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diff --git a/neat.html.markdown b/neat.html.markdown new file mode 100644 index 00000000..6a319a7d --- /dev/null +++ b/neat.html.markdown @@ -0,0 +1,299 @@ +--- + +language: neat +contributors: + - ["Feep", "https://github.com/FeepingCreature"] +filename: LearnNeat.nt + +--- + +Neat is basically a smaller version of D1 with some experimental syntax and a focus on terseness without losing the basic C-like syntax. + +[Read more here.](https://github.com/FeepingCreature/fcc/wiki) + +```D +// single line comments start with // +/* + multiline comments look like this +*/ +/+ + or this + /+ these can be nested too, same as D +/ ++/ + +// Module name. This has to match the filename/directory. +module LearnNeat; + +// Make names from another module visible in this one. +import std.file; +// You can import multiple things at once. +import std.math, std.util; +// You can even group up imports! +import std.(process, socket); + +// Global functions! +void foo() { } + +// Main function, same as in C. +// string[] == "array of strings". +// "string" is just an alias for char[], +void main(string[] args) { + // Call functions with "function expression". + writeln "Hello World"; + // You can do it like in C too... if you really want. + writeln ("Hello World"); + // Declare a variable with "type identifier" + string arg = ("Hello World"); + writeln arg; + // (expression, expression) forms a tuple. + // There are no one-value tuples though. + // So you can always use () in the mathematical sense. + // (string) arg; <- is an error + + /* + byte: 8 bit signed integer + char: 8 bit UTF-8 byte component. + short: 16 bit signed integer + int: 32 bit signed integer + long: 64 bit signed integer + + float: 32 bit floating point + double: 64 bit floating point + real: biggest native size floating point (80 bit on x86). + + bool: true or false + */ + int a = 5; + bool b = true; + // as in C, && and || are short-circuit evaluating. + b = b && false; + assert(b == false); + // "" are "format strings". So $variable will be substituted at runtime + // with a formatted version of the variable. + writeln "$a"; + // This will just print $a. + writeln `$a`; + // you can format expressions with $() + writeln "$(2+2)"; + // Note: there is no special syntax for characters. + char c = "a"; + // Cast values by using type: expression. + // There are three kinds of casts: + // casts that just specify conversions that would be happening automatically + // (implicit casts) + float f = float:5; + float f2 = 5; // would also work + // casts that require throwing away information or complicated computation - + // those must always be done explicitly + // (conversion casts) + int i = int:f; + // int i = f; // would not work! + // and, as a last attempt, casts that just reinterpret the raw data. + // Those only work if the types have the same size. + string s = "Hello World"; + // Arrays are (length, pointer) pairs. + // This is a tuple type. Tuple types are (type, type, type). + // The type of a tuple expression is a tuple type. (duh) + (int, char*) array = (int, char*): s; + // You can index arrays and tuples using the expression[index] syntax. + writeln "pointer is $(array[1]) and length is $(array[0])"; + // You can slice them using the expression[from .. to] syntax. + // Slicing an array makes another array. + writeln "$(s[0..5]) World"; + // Alias name = expression gives the expression a name. + // As opposed to a variable, aliases do not have an address + // and can not be assigned to. (Unless the expression is assignable) + alias range = 0 .. 5; + writeln "$(s[range]) World"; + // You can iterate over ranges. + for int i <- range { + write "$(s[i])"; + } + writeln " World"; + // Note that if "range" had been a variable, it would be 'empty' now! + // Range variables can only be iterated once. + // The syntax for iteration is "expression <- iterable". + // Lots of things are iterable. + for char c <- "Hello" { write "$c"; } + writeln " World"; + // For loops are "for test statement"; + alias test = char d <- "Hello"; + for test write "$d"; + writeln " World\t\x05"; // note: escapes work + // Pointers: function the same as in C, btw. The usual. + // Do note: the pointer star sticks with the TYPE, not the VARIABLE! + string* p; + assert(p == null); // default initializer + p = &s; + writeln "$(*p)"; + // Math operators are (almost) standard. + int x = 2 + 3 * 4 << 5; + // Note: XOR is "xor". ^ is reserved for exponentiation (once I implement that). + int y = 3 xor 5; + int z = 5; + assert(z++ == 5); + assert(++z == 7); + writeln "x $x y $y z $z"; + // As in D, ~ concatenates. + string hewo = "Hello " ~ "World"; + // == tests for equality, "is" tests for identity. + assert (hewo == s); + assert !