Version 1.4.1

Stripped all trailing whitespace, changed ease function, and pre-computed po2

README.md

@@ -38,7 +38,7 @@ lume.lerp(100, 200, .5) -- Returns 150
 ```
 
 ### lume.smooth(a, b, amount)
-Similar to `lume.lerp()` but uses cosine interpolation instead of linear
+Similar to `lume.lerp()` but uses cubic interpolation instead of linear
 interpolation.
 
 ### lume.pingpong(x)
@@ -64,6 +64,16 @@ raised.
 lume.randomchoice({true, false}) -- Returns either true or false
 ```
 
+### lume.weightedchoice(t)
+Takes the argument table `t` where the keys are the possible choices and the
+value is the choice's weight. A weight should be 0 or above, the larger the
+number the higher the probability of that choice being picked. If the table is
+empty, a weight is below zero or all the weights are 0 then an error is raised.
+```lua
+lume.weightedchoice({ ["cat"] = 10, ["dog"] = 5, ["frog"] = 0 })
+-- Returns either "cat" or "dog" with "cat" being twice as likely to be chosen.
+```
+
 ### lume.shuffle(t)
 Shuffles the values of array `t` in place, returns the array.
 
@@ -105,12 +115,14 @@ supplied it is called on each value, true is returned if any of the calls to
 lume.any({1, 2, 1}, function(x) return x == 1 end) -- Returns true
 ```
 
-### lume.reduce(t, fn, first)
+### lume.reduce(t, fn [, first])
 Applies `fn` on two arguments cumulative to the items of the array `t`, from
-left to right, so as to reduce the array to a single value. The accumulator is
-intialised to the `first` value.
+left to right, so as to reduce the array to a single value. If a `first` value
+is specified the accumulator is initialised to this, otherwise the first value
+in the array is used. If the array is empty and no `first` value is specified
+an error is raised,
 ```lua
-lume.reduce({1, 2, 3}, function(a, b) return a + b end, 0) -- Returns 6
+lume.reduce({1, 2, 3}, function(a, b) return a + b end) -- Returns 6
 ```
 
 ### lume.set(t [, retainkeys])
@@ -118,7 +130,7 @@ Returns a copy of the `t` table with all the duplicate values removed. If
 `retainkeys` is true the table is not treated as an array and retains its
 original keys.
 ```lua
-lume.set({2, 1, 2, "cat", "cat"}) -- Returns {1, 2, cat}
+lume.set({2, 1, 2, "cat", "cat"}) -- Returns {1, 2, "cat"}
 ```
 
 ### lume.filter(t, fn [, retainkeys])
@@ -144,6 +156,21 @@ exist in the table.
 lume.find({"a", "b", "c"}, "b") -- Returns 2
 ```
 
+### lume.match(t, fn)
+Returns the value and key of the value in table `t` which returns true when
+`fn` is called on it. Returns `nil` if no such value exists.
+```lua
+lume.match({1, 5, 8, 7}, function(x) return x % 2 == 0 end) -- Returns 8, 3
+```
+
+### lume.count(t [, fn])
+Counts the number of values in the table `t`. If a `fn` function is supplied it
+is called on each value, the number of times it returns true is counted.
+```lua
+lume.count({a = 2, b = 3, c = 4, d = 5}) -- Returns 4
+lume.count({1, 2, 4, 6}, function(x) return x % 2 == 0 end) -- Returns 3
+```
+
 ### lume.slice(t [, i [, j]])
 Mimics the behaviour of Lua's `string.sub`, but operates on an array rather
 than a string. Creates and returns a new array of the given slice.
@@ -151,6 +178,13 @@ than a string. Creates and returns a new array of the given slice.
 lume.slice({"a", "b", "c", "d", "e"}, 2, 4) -- Returns {"b", "c", "d"}
 ```
 
+### lume.invert(t)
+Returns a copy of the table where the keys have become the values and the
+values the keys.
+```lua
+lume.invert({a = "x", b = "y"}) -- returns {x = "a", y = "b"}
+```
+
 ### lume.clone(t)
 Returns a shallow copy of the table `t`.
 
@@ -174,6 +208,25 @@ f() -- Prints "Hello"
 f() -- Does nothing
 ```
 
