diff --git a/docs/reference.md b/docs/reference.md index 022e9a4..9084022 100644 --- a/docs/reference.md +++ b/docs/reference.md @@ -16,27 +16,32 @@ already defined will be declared as local to the scope of that declaration. If you wish to create a global variable it must be done using the `export` keyword. + ```moon hello = "world" a,b,c = 1, 2, 3 - + ``` ## Update Assignment `+=`, `-=`, `/=`, `*=`, `%=`, `..=` operators have been added for updating a value by a certain amount. They are aliases for their expanded equivalents. + ```moon x = 0 x += 10 s = "hello " s ..= "world" + ``` ## Comments Like Lua, comments start with `--` and continue to the end of the line. Comments are not written to the output. + ```moon -- I am a comment + ``` ## Literals & Operators @@ -51,61 +56,79 @@ MoonScript also supports all the same binary and unary operators. Additionally All functions are created using a function expression. A simple function is denoted using the arrow: `->` + ```moon my_function = -> my_function() -- call the empty function + ``` The body of the function can either be one statement placed directly after the arrow, or it can be a series of statements indented on the following lines: + ```moon func_a = -> print "hello world" func_b = -> value = 100 print "The value:", value + ``` If a function has no arguments, it can be called using the `!` operator, instead of empty parentheses. The `!` invocation is the preferred way to call functions with no arguments. + ```moon func_a! func_b() + ``` Functions with arguments can be created by preceding the arrow with a list of argument names in parentheses: + ```moon sum = (x, y) -> print "sum", x + y + ``` Functions can be called by listing the values of the arguments after the name of the variable where the function is stored. When chaining together function calls, the arguments are applied to the closest function to the left. + ```moon sum 10, 20 print sum 10, 20 a b c "a", "b", "c" + ``` In order to avoid ambiguity in when calling functions, parentheses can also be used to surround the arguments. This is required here in order to make sure the right arguments get sent to the right functions. + ```moon print "x:", sum(10, 20), "y:", sum(30, 40) + ``` Functions will coerce the last statement in their body into a return statement, this is called implicit return: + ```moon sum = (x, y) -> x + y print "The sum is ", sum 10, 20 + ``` And if you need to explicitly return, you can use the `return` keyword: + ```moon sum = (x, y) -> return x + y + ``` Just like in Lua, functions can return multiple values. The last statement must be a list of values separated by commas: + ```moon mystery = (x, y) -> x + y, x - y a,b = mystery 10, 20 + ``` ### Fat Arrows @@ -113,7 +136,9 @@ Because it is an idiom in Lua to send an object as the first argument when calling a method, a special syntax is provided for creating functions which automatically includes a `self` argument. + ```moon func = (num) => self.value + num + ``` ### Argument Defaults @@ -121,16 +146,20 @@ It is possible to provide default values for the arguments of a function. An argument is determined to be empty if it's value is `nil`. Any `nil` arguments that have a default value will be replace before the body of the function is run. + ```moon my_function = (name="something", height=100) -> print "Hello I am", name print "My height is", height + ``` An argument default value expression is evaluated in the body of the function in the order of the argument declarations. For this reason default values have access to previously declared arguments. + ```moon some_args = (x=100, y=x+1000) -> print x + y + ``` ### Considerations @@ -143,9 +172,11 @@ subtraction operator. In order to force subtraction a space must be placed after the `-` operator. In order to force a negation, no space must follow the `-`. Consider the examples below. + ```moon a = x - 10 b = x-10 c = x -y + ``` The precedence of the first argument of a function call can also be controlled using whitespace if the argument is a literal string.In Lua, it is common to @@ -159,8 +190,10 @@ Where there is a space following a variable and a string literal, the function call acts as show above. The string literal belongs to any following expressions (if they exist), which serves as the argument list. + ```moon x = func"hello" + 100 y = func "hello" + 100 + ``` ### Multi-line arguments @@ -174,6 +207,7 @@ must end in a comma. And the following line must be indented more than the current indentation. Once indented, all other argument lines must be at the same level of indentation to be part of the argument list + ```moon my_func 