(hewo is s); + // same as + assert (hewo !is s); + + // Allocate arrays using "new array length" + int[] integers = new int[] 10; + assert(integers.length == 10); + assert(integers[0] == 0); // zero is default initializer + integers = integers ~ 5; // This allocates a new array! + assert(integers.length == 11); + + // This is an appender array. + // Instead of (length, pointer), it tracks (capacity, length, pointer). + // When you append to it, it will use the free capacity if it can. + // If it runs out of space, it reallocates - but it will free the old array automatically. + // This makes it convenient for building arrays. + int[auto~] appender; + appender ~= 2; + appender ~= 3; + appender.free(); // same as {mem.free(appender.ptr); appender = null;} + + // Scope variables are automatically freed at the end of the current scope. + scope int[auto~] someOtherAppender; + // This is the same as: + int[auto~] someOtherAppender2; + onExit { someOtherAppender2.free; } + + // You can do a C for loop too + // - but why would you want to? + for (int i = 0; i < 5; ++i) { } + // Otherwise, for and while are the same. + while int i <- 0..4 { + assert(i == 0); + break; // continue works too + } then assert(false); // if we hadn't break'd, this would run at the end + // This is the height of loopdom - the produce-test-consume loop. + do { + int i = 5; + } while (i == 5) { + assert(i == 5); + break; // otherwise we'd go back up to do { + } + + // This is a nested function. + // Nested functions can access the surrounding function. + string returnS() { return s; } + writeln returnS(); + + // Take the address of a function using & + // The type of a global function is ReturnType function(ParameterTypeTuple). + void function() foop = &foo; + + // Similarly, the type of a nested function is ReturnType delegate(ParameterTypeTuple). + string delegate() returnSp = &returnS; + writeln returnSp(); + // Class member functions and struct member functions also fit into delegate variables. + // In general, delegates are functions that carry an additional context pointer. + // ("fat pointers" in C) + + // Allocate a "snapshot" with "new delegate". + // Snapshots are not closures! I used to call them closures too, + // but then my Haskell-using friends yelled at me so I had to stop. + // The difference is that snapshots "capture" their surrounding context + // when "new" is used. + // This allows things like this + int delegate(int) add(int a) { + int add_a(int b) { return a + b; } + // This does not work - the context of add_a becomes invalid + // when add returns. + // return &add_a; + // Instead: + return new &add_a; + } + int delegate(int) dg = add 2; + assert (dg(3) == 5); + // or + assert (((add 2) 3) == 5); + // or + assert (add 2 3 == 5); + // add can also be written as + int delegate(int) add2(int a) { + // this is an implicit, nameless nested function. + return new λ(int b) { return a + b; } + } + // or even + auto add3(int a) { return new λ(int b) -> a + b; } + // hahahaaa + auto add4 = λ(int a) -> new λ(int b) -> a + b; + assert(add4 2 3 == 5); + // If your keyboard doesn't have a λ (you poor sod) + // you can use \ too. + auto add5 = \(int a) -> new \(int b) -> a + b; + // Note! + auto nestfun = λ() { } // There is NO semicolon needed here! + // "}" can always substitute for "};". + // This provides syntactic consistency with built-in statements. + + + // This is a class. + // Note: almost all elements of Neat can be used on the module level + // or just as well inside a function. + class C { + int a; + void writeA() { writeln "$a"; } + // It's a nested class - it exists in the context of main(). + // so if you leave main(), any instances of C become invalid. + void writeS() { writeln "$s"; } + } + C cc = new C; + // cc is a *reference* to C. Classes are always references. + cc.a = 5; // Always used for property access. + auto ccp = &cc; + (*ccp).a = 6; + // or just + ccp.a = 7; + cc.writeA(); + cc.writeS(); // to prove I'm not making things up + // Interfaces work same as in D, basically. Or Java. + interface E { void doE(); } + // Inheritance works same as in D, basically. Or Java. + class D : C, E { + override void writeA() { writeln "hahahahaha no"; } + override void doE() { writeln "eeeee"; } + // all classes inherit from Object. (toString is defined in Object) + override string toString() { return "I am a D"; } + } + C cd = new D; + // all methods are always virtual. + cd.writeA(); + E e = E:cd; // dynamic class cast! + e.doE(); + writeln "$e"; // all interfaces convert to Object implicitly. + + // Templates! + // Templates are parameterized namespaces, taking a type as a parameter. + template Templ(T) { + alias hi = 5, hii = 8; + // Templates always have to include something with the same name as the template + // - this will become the template's _value_. + // Static ifs are evaluated statically, at compile-time. + // Because of this, the test has to be a constant expression, + // or something that can be optimized to a constant. + static if (types-equal (T, int)) { + alias Templ = hi; + } else { + alias Templ = hii; + } + } + assert(Templ!int == 5); + assert(Templ!float == 8); +} +``` + +## Topics Not Covered + + * Extended iterator types and expressions + * Standard library + * Conditions (error handling) + * Macros |