Pipes in lua with metamethods

brackpipe.lua

local function pipe(val)
  return setmetatable({ val = val }, {
    __index = function(_, fn)
      return pipe(fn(val))
    end,
    __unm = function(x)
      return x.val
    end
  })
end

print(
  - pipe(1)
  [ function(x) return x + 1 end ]
  [ function(x) return x + 2 end ]
) -- 4

pluspipe.lua

-- Pipes in lua

local function pipe(val)
  return setmetatable({ val = val }, {
    __add = function(x, fn)
      return pipe(fn(x.val))
    end,
    __unm = function(x)
      return x.val
    end
  })
end

-- Use as wrapped value
local v =
  pipe(1)
  + function(x) return x + 1 end
  + function(x) return x + 2 end

print(-v) -- 4

-- or paren with unwrap
print(
  - (pipe('a')
  + function (x) return x .. 'b' end
  + function (x) return x .. 'c' end
  )
) -- abc

-- no lsp support