start to document syntax

README.md

@@ -42,4 +42,166 @@ You can compile this to `technotunnel.wasm` with the command
 curlywas technotunnel.cwa
 ```
 
-Then run it on [MicroW8](https://exoticorn.github.io/microw8/v0.1pre2)
+Then run it on [MicroW8](https://exoticorn.github.io/microw8/v0.1pre2)
+
+## Syntax
+
+### Comments
+
+```
+// This is a single line comment.
+
+/*
+   Multiline comments are also supported.
+*/
+```
+
+### Types
+
+There are four types in WebAssembly and therefore Curlywas:
+
+* `i32`: 32bit integer
+* `i64`: 64bit integer
+* `f32`: 32bit float
+* `f64`: 64bit float
+
+There are no unsigned types, but there are unsigned operators where it makes a difference.
+
+### Literals
+
+Integer numbers can be given either in decimal or hex:
+
+```
+123, -7878, 0xf00
+```
+
+For floating point numbers, only the most basic decimal format is currently implemented (no scientific notation or hex-floats, yet):
+
+```
+0.464, 3.141, -10.0
+```
+
+String literals exist in a very basic form. No escape character implemented yet.
+
+```
+"env.memory", "Hello World!"
+
+this does not work, yet:
+
+"one line\nsecond line", "They said: \"Enough!\""
+```
+
+### Imports
+
+WebAssembly imports are specified with a module and a name. In Curlywas you give them inside a single string literal, seperated by a dot. So a module `env` and name `printString` would be written `"env.printString"`.
+
+Linear memory can be imported like this:
+
+```
+import "module.name" memory(min_pages);
+```
+
+giving the minimum required size as the number of 64KB pages.
+
+Global variables can be imported with:
+
+```
+import "module.name" global var_name: type;     // const global
+import "module.name" global mut var_name: type; // mutable global
+```
+
+`var_name` being the name you want to reference the variable by in your code.
+
+Functions are imported like this:
+
+```
+import "module.name" fn fun_name(param_types) [-> return_type];
+
+examples:
+
+import "env.cls" cls(i32);         // no return type
+import "env.random" rand() -> i32; // no params
+import "env.atan2" atan2(f32, f32) -> f32;
+```
+
+### Functions
+
+Functions look like this:
+
+```
+[export] fn name(param_list) [-> return_type] {
+    [...]
+}
+
+exampels:
+
+fn getPixel(x: i32, y: i32) -> i32 {
+    ...
+}
+
+export fn upd() {
+    ...
+}
+```
+
+#### Local variables
+
+Variables are defined using `let`:
+
+```
+let name: type;
+```
+
+They can also be initialized to a value at the same time, in this case the type can be left out and will be infered:
+
+```
+let name = expression;
+```
+
+There are two modifiers that change when the initializer expression is actually evaluated.
+
+They both can reduce the size of the resulting code, but it is up to the coder to make sure that the delayed evaluation doesn't change the semantics of the code.
+
+```
+let inline name = expression;
+```
+
+The expression is evaluated (inlined) everytime you use the variable.
+
+```
+let lazy name = expression;
+```
+
+The expression is evaluated and assigned to the variable at the first place it is used (and only there).
+
+`let lazy` uses the `local.tee` instruction which combines `local.set` and `local.get` and therefore saves on instruction (usually 2 bytes).
+
+Examples of mistakes to watch out for:
+```
+let x = 4;
+let inline y = 7;
+print(y); // prints 11
+x = x + 2;
+print(y); // prints 13
+```
+
+```
+let inline num_bytes = write(buffer, size);
+print(num_bytes);
+read(buffer, num_bytes); // calls write a second time
+```
+
+```
+let lazy num_bytes = write(header, 8);
+write(body, size);
+print(num_bytes); // the header is only written now
+```
+
+```
+let lazy foo = 42;
+if rand() & 1 {
+    printNumber(foo); // foo is initialized here
+} else {
+    printNumber(foo / 2 + 2); // foo is never initialized in the else branch
+}
+```