+### lume.memoize(fn)
+Returns a wrapper function to `fn` where the results for any given set of
+arguments are cached. `lume.memoize()` is useful when used on functions with
+slow-running computations.
+```lua
+fib = lume.memoize(function(n) return n < 2 and n or fib(n-1) + fib(n-2) end)
+```
+
+### lume.combine(...)
+Creates a wrapper function which calls each supplied argument in the order they
+were passed to `lume.combine()`; nil arguments are ignored. The wrapper
+function passes its own arguments to each of its wrapped functions when it is
+called.
+```lua
+local f = lume.combine(function(a, b) print(a + b) end,
+                       function(a, b) print(a * b) end)
+f(3, 4) -- Prints "7" then "12" on a new line
+```
+
 ### lume.time(fn, ...)
 Inserts the arguments into function `fn` and calls it. Returns the time in
 seconds the function `fn` took to execute followed by `fn`'s returned values.
@@ -181,6 +234,15 @@ seconds the function `fn` took to execute followed by `fn`'s returned values.
 lume.time(function(x) return x end, "hello") -- Returns 0, "hello"
 ```
 
+### lume.lambda(str)
+Takes a string lambda and returns a function. `str` should be a list of
+comma-separated parameters, followed by `->`, followed by the expression which
+will be evaluated and returned.
+```lua
+local f = lume.lambda "x,y -> 2*x+y"
+f(10, 5) -- Returns 25
+```
+
 ### lume.serialize(x)
 Serializes the argument `x` into a string which can be loaded again using
 `lume.deserialize()`. Only booleans, numbers, tables and strings can be
@@ -199,11 +261,12 @@ lume.deserialize("{1, 2, 3}") -- Returns {1, 2, 3}
 ```
 
 ### lume.split(str [, sep])
-Splits the string `str` into words and returns a table of the sub strings. If
-`sep` is provided the string will be split at any of the characters in `sep`
-instead of on whitespace.
+Returns an array of the words in the string `str`. If `sep` is provided it is
+used as the delimiter, consecutive delimiters are not grouped together and will
+delimit empty strings.
 ```lua
 lume.split("One two three") -- Returns {"One", "two", "three"}
+lume.split("a,b,,c", ",") -- Returns {"a", "b", "", "c"}
 ```
 
 ### lume.trim(str [, chars])
@@ -237,6 +300,10 @@ Executes the lua code inside `str`.
 lume.dostring("print('Hello!')") -- Prints "Hello!"
 ```
 
+### lume.uuid()
+Generates a random UUID string; version 4 as specified in
+[RFC 4122](http://www.ietf.org/rfc/rfc4122.txt).
+
 ### lume.hotswap(modname)
 Reloads an already loaded module in place, allowing you to immediately see the
 effects of code changes without having to restart the program. `modname` should
@@ -256,6 +323,17 @@ arguments to [LÖVE](http://love2d.org)'s setColor() function.
 lume.rgba(0xFF304050) -- Returns 48, 64, 80, 255
 ```
 
+### lume.chain(value)
+Returns a wrapped object which allows chaining of lume functions. The function
+result() should be called at the end of the chain to return the resulting
+value.
+```lua
+lume.chain({1, 2, 3, 4})
+  :filter(function(x) return x % 2 == 0 end)
+  :map(function(x) return -x end)
+  :result() -- Returns { -2, -4 }
+```
+
 
 ## License
 

lume.lua

@@ -7,17 +7,44 @@
 -- under the terms of the MIT license. See LICENSE for details.
 --
 
-local lume = { _version = "1.1.0" }
+local lume = { _version = "1.4.1" }
+
+local pairs, ipairs = pairs, ipairs
+local type, assert, unpack = type, assert, unpack or table.unpack
+local tostring, tonumber = tostring, tonumber
+local math_floor = math.floor
+local math_ceil = math.ceil
+local math_random = math.random
+local math_cos = math.cos
+local math_atan2 = math.atan2
+local math_sqrt = math.sqrt
+local math_abs = math.abs
+local math_pi = math.pi
+
+local patternescape = function(str)
+  return str:gsub("[%(%)%.%%%+%-%*%?%[%]%^%$]", "%%%1")
+end
+
+local absindex = function(len, i)
+  return i < 0 and (len + i + 1) or i
+end
+
+local iscallable = function(x)
+  if type(x) == "function" then return true end
+  local mt = getmetatable(x)
+  return mt and mt.__call ~= nil
+end
+
 
 
 function lume.clamp(x, min, max)
-  return math.max(math.min(x, max), min)
+  return x < min and min or (x > max and max or x)
 end
 
 
 function lume.round(x, increment)
   if increment then return lume.round(x / increment) * increment end
-  return x > 0 and math.floor(x + .5) or math.ceil(x - .5)
+  return x > 0 and math_floor(x + .5) or math_ceil(x - .5)
 end
 