5,4,3, 8,9,10 @@ -181,38 +215,45 @@ same level of indentation to be part of the argument list 3,4, 5,6, 7,8 + ``` This type of invocation can be nested. The level of indentation is used to determine to which function the arguments belong to. - + ```moon my_func 5,6,7, 6, another_func 6,7,8, 9,1,2, 5,4 + ``` Because [tables](#table_literals) also use the comma as a delimiter, this indentation syntax is helpful for letting values be part of the argument list instead of being part of the table. + ```moon x = { 1,2,3,4, a_func 4,5, 5,6, 8,9,10 } + ``` Although uncommon, notice how we can give a deeper indentation for function arguments if we know we will be using a lower indentation futher on. + ```moon y = { my_func 1,2,3, 4,5, 5,6,7 } + ``` The same thing can be done with other block level statements like [conditionals](#conditionals). We can use indentation level to determine what statement a value belongs to: + ```moon if func 1,2,3, "hello", "world" @@ -224,62 +265,76 @@ statement a value belongs to: "world" print "hello" print "I am inside if" - + ``` ## Table Literals Like in Lua, tables are delimited in curly braces. + ```moon some_values = { 1, 2, 3, 4 } + ``` Unlike Lua, assigning a value to a key in a table is done with `:` (instead of `=`). + ```moon some_values = { name: "Bill", age: 200, ["favorite food"]: "rice" } + ``` The curly braces can be left off if a single table of key value pairs is being assigned. + ```moon profile = height: "4 feet", shoe_size: 13, favorite_foods: {"ice cream", "donuts"} + ``` Newlines can be used to delimit values instead of a comma (or both): + ```moon values = { 1,2,3,4 5,6,7,8 name: "superman" occupation: "crime fighting" } + ``` When creating a single line table literal, the curly braces can also be left off: + ```moon my_function dance: "Tango", partner: "none" y = type: "dog", legs: 4, tails: 1 + ``` The keys of a table literal can be language keywords without being escaped: + ```moon tbl = { do: "something" end: "hunger" } + ``` If you are constructing a table out of variables and wish the keys to be the same as the variable names, then the `:` prefix operator can be used: + ```moon hair = "golden" height = 200 person = { :hair, :height, shoe_size: 40 } print_table :hair, :height + ``` ## Comprehensions @@ -295,28 +350,36 @@ value on each iteration. The following creates a copy of the `items` table but with all the values doubled. + ```moon items = { 1, 2, 3, 4 } doubled = [item * 2 for i, item in ipairs items] + ``` The items included in the new table can be restricted with a `when` clause: + ```moon iter = ipairs items slice = [item for i, item in iter when i > 1 and i < 3] + ``` Because it is common to iterate over the values of a numerically indexed table, an `*` operator is introduced. The doubled example can be rewritten as: + ```moon doubled = [item * 2 for item in *items] + ``` The `for` and `when` clauses can be chained as much as desired. The only requirement is that a comprehension has at least one `for` clause. Using multiple `for` clauses is the same as using nested loops: + ```moon x_coords = {4, 5, 6, 7} y_coords = {9, 2, 3} points = [{x,y} for x in *x_coords for y in *y_coords] + ``` ### Table Comprehensions @@ -325,6 +388,7 @@ The syntax for table comprehensions is very similar, differing by using `{` and This example copies the key-value table `thing`: + ```moon thing = { color: "red" name: "fast" @@ -332,18 +396,23 @@ This example copies the key-value table `thing`: } thing_copy = {k,v for k,v in pairs thing} + ``` Table comprehensions, like list comprehensions, also support multiple `for` and -`when` clauses`. In this example we use a `where` clause to prevent the value +`when` clauses. In this example we use a `where` clause to prevent the value associated with the `color` key from being copied. + ```moon no_color = {k,v for k,v in pairs thing when k != "color"} + ``` The `*` operator is also supported. Here we create a square root look up table for a few numbers. + ```moon numbers = {1,2,3,4} sqrts = {i, math.sqrt i for i in *numbers} + ``` ### Slicing @@ -354,24 +423,31 @@ a step size in a `for` loop. Here we can set the minimum and maximum bounds, taking all items with indexes between 1 and 5 inclusive: + ```moon slice = [item for item in *items[1:5]] + ``` Any of the slice arguments can be left off to use a sensible default. In this example, if the max index is left off it defaults to the length of the table. This will take everything but the first element: + ```moon slice = [item for item in *items[2:]] + ``` If the minimum bound is left out, it defaults to 1. Here we only provide a step