Version 1.4.0

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)
@@ -208,6 +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.
@@ -215,16 +234,6 @@ 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.combine(...)
-Creates a wrapper function which calls each supplied argument in the order they
-were passed to `lume.combine`. 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.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

lume.lua

@@ -7,7 +7,7 @@
 -- under the terms of the MIT license. See LICENSE for details.
 --
 
-local lume = { _version = "1.3.1" }
+local lume = { _version = "1.4.0" }
 
 local pairs, ipairs = pairs, ipairs
 local type, assert, unpack = type, assert, unpack or table.unpack
@@ -30,7 +30,9 @@ local absindex = function(len, i)
 end
 
 local iscallable = function(x)
-  return type(x) == "function" or getmetatable(x).__call ~= nil
+  if type(x) == "function" then return true end
+  local mt = getmetatable(x)
+  return mt and mt.__call ~= nil
 end
 
 
@@ -57,7 +59,8 @@ 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
 
@@ -267,22 +270,46 @@ function lume.once(fn, ...)
 end
 
 
-function lume.time(fn, ...)
-  local start = os.clock()
-  local rtn = {fn(...)}
-  return (os.clock() - start), unpack(rtn)
+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 = {...}
-  assert(lume.all(funcs, iscallable), "expected all arguments to be functions")
+  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(...)}
+  return (os.clock() - start), unpack(rtn)
+end
+
+
 local lambda_cache = {}
 
 function lume.lambda(str)
@@ -408,9 +435,9 @@ end
 
 
 function lume.rgba(color)
-  local a = math_floor((color / 2 ^ 24) % 256)
-  local r = math_floor((color / 2 ^ 16) % 256)
-  local g = math_floor((color / 2 ^ 08) % 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

test/test_lume.lua

@@ -279,11 +279,18 @@ tests["lume.once"] = function()
   tester.test.error( lume.once, 123 )
 end
 
--- lume.time
-tests["lume.time"] = function()
-  local t, a, b, c = lume.time(function(x) return 50, 60, x end, 70)
-  testeq( type(t),    "number"      )
-  testeq( {a, b, c},  {50, 60, 70}  )
+-- 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
@@ -294,6 +301,17 @@ tests["lume.combine"] = function()
   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
+tests["lume.time"] = function()
+  local t, a, b, c = lume.time(function(x) return 50, 60, x end, 70)
+  testeq( type(t),    "number"      )
+  testeq( {a, b, c},  {50, 60, 70}  )
 end
 
 -- lume.lambda