 
@@ -32,42 +59,60 @@ end
 
 
 function lume.smooth(a, b, amount)
-  local m = (1 - math.cos(lume.clamp(amount, 0, 1) * math.pi)) / 2
+  local t = lume.clamp(amount, 0, 1)
+  local m = t * t * (3 - 2 * t)
   return a + (b - a) * m
 end
 
 
 function lume.pingpong(x)
-  return 1 - math.abs(1 - x % 2)
+  return 1 - math_abs(1 - x % 2)
 end
 
 
 function lume.distance(x1, y1, x2, y2, squared)
-  local s = (x1 - x2) ^ 2 + (y1 - y2) ^ 2
-  return squared and s or math.sqrt(s)
+  local dx = x1 - x2
+  local dy = y1 - y2
+  local s = dx * dx + dy * dy
+  return squared and s or math_sqrt(s)
 end
 
 
 function lume.angle(x1, y1, x2, y2)
-  return math.atan2(y2 - y1, x2 - x1)
+  return math_atan2(y2 - y1, x2 - x1)
 end
 
 
 function lume.random(a, b)
   if not a then a, b = 0, 1 end
   if not b then b = 0 end
-  return a + math.random() * (b - a)
+  return a + math_random() * (b - a)
 end
 
 
 function lume.randomchoice(t)
-  return t[math.random(#t)]
+  return t[math_random(#t)]
+end
+
+
+function lume.weightedchoice(t)
+  local sum = 0
+  for k, v in pairs(t) do
+    assert(v >= 0, "weight value less than zero")
+    sum = sum + v
+  end
+  assert(sum ~= 0, "all weights are zero")
+  local rnd = lume.random(sum)
+  for k, v in pairs(t) do
+    if rnd < v then return k end
+    rnd = rnd - v
+  end
 end
 
 
 function lume.shuffle(t)
   for i = 1, #t do
-    local r = math.random(#t)
+    local r = math_random(#t)
     t[i], t[r] = t[r], t[i]
   end
   return t
@@ -76,7 +121,7 @@ end
 
 function lume.array(...)
   local t = {}
-  for x in unpack({...}) do t[#t + 1] = x end
+  for x in ... do t[#t + 1] = x end
   return t
 end
 
@@ -92,7 +137,7 @@ end
 
 
 function lume.map(t, fn)
-  local rtn = {} 
+  local rtn = {}
   for k, v in pairs(t) do rtn[k] = fn(v) end
   return rtn
 end
@@ -117,16 +162,18 @@ end
 
 
 function lume.reduce(t, fn, first)
-  for i = 1, #t do first = fn(first, t[i]) end
-  return first
+  local acc = first or t[1]
+  assert(acc, "reduce of an empty array with no first value")
+  for i = first and 1 or 2, #t do acc = fn(acc, t[i]) end
+  return acc
 end
 
 
 function lume.set(t, retainkeys)
-  local tmp = {}
-  for k, v in pairs(t) do tmp[v] = k end
   local rtn = {}
-  for k, v in pairs(tmp) do rtn[retainkeys and v or (#rtn + 1)] = k end
+  for k, v in pairs(lume.invert(t)) do
+    rtn[retainkeys and v or (#rtn + 1)] = k
+  end
   return rtn
 end
 
