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--- lam.list
local list = {}
local util = require "util"
local types = require "types"
table.unpack = table.unpack or unpack
list.Null = setmetatable({}, {
__type = "Null",
__tostring = function(self) return "()" end,
})
list.isNull =
function (x)
return x == list.Null
end
list.List =
function (tbl)
local function tolist (base, items)
if #items == 0 then return base end
return tolist (
types.Cons(table.remove(items), base),
items
)
end
return tolist(list.Null, tbl)
end
list.isList =
function (x)
if list.isNull(x) then
return true
elseif types.isa(x, "Pair") then
return list.isList(x[2])
else
return false
end
end
list.fold1 =
function (fn, seed, lis)
if list.isNull(lis) then return seed end
return list.fold1(fn, fn(seed, lis[1]), lis[2])
end
---
return list
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