size and leave the other bounds blank. This takes all odd indexed items: (1, 3, 5, ...) + ```moon slice = [item for items in *items[::2]] + ``` ## For Loop There are two for loop forms, just like in Lua. A numeric one and a generic one: + ```moon for i = 10, 20 print i @@ -380,18 +456,23 @@ There are two for loop forms, just like in Lua. A numeric one and a generic one: for key, value in pairs object print key, value + ``` The slicing and `*` operators can be used, just like with table comprehensions: + ```moon for item in *items[2:4] print item + ``` A shorter syntax is also available for all variations when the body is only a single line: + ```moon for item in *items do print item for j = 1,10,3 do print j + ``` A for loop can also be used an expression. The last statement in the body of the for loop is coerced into an expression and appended to an accumulating @@ -399,28 +480,34 @@ table if the value of that expression is not nil. Doubling every even number: + ```moon doubled_evens = for i=1,20 if i % 2 == 0 i * 2 else i + ``` Filtering out odd numbers: + ```moon my_numbers = {1,2,3,4,5,6} odds = for x in *my_numbers if x % 2 == 1 then x + ``` For loops at the end of a function body are not accumulated into a table for a return value (Instead the function will return `nil`). Either an explicit `return` statement can be used, or the loop can be converted into a list comprehension. + ```moon func_a = -> for i=1,10 do i func_b = -> return for i=1,10 do i print func_a! -- prints nil print func_b! -- prints table object + ``` This is done to avoid the needless creation of tables for functions that don't need to return the results of the loop. @@ -429,12 +516,14 @@ need to return the results of the loop. The while loop also comes in two variations: + ```moon i = 10 while i > 0 print i i -= 1 while running == true do my_function! + ``` Like for loops, the while loop can also be used an expression. Additionally, for a function to return the accumulated value of a while loop, the statement @@ -442,25 +531,31 @@ must be explicitly returned. ## Conditionals + ```moon have_coins = false if have_coins print "Got coins" else print "No coins" + ``` A short syntax for single statements can also be used: + ```moon have_coins = false if have_coins then print "Got coins" else print "No coins" - + ``` Because if statements can be used as expressions, this can able be written as: + ```moon have_coins = false print if have_coins then "Got coins" else "No coins" + ``` Conditionals can also be used in return statements and assignments: + ```moon is_tall = (name) -> if name == "Rob" true @@ -473,18 +568,22 @@ Conditionals can also be used in return statements and assignments: "I am not so tall" print message -- prints: I am very tall - + ``` ## Line Decorators For convenience, the for loop and if statement can be applied to single statements at the end of the line: + ```moon print "hello world" if name == "Rob" + ``` And with basic loops: + ```moon print "item: ", item for item in *items + ``` ## Switch @@ -493,6 +592,7 @@ check against the same value. Note that the value is only evaluated once. Like if statements, switches can have an else block to handle no matches. Comparison is done with the `==` operator. + ```moon name = "Dan" switch name case "Robert" @@ -501,10 +601,12 @@ is done with the `==` operator. print "Your name, it's Dan" else print "I don't know about your name" + ``` Switches can be used as expressions as well, here we can assign the result of the switch to a variable: + ```moon b = 1 next_number = switch b case 1 @@ -513,14 +615,17 @@ the switch to a variable: 3 else error "can't count that high!" + ``` We can use the `then` keyword to write a switch case's block on a single line. No extra keyword is needed to write the else block on a single line. + ```moon msg = switch math.random(1, 5) case 1 then "you are lucky" case 2 then "you are almost lucky" else "not so lucky" + ``` It is worth noting the order of the case comparison expression. The case's expression is on the left hand side. This can be useful if the case's @@ -535,6 +640,7 @@ code if you wish to know the implementation details. A simple class: + ```moon class Inventory new: => @items = {} @@ -544,6 +650,7 @@ A simple class: @items[name] += 1 else @items[name] = 1 + ``` A class is declared with a `class` statement followed by a table-like declaration where all of the methods and properties are listed. @@ -560,9 +667,11 @@ The `@` prefix on a variable name is shorthand for `self.