@@ -156,13 +203,41 @@ function lume.find(t, value)
 end
 
 
-function lume.slice(t, i, j)
-  i = i or 1
-  j = j and (j < 0 and (#t + j + 1) or j) or #t
-  local rtn = {}
-  for i = math.max(i, 1), math.min(j, #t) do
-    rtn[#rtn + 1] = t[i]
+function lume.match(t, fn)
+  for k, v in pairs(t) do
+    if fn(v) then return v, k end
   end
+  return nil
+end
+
+
+function lume.count(t, fn)
+  local count = 0
+  if fn then
+    for k, v in pairs(t) do
+      if fn(v) then count = count + 1 end
+    end
+  else
+    for k in pairs(t) do count = count + 1 end
+  end
+  return count
+end
+
+
+function lume.slice(t, i, j)
+  i = i and absindex(#t, i) or 1
+  j = j and absindex(#t, j) or #t
+  local rtn = {}
+  for x = i < 1 and 1 or i, j > #t and #t or j do
+    rtn[#rtn + 1] = t[x]
+  end
+  return rtn
+end
+
+
+function lume.invert(t)
+  local rtn = {}
+  for k, v in pairs(t) do rtn[v] = k end
   return rtn
 end
 
@@ -175,10 +250,11 @@ end
 
 
 function lume.fn(fn, ...)
+  assert(iscallable(fn), "expected a function as the first argument")
   local args = {...}
   return function(...)
     local a = lume.merge(lume.clone(args), {...})
-    return fn(unpack(a)) 
+    return fn(unpack(a))
   end
 end
 
@@ -194,6 +270,39 @@ function lume.once(fn, ...)
 end
 
 
+local memoize_fnkey = {}
+local memoize_nil = {}
+
+function lume.memoize(fn)
+  local cache = {}
+  return function(...)
+    local c = cache
+    for i = 1, select("#", ...) do
+      local a = select(i, ...) or memoize_nil
+      c[a] = c[a] or {}
+      c = c[a]
+    end
+    c[memoize_fnkey] = c[memoize_fnkey] or {fn(...)}
+    return unpack(c[memoize_fnkey])
+  end
+end
+
+
+function lume.combine(...)
+  local funcs = {}
+  for i = 1, select("#", ...) do
+    local fn = select(i, ...)
+    if fn ~= nil then
+      assert(iscallable(fn), "expected a function or nil")
+      funcs[#funcs + 1] = fn
+    end
+  end
+  return function(...)
+    for _, f in ipairs(funcs) do f(...) end
+  end
+end
+
+
 function lume.time(fn, ...)
   local start = os.clock()
   local rtn = {fn(...)}
@@ -201,6 +310,19 @@ function lume.time(fn, ...)
 end
 
 
+local lambda_cache = {}
+
+function lume.lambda(str)
+  if not lambda_cache[str] then
+    local args, body = str:match([[^([%w,_ ]-)%->(.-)$]])
+    assert(args and body, "bad string lambda")
+    local s = "return function(" .. args .. ")\nreturn " .. body .. "\nend"
+    lambda_cache[str] = lume.dostring(s)
+  end
+  return lambda_cache[str]
+end
+
+
 function lume.serialize(x)
   local f = { string = function(v) return string.format("%q", v) end,
               number = tostring, boolean = tostring }
@@ -211,6 +333,8 @@ function lume.serialize(x)
     end
     return "{" .. table.concat(rtn) .. "}"
   end
+  local err = function(t,k) error("unsupported serialize type: " .. k) end
+  setmetatable(f, { __index = err })
   return f[type(x)](x)
 end
 
@@ -221,20 +345,27 @@ end
 
 
 function lume.split(str, sep)
-  return lume.array(str:gmatch("([^" .. (sep or "%s") .. "]+)"))
+  if not sep then
+    return lume.array(str:gmatch("([%S]+)"))
+  else
+    assert(sep ~= "", "empty separator")
+    local psep = patternescape(sep)
+    return lume.array((str..sep):gmatch("(.-)("..psep..")"))
+  end
 end
 
 
 function lume.trim(str, chars)
-  chars = chars or "%s"
+  if not chars then return str:match("^[%s]*(.-)[%s]*$") end
+  chars = patternescape(chars)
   return str:match("^[" .. chars .. "]*(.-)[" .. chars .. "]*$")
 end
 
 
 function lume.format(str, vars)
   if not vars then return str end
-  local f = function(x) 
-    return tostring(vars[x] or vars[tonumber(x)] or "{" .. x .. "}") 
+  local f = function(x)
+    return tostring(vars[x] or vars[tonumber(x)] or "{" .. x .. "}")
   end
   return (str:gsub("{(.-)}", f))
 end
@@ -242,8 +373,13 @@ end
 
 function lume.trace(...)
   local info = debug.getinfo(2, "Sl")
-  local head = "[" .. info.short_src .. ":" .. info.currentline .. "] "
-  print(head .. table.concat(lume.map({...}, tostring), " "))
+  local t = { "[" .. info.short_src .. ":" .. info.currentline .. "]" }
+  for i = 1, select("#", ...) do
+    local x = select(i, ...)
+    x = (type(x) == "number") and lume.round(x, .01) or (x or "nil")
+    t[#t + 1] = tostring(x)
+  end
+  print(table.concat(t, " "))
 end
 
