A[#fold.A]
        for i=#A-1,1,-1 do local a=A[i]; o=f(a,o) end
        return o
      end,
    l2 = function (fold, f)
        local A,o = fold.A, fold.A[1]
        for i=3,#A,2 do local b,c=A[i-1],A[i]; o=f(o,b,c) end
        return o
      end,
    r2 = function (fold, f)
        local A,o = fold.A, fold.A[#fold.A]
        for i=#A-2,1,-2 do local a,b=A[i],A[i+1]; o=f(a,b,o) end
        return o
      end,
  },
}



--[[
* (eepitch-lua51)
* (eepitch-kill)
* (eepitch-lua51)
dofile "Fold1.lua"
A = {10, 20, 30, 40, 50, 60, 70}
F = Fold {A=A}
f2 = function(a,b) return format("(%s.%s)", a,b) end
f3 = function(a,b,c) return format("(%s.%s.%s)", a,b,c) end
= F:l(f2)
= F:r(f2)
= F:l2(f3)
= F:r2(f3)


--]]






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-- coding:  utf-8-unix
-- End: