Add examples to readme

README.md

@@ -1,62 +1,49 @@
 # Saft
 
-Saft is my custom programming language.
+Saft is my custom programming language. The syntax has a high resemblence to
+rust and some concepts have carried over, such as block expressions and control
+flow expressions, and tail expressions being returned automatically.
 
-## Syntax
+## State of the language
 
-The syntax in Saft is very inspired by rust, but instead using the `:=` operator for declarations instead of the `let` keyword.
-Since Saft is not yet typed all types are omitted from declarations, parameters and return values.
+Currently saft has a lexer, parser, ir (with lowerer) and a bytecode back-end,
+which both compiles and interprets bytecode. I have added type annotations, but
+type inference and checking has not been implemented yet, so types do nothing
+at the moment.
 
-### EBNF
+## Examples
 
-```
-program = { statement }
-
-statement = item
-          | stmt , ';'
-
-item = fn
-
-fn = 'fn' , '(', [ Ident , {',' , Ident } ] ')' block
-
-stmt = 'return' , expr
-     | declaration
-     | expr
+Below is an example of the fibonacci function, implemented recursively.
 
+```
+fn fib(i: int) -> int {
+    if i < 2 {
+        i
+    } else {
+        fib(i-1) + fib(i-2)
+    }
+}
+```
 
-declaration = Ident , ':=' , expr
-
-block = '{' , { statement } , [ expr ] '}'
+Here is the fibonacci function implemented with a loop.
 
-expr = p_none
+```
+fn fib(n: int) -> int {
+    if n == 0 { return 0; };
 
-p_none = p_assign
-p_assign = p_or | p_assign , '=' , p_or
-p_or = p_and | p_or , 'or' , p_and
-p_and = p_eq | p_and , 'and' , p_eq
-p_eq = p_cmp | p_eq , ( '==' | '!=' ) , p_cmp
-p_cmp = p_term | p_cmp , ( '<' | '<=' | '>' | '>=' ) , p_term
-p_term = p_fac | p_term , ('+' | '-' ) , p_fac
-p_fac = p_unary | p_fac ( '*' | '-' ) , p_unary
-p_unary = p_exp | ( '-' | '!' ) , p_unary
-p_exp = p_call | p_call , '^' , p_exp
-p_call = p_primary | p_call , '(' [ expr { ',' expr } ] ')'
-p_primary = primary_expr
+    let a = 0;
+    let b = 1;
 
-primary_expr = Ident
-     | Float
-     | Integer
-     | 'nil'
-     | 'true'
-     | 'false'
-     | String
-     | list
-     | '(' , expr , ')'
-     | 'break' , expr
-     | 'loop' , expr , block
-     | if
+    loop {
+        if n == 1 {
+            break b;
+        };
 
-list = '[' [ expr { ',' , expr } ] ']'
+        let c = a + b;
+        a = b;
+        b = c;
 
-if = 'if' , expr , block , [ 'else' , ( block | if ) ]
+        n = n - 1;
+    }
+}
 ```