 
@@ -252,11 +388,21 @@ function lume.dostring(str)
 end
 
 
+function lume.uuid()
+  local fn = function(x)
+    local r = math_random(16) - 1
+    r = (x == "x") and (r + 1) or (r % 4) + 9
+    return ("0123456789abcdef"):sub(r, r)
+  end
+  return (("xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx"):gsub("[xy]", fn))
+end
+
+
 function lume.hotswap(modname)
   local oldglobal = lume.clone(_G)
   local updated = {}
   local function update(old, new)
-    if updated[old] then return end 
+    if updated[old] then return end
     updated[old] = true
     local oldmt, newmt = getmetatable(old), getmetatable(new)
     if oldmt and newmt then update(oldmt, newmt) end
@@ -264,18 +410,19 @@ function lume.hotswap(modname)
       if type(v) == "table" then update(old[k], v) else old[k] = v end
     end
   end
-  local oldmod = pcall(require, modname) or nil
   local err = nil
   local function onerror(e)
     for k, v in pairs(_G) do _G[k] = oldglobal[k] end
     err = lume.trim(e)
   end
+  local ok, oldmod = pcall(require, modname)
+  oldmod = ok and oldmod or nil
   xpcall(function()
     package.loaded[modname] = nil
     local newmod = require(modname)
     if type(oldmod) == "table" then update(oldmod, newmod) end
     for k, v in pairs(oldglobal) do
-      if v ~= _G[k] and type(v) == "table" then 
+      if v ~= _G[k] and type(v) == "table" then
         update(v, _G[k])
         _G[k] = v
       end
@@ -288,13 +435,27 @@ end
 
 
 function lume.rgba(color)
-  local floor = math.floor
-  local a = floor((color / 2 ^ 24) % 256)
-  local r = floor((color / 2 ^ 16) % 256)
-  local g = floor((color / 2 ^ 08) % 256)
-  local b = floor((color) % 256)
+  local a = math_floor((color / 16777216) % 256)
+  local r = math_floor((color /    65536) % 256)
+  local g = math_floor((color /      256) % 256)
+  local b = math_floor((color) % 256)
   return r, g, b, a
 end
 
 
+local chain_mt = {}
+chain_mt.__index = lume.map(lume.filter(lume, iscallable, true),
+  function(fn)
+    return function(self, ...)
+      self._value = fn(self._value, ...)
+      return self
+    end
+  end)
+chain_mt.__index.result = function(x) return x._value end
+
+function lume.chain(value)
+  return setmetatable({ _value = value }, chain_mt)
+end
+
+
 return lume

test/test_lume.lua

@@ -64,11 +64,11 @@ end
 
 -- lume.distance
 tests["lume.distance"] = function()
-  testeq( lume.distance(10, 20, 10, 20), 0  )
-  testeq( lume.distance(10, 20, 20, 20), 10 )
-  local x = lume.distance(1, 2, 5, 7)
-  testeq( lume.distance(1, 2, 5, 7, true),      x * x   )
-  testeq( lume.distance(10, 10, 10, 20, true),  10 * 10 )
+  testeq( lume.distance(15, 20, 15, 20),        0             )
+  testeq( lume.distance(13, 44, 156, 232),      236.205419074 )
+  testeq( lume.distance(-23, 66, -232, 123),    216.633330769 )
+  local x = lume.distance(13, 15, -2, 81)
+  testeq( lume.distance(13, 15, -2, 81, true),  x * x         )
 end
 
 -- lume.angle
@@ -82,6 +82,9 @@ end
 
 -- lume.random
 tests["lume.random"] = function()
+  testeq( type(lume.random()),      "number" )
+  testeq( type(lume.random(1)),     "number" )
+  testeq( type(lume.random(1, 2)),  "number" )
 end
 
 -- lume.randomchoice
@@ -94,6 +97,15 @@ tests["lume.randomchoice"] = function()
   testeq( lume.randomchoice({true}),    true )
 end
 
