documentation updates to reflect removal of the let keyword

also some general cleanups and improvements

docs/system.dj

@@ -25,8 +25,6 @@ Operators may have one or two arguments, where one argument corresponds to a pre
 Note that this documentation lists a unary and binary operator of the same spelling as _two separate functions_, not overloads of a single function.
 
 The argument name usually does not matter when calling the function - it is only used for documentation purposes.
-The one exception is arguments called `...`, which signify that zero or more arguments can be passed to the function at that position.
-(Currently there are no functions that accept any number of arguments, though.)
 
 The argument _type_ however is important.
 If you try to use a function with the wrong type of value as its argument, it will fail with an error.
@@ -567,7 +565,7 @@ For example, consider multiplicatively blending two colors.
 ```haku
 -- This is how you can multiply two colors together.
 -- Note that the `*` operator works for colors, so you don't need to define this in your brushes.
-mulRgba = \a, b ->
+mulRgba: \a, b ->
   rgba (rgbaR a * rgbaR b) (rgbaG a * rgbaG b) (rgbaB a * rgbaB b) (rgbaA a * rgbaA b)
 ```
 
@@ -575,11 +573,11 @@ If haku represented colors using an 8-bit `0` to `255` range instead, to multipl
 
 ```haku
 -- NOTE: This example does NOT work correctly.
-mulRgba = \a, b ->
-  let red = (rgbaR a * rgbaR b) / 255
-  let green = (rgbaG a * rgbaG b) / 255
-  let blue = (rgbaB a * rgbaB b) / 255
-  let alpha = (rgbaA a * rgbaA b) / 255
+mulRgba: \a, b ->
+  red = (rgbaR a * rgbaR b) / 255
+  green = (rgbaG a * rgbaG b) / 255
+  blue = (rgbaB a * rgbaB b) / 255
+  alpha = (rgbaA a * rgbaA b) / 255
   rgba red green blue alpha
 ```
 
@@ -683,32 +681,38 @@ Some of these operations may be a bit confusing, so here are some examples.
 
 ```haku
 -- To add two to all elements in a list:
-list = range 1 4  -- [1, 2, 3, 4]
-twoAdded = map list \x ->
+list: range 1 4  -- [1, 2, 3, 4]
+twoAdded: map list \x ->
   x + 2
+-- [3, 4, 5, 6]
 ```
 
 ```haku
 -- To filter out only even numbers in a list:
-list = range 1 10
-isEven = \x -> mod x 2 == 0
-onlyEven = filter list isEven
+list: range 1 10 -- [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
+isEven: \x -> mod x 2 == 0
+onlyEven: filter list isEven
+-- [2, 4, 6, 8, 10]
 ```
 
 ```haku
 -- To sum all the numbers in a list:
-list = [1, 3, 10, 2, 30, 4, 1]
-sum = reduce list 0 \acc, value -> acc + value
+list: [1, 3, 10, 2, 30, 4, 1]
+sum: reduce list 0 \acc, value -> acc + value
+-- 51
 ```
 
 ```haku
 -- To flatten a singly-nested list:
-list = [[1, 2], [3, 4], [5, 6]]
-flatList = flatten list  -- [1, 2, 3, 4, 5, 6]
+list: [[1, 2], [3, 4], [5, 6]]
+flatList: flatten list  -- [1, 2, 3, 4, 5, 6]
 
 -- Note that this only applies to a single level of nesting:
-deepList = [[[1, 2, 3, 4]]]
-lessDeepList = flatten deepList  -- [[1, 2, 3, 4]]
+deepList: [[[1, 2, 3, 4]]]
+lessDeepList: flatten deepList  -- [[1, 2, 3, 4]]
+
+-- This can be used to join lists together without nesting:
+join: \a, b -> flatten [a, b]
 ```