String-lambdas with syntax inspired by OCaml/F#

fun.lua

-- taken from http://lua-users.org/wiki/StringTrim
function trim(s)
  return s:match "^%s*(.-)%s*$"
end

-- creates a function from a lambda string
function fun(text)
  -- divide the text into arg list and return body
  local a, r = text:match("(.-)->(.*)")

  a = trim(a)
  r = trim(r)

  -- we use a local, named function so that lambdas can recursively call themselves
  local src = string.format([[-- %s
local function fun(%s) return (%s) end
return fun
]],
    text, a:gsub('%s+', ','), r)

  return assert(loadstring(src))()
end

-- recursive factorial lambda
factorial = fun[[a s -> a > 0 and fun(a - 1, (s or 1) * a) or (s or 1)]]

-- maps a function over an array table
function map(f, t)
  local r = {}
  for i = 1, #t do
    r[i] = f(t[i])
  end
  return r
end

-- problem: lambdas can currently only access data declared in the global scope
local results = map(fun[[a -> factorial(a)]], {1, 2, 3, 4, 5, 6, 7, 8, 9, 10})
print(unpack(results))