+-- lume.weightedchoice
+tests["lume.weightedchoice"] = function()
+  testeq( lume.weightedchoice( {a = 1} ),         "a" )
+  testeq( lume.weightedchoice( {a = 0, b = 1} ),  "b" )
+  tester.test.error( lume.weightedchoice, {}                  )
+  tester.test.error( lume.weightedchoice, { a = 0, b = 0 }    )
+  tester.test.error( lume.weightedchoice, { a = 1, b = -1 }   )
+end
+
 -- lume.shuffle
 tests["lume.shuffle"] = function()
   local t = {1, 2, 3, 4, 5}
@@ -103,7 +115,6 @@ tests["lume.shuffle"] = function()
   testeq( lume.shuffle({}), {}              )
 end
 
-
 -- lume.array
 tests["lume.array"] = function()
   local t = lume.array(pairs({a=0, b=0, c=0}))
@@ -151,12 +162,19 @@ end
 -- lume.reduce
 tests["lume.reduce"] = function()
   local concat = function(a, b) return a .. b end
+  local add = function(a, b) return a + b end
   testeq( lume.reduce({"cat", "dog"}, concat, ""),    "catdog"    )
   testeq( lume.reduce({"cat", "dog"}, concat, "pig"), "pigcatdog" )
+  testeq( lume.reduce({"me", "ow"}, concat),          "meow"      )
+  testeq( lume.reduce({1, 2, 3, 4}, add),             10          )
+  testeq( lume.reduce({1, 2, 3, 4}, add, 5),          15          )
+  testeq( lume.reduce({1}, add),                      1           )
+  testeq( lume.reduce({}, concat, "potato"),          "potato"    )
 end
 
 -- lume.set
 tests["lume.set"] = function()
+  testeq( lume.set({}), {} )
   local t = lume.set({1, 2, 3, 2, 5, 6, 6})
   table.sort(t)
   testeq( t, {1, 2, 3, 5, 6} )
@@ -186,15 +204,56 @@ tests["lume.find"] = function()
   testeq( lume.find({a=1, b=5, c=7}, 5),    "b" )
 end
 
+-- lume.match
+tests["lume.match"] = function()
+  local t = { "a", "b", "c", "d" }
+  local t2 = { a = 1, b = 2, c = 3, d = 4 }
+  local v, k = lume.match(t, function(x) return x > "c" end)
+  testeq( v, "d"  )
+  testeq( k, 4    )
+  local v, k = lume.match(t, function(x) return x < "b" end)
+  testeq( v, "a"  )
+  testeq( k, 1    )
+  local v, k = lume.match(t2, function(x) return x < 2 end)
+  testeq( v, 1    )
+  testeq( k, "a"  )
+  local v, k = lume.match(t2, function(x) return x > 5 end)
+  testeq( v, nil  )
+  testeq( k, nil  )
+end
+
+-- lume.count
+tests["lume.count"] = function()
+  local t = { a = 1, b = 2, c = 5, [13] = 22, z = 8 }
+  testeq( lume.count(t), 5 )
+  testeq( lume.count(t, function(x) return x % 2 == 0 end ), 3 )
+  local a = { 5, 6, 7, 8, 9 }
+  testeq( lume.count(a), #a )
+end
+
 -- lume.slice
 tests["lume.slice"] = function()
-  testeq( lume.slice({"a", "b", "c", "d", "e"}, 2, 4),  {"b", "c", "d"} )
-  testeq( lume.slice({"a", "b", "c", "d", "e"}, 2, -2), {"b", "c", "d"} )
-  testeq( lume.slice({"a", "b", "c", "d", "e"}, 3, -1), {"c", "d", "e"} )
-  testeq( lume.slice({"a", "b", "c", "d", "e"}, 3),     {"c", "d", "e"} )
-  testeq( lume.slice({"a", "b", "c", "d", "e"}, 4),     {"d", "e"}      )
-  testeq( lume.slice({"a", "b", "c", "d", "e"}, 1, 1),  {"a"}           )
-  testeq( lume.slice({"a", "b", "c", "d", "e"}, 2, 1),  {}              )
+  testeq( lume.slice({"a", "b", "c", "d", "e"}, 2, 4),    {"b", "c", "d"} )
+  testeq( lume.slice({"a", "b", "c", "d", "e"}, 2, -2),   {"b", "c", "d"} )
+  testeq( lume.slice({"a", "b", "c", "d", "e"}, 3, -1),   {"c", "d", "e"} )
+  testeq( lume.slice({"a", "b", "c", "d", "e"}, 3),       {"c", "d", "e"} )
+  testeq( lume.slice({"a", "b", "c", "d", "e"}, 4),       {"d", "e"}      )
+  testeq( lume.slice({"a", "b", "c", "d", "e"}, 1, 1),    {"a"}           )
+  testeq( lume.slice({"a", "b", "c", "d", "e"}, 2, 1),    {}              )
+  testeq( lume.slice({"a", "b", "c", "d", "e"}, -3, -2),  {"c", "d"}      )
+  testeq( lume.slice({"a", "b", "c", "d", "e"}, -3, 1),   {}              )
+  testeq( lume.slice({"a", "b", "c", "d", "e"}, 0, 1),    {"a"}           )
+  testeq( lume.slice({"a", "b", "c", "d", "e"}, 0, 0),    {}              )
+  testeq( lume.slice({"a", "b", "c", "d", "e"}, -3),      {"c", "d", "e"} )
+  testeq( lume.slice({"a", "b", "c", "d", "e"}, -3, 900), {"c", "d", "e"} )
+end
+
+-- lume.invert
+tests["lume_invert"] = function()
+  testeq( lume.invert({}),                        {}                  )
+  testeq( lume.invert{a = "x", b = "y"},          {x = "a", y = "b"}  )
+  testeq( lume.invert{a = 1, b = 2},              {"a", "b"}          )
+  testeq( lume.invert(lume.invert{a = 1, b = 2}), {a = 1, b = 2}      )
 end
 