`. `@items` becomes Creating an instance of the class is done by calling the name of the class as a function. + ```moon inv = Inventory! inv\add_item "t-shirt" inv\add_item "pants" + ``` Because the instance of the class needs to be sent to the methods when they are called, the '\' operator is used. @@ -573,6 +682,7 @@ functions, but for other types of objects, undesired results may occur. Consider the example below, the `clothes` property is shared amongst all instances, so modifications to it in one instance will show up in another: + ```moon class Person clothes: {} give_item: (name) => @@ -586,24 +696,29 @@ instances, so modifications to it in one instance will show up in another: -- will print both pants and shirt print item for item in *a.clothes + ``` The proper way to avoid this problem is to create the mutable state of the object in the constructor: + ```moon class Person new: => @clothes = {} + ``` ### Inheritance The `extends` keyword can be used in a class declaration to inherit the properties and methods from another class. + ```moon class BackPack extends Inventory size: 10 add_item: (name) => if #@items > size then error "backpack is full" super name + ``` Here we extend our Inventory class, and limit the amount of items it can carry. @@ -629,6 +744,7 @@ retrieve a function, the raw function is returned. A few examples of using `super` in different ways: + ```moon class MyClass extends ParentClass a_method: => -- the following have the same effect: @@ -638,23 +754,24 @@ A few examples of using `super` in different ways: -- super as a value is equal to the parent class: assert super == ParentClass + ``` `super` can also be used on left side of a [Function Stub](#function_stubs). The only major difference is that instead of the resulting function being bound to the value of `super`, it is bound to `self`. ### Types - Every instance of a class carries its type with it. This is stored in the special `__class` property. This property holds the class object. The class object is what we call to build a new instance. We can also index the class object to retrieve class methods and properties. + ```moon b = BackPack! assert b.__class == BackPack print BackPack.size -- prints 10 - + ``` ## Export Statement @@ -664,13 +781,16 @@ be declared as local, special syntax is required to declare a variable globally. The export keyword makes it so any following assignments to the specified names will not be assigned locally. + ```moon export var_name, var_name2 var_name, var_name3 = "hello", "world" + ``` This is especially useful when declaring what will be externally visible in a module: + ```moon -- my_module.moon module "my_module", package.seeall export print_result @@ -686,11 +806,14 @@ module: my_module.print_result 4, 5 -- prints the result print my_module.length 6, 7 -- errors, `length` not visible + ``` Assignment can be combined with the export keyword to assign to global variables directly: + ```moon export some_number, message_str = 100, "hello world" + ``` Additionally, a class declaration can be prefixed with the export keyword in order to export it. @@ -708,16 +831,21 @@ capital letter. Often you want to bring some values from a table into the current scope as local variables by their name. The import statement lets us accomplish this: + ```moon import insert from table + ``` The multiple names can be given, each separated by a comma: + ```moon import C, Ct, Cmt from lpeg + ``` Sometimes a function requires that the table be sent in as the first argument (when using the \\ syntax). As a shortcut, we can prefix the name with a \\ to bind it to that table: + ```moon -- some object my_module = state: 100 @@ -727,6 +855,7 @@ with a \\ to bind it to that table: import \add from my_module print add(22) -- equivalent to calling my_module\get 22 + ``` ## With Statement @@ -744,26 +873,32 @@ those operations applied to the object we are using `with` on. For example, we work with a newly created object: + ```moon with Person! .name = "Oswald" \add_relative my_dad \save! print .name + ``` The `with` statement can also be used as an expression which returns the value it has been giving access to. + ```moon file = with File "favorite_foods.txt" \set_encoding "utf8" + ``` Or... + ```moon create_person = (name, relatives) -> with Person! .name = name \add_relative relative for relative in *relatives me = create_person "Leaf", {dad, mother, sister} + ``` ## Function Stubs @@ -779,6 +914,7 @@ function in the correct context of the object. Its syntax is the same as calling an instance method with the \\ operator but with no argument list provided. + ```moon my_object = { value: 1000 write: => print "the value:", @value @@ -795,6 +931,7 @@ with no argument list provided. -- function stub syntax -- lets