 -- lume.clone
@@ -209,6 +268,7 @@ end
 tests["lume.fn"] = function()
   local f = lume.fn(function(a, b) return a + b end, 10)
   testeq( f(5),  15 )
+  tester.test.error( lume.fn, 123 )
 end
 
 -- lume.once
@@ -216,6 +276,35 @@ tests["lume.once"] = function()
   local f = lume.once(function(a, b) return a + b end, 10)
   testeq( f(5),  15   )
   testeq( f(5),  nil  )
+  tester.test.error( lume.once, 123 )
+end
+
+-- lume.memoize
+tests["lume.memoize"] = function()
+  local f = lume.memoize(
+    function(a, b, c)
+      return tostring(a) .. tostring(b) .. tostring(c)
+    end)
+  testeq( f("hello", nil, 15),  "hellonil15"  )
+  testeq( f("hello", nil, 15),  "hellonil15"  )
+  testeq( f(),                  "nilnilnil"   )
+  testeq( f(),                  "nilnilnil"   )
+  local f2 = lume.memoize(function() end)
+  testeq( f2(), nil )
+end
+
+-- lume.combine
+tests["lume.combine"] = function()
+  local acc = 0
+  local a = function(x, y) acc = acc + x + y end
+  local b = function(x, y) acc = acc + x * y end
+  local fn = lume.combine(a, b)
+  fn(10, 20)
+  testeq( acc, 230 )
+  acc = 0
+  fn = lume.combine(nil, a, nil, b, nil)
+  fn(10, 20)
+  testeq( acc, 230 )
 end
 
 -- lume.time
@@ -225,6 +314,21 @@ tests["lume.time"] = function()
   testeq( {a, b, c},  {50, 60, 70}  )
 end
 
+-- lume.lambda
+tests["lume.lambda"] = function()
+  testeq( lume.lambda "x->x*x"(10),                 100         )
+  testeq( lume.lambda "x->x*x"(20),                 400         )
+  testeq( lume.lambda "x,y -> 2*x+y"(10,5),         25          )
+  testeq( lume.lambda "a, b -> a / b"(1, 2),        .5          )
+  testeq( lume.lambda "a -> 'hi->' .. a"("doggy"),  "hi->doggy" )
+  testeq( lume.lambda "A1,_->A1.._"("te","st"),     "test"      )
+  testeq( lume.lambda "->"(1,2,3),                  nil         )
+  tester.test.error( lume.lambda, "abc"         )
+  tester.test.error( lume.lambda, ""            )
+  tester.test.error( lume.lambda, "a,b->a->b"   )
+  tester.test.error( lume.lambda, "(a),b->a+b"  )
+end
+
 -- lume.serialize / lume.deserialize
 tests["lume.serialize, lume.deserialize"] = function()
   local t = { 1, 2, 3, 4, true, false, "cat", "dog", {1, 2, 3} }
@@ -234,9 +338,15 @@ end
 
 -- lume.split
 tests["lume.split"] = function()
-  testeq( lume.split("cat   dog  pig"),     {"cat", "dog", "pig"} )
-  testeq( lume.split(",cat,dog,pig", ","),  {"cat", "dog", "pig"} )
-  testeq( lume.split(",cat,dog;pig", ",;"), {"cat", "dog", "pig"} )
+  testeq( lume.split("cat   dog  pig"),     {"cat", "dog", "pig"}     )
+  testeq( lume.split("cat,dog,pig", ","),   {"cat", "dog", "pig"}     )
+  testeq( lume.split("cat,dog;pig", ";"),   {"cat,dog", "pig"}        )
+  testeq( lume.split("cat,dog,,pig", ","),  {"cat", "dog", "", "pig"} )
+  testeq( lume.split(";;;cat;", ";"),       {"", "", "", "cat", ""}   )
+  testeq( lume.split("cat.dog", "."),       {"cat", "dog"}            )
+  testeq( lume.split("cat%dog", "%"),       {"cat", "dog"}            )
+  testeq( lume.split("1<>2<>3", "<>"),      {"1", "2", "3"}           )
+  tester.test.error( lume.split, "abc", "" )
 end
 
 -- lume.trim
@@ -244,6 +354,8 @@ tests["lume.trim"] = function()
   testeq( lume.trim("   hello world   "),       "hello world"   )
   testeq( lume.trim("-=-hello-world===", "-="), "hello-world"   )
   testeq( lume.trim("***hello world*-*", "*"),  "hello world*-" )
+  testeq( lume.trim("...hello world.", "."),    "hello world"   )
+  testeq( lume.trim("^.hello world]^", "^.]"),  "hello world"   )
 end
 
 -- lume.format
@@ -265,11 +377,11 @@ tests["lume.trace"] = function()
   print = function(x)
     file, line, msg = x:match("%[(.-):(.-)%] (.*)")
   end
-  lume.trace("Hi world")
+  lume.trace("Hi world", 123.456, 1, nil)
   print = oldprint
-  testeq( file:match(".lua$"),    ".lua"      )
-  testeq( tonumber(line) ~= nil,  true        ) 
-  testeq( msg,                    "Hi world"  )
+  testeq( file:match(".lua$"),    ".lua"                  )
+  testeq( tonumber(line) ~= nil,  true                    ) 
+  testeq( msg,                    "Hi world 123.46 1 nil" )
 end
 
 -- lume.dostring
@@ -278,6 +390,12 @@ tests["lume.dostring"] = function()
   testeq( lume.dostring([[return 12345]]),    12345     )   
 end
 
+-- lume.uuid
+tests["lume.uuid"] = function()
+  testeq( type(lume.uuid()), "string" )
+  testeq( #lume.uuid(),      36       )
+end
+
 -- lume.hotswap
 tests["lume.hotswap"] = function()
   local ok, err = lume.hotswap("bad_module_name")
@@ -294,6 +412,13 @@ tests["lume.rgba"] = function()
   testeq( b, 0x78 )
 end
 
+-- lume.chain
+tests["lume.chain"] = function()
+  local t = lume.chain({1, 2}):map(function(x) return x * 2 end):result() 
+  testeq( t, { 2, 4 } )
+  testeq( lume.chain(10):result(), 10 )
+end
+
 
 tester.dotests(tests)
 tester.test.global()

test/tester.lua

@@ -128,6 +128,18 @@ function tester.test.equal(result, expected)
 end
 
 
+function tester.test.error(fn, ...)
+  local passed = not pcall(fn, ...)
+  local info = debug.getinfo(2)
+  if passed then
+    dopass(info.short_src, info.currentline)
+  else
+    dofail(info.short_src, info.currentline)
+    printfailmsg("Expected an error to be raised")
+  end
+end
+
+
 function tester.dotests(t)
   local keys = {}
   for k in pairs(t) do table.insert(keys, k) end