us bundle the object into a new function run_callback my_object\write + ``` ## The Using Clause; Controlling Destructive Assignment @@ -802,6 +939,7 @@ While lexical scoping can be a great help in reducing the complexity of the code we write, things can get unwieldy as the code size increases. Consider the following snippet: + ```moon i = 100 -- many lines of code... @@ -815,6 +953,7 @@ the following snippet: my_func() print i -- will print 0 + ``` In `my_func`, we've overwritten the value of `i` mistakenly. In this example it @@ -828,6 +967,7 @@ The `using` keyword lets us do that. `using nil` makes sure that no closed variables are overwritten in assignment. The `using` clause is placed after the argument list in a function, or in place of it if there are no arguments. + ```moon i = 100 my_func = (using nil) -> @@ -835,11 +975,13 @@ argument list in a function, or in place of it if there are no arguments. my_func() print i -- prints 100, i is unaffected + ``` Multiple names can be separated by commas. Closure values can still be accessed, they just cant be modified: + ```moon tmp = 1213 i, k = 100, 50 @@ -850,7 +992,7 @@ accessed, they just cant be modified: my_func(22) print i,k -- these have been updated - + ``` # MoonScript API @@ -859,7 +1001,9 @@ accessed, they just cant be modified: Upon installing MoonScript, a `moonscript` module is made available. The best use of this module is making your Lua's require function MoonScript aware. + ```moon require "moonscript" + ``` After `moonscript` is required, Lua's package loader is updated to search for `.moon` files on any subsequent calls to `require`. The search path for `.moon` @@ -889,8 +1033,10 @@ can make debugging particularly difficult. Consider the following file with a bug: + ```moon add_numbers = (x,y) -> x + z print add_numbers 10,0 + ``` The following error is generated: @@ -914,6 +1060,7 @@ Lua code from MoonScript code. Here is a quick example of how you would compile a MoonScript string to a Lua String: + ```moon require "moonscript.parse" require "moonscript.compile" @@ -931,7 +1078,7 @@ String: -- our code is ready print lua_code - + ``` # Command Line Use @@ -946,7 +1093,9 @@ Two tools are installed with MoonScript, `moon` and `moonc`. without needing a separate compile step. All MoonsScript files are compiled in memory as they are run. - ~> moon my_script.moon + ```bash + $ moon my_script.moon + ``` Any MoonScript files that are required will also be compiled and run automatically. @@ -965,7 +1114,9 @@ flag. It takes a list of files, compiles them all, and creates the associated `.lua` files in the same directories. - ~> moonc my_script1.moon my_script2.moon ... + ```bash + $ moonc my_script1.moon my_script2.moon ... + ``` You can control where the compiled files are put using the `-t` flag, followed by a directory. @@ -983,24 +1134,24 @@ A full list of flags can be seen by passing the `-h` or `--help` flag. # License (MIT) -Copyright (C) 2011 by Leaf Corcoran - -Permission is hereby granted, free of charge, to any person obtaining a copy -of this software and associated documentation files (the "Software"), to deal -in the Software without restriction, including without limitation the rights -to use, copy, modify, merge, publish, distribute, sublicense, and/or sell -copies of the Software, and to permit persons to whom the Software is -furnished to do so, subject to the following conditions: - -The above copyright notice and this permission notice shall be included in -all copies or substantial portions of the Software. - -THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR -IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, -FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE -AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER -LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, -OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN -THE SOFTWARE. + Copyright (C) 2011 by Leaf Corcoran + + Permission is hereby granted, free of charge, to any person obtaining a copy + of this software and associated documentation files (the "Software"), to deal + in the Software without restriction, including without limitation the rights + to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + copies of the Software, and to permit persons to whom the Software is + furnished to do so, subject to the following conditions: + + The above copyright notice and this permission notice shall be included in + all copies or substantial portions of the Software. + + THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE + AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN + THE SOFTWARE.