Syntax

program :=
     <function \n>+ (NOTE: angular braces are used for grouping)

function :=
     type ident() stmtblock
     type ident(type ident <, type ident>*) stmtblock

type :=
  bool
  int
  array
  void

stmtblock :=
     {\n <stmt \n>* }

stmt :=
     stmtblock
     type ident <, ident>*
     array ident\[expr\] <, ident\[expr\]>*
     print(<string|expr> <, <string|expr> >*
     if (expr) stmtblock [else stmtblock]
     while (expr) stmtblock
     for (ident : expr) stmtblock
     ident := expr
     ident\[expr\] := expr
     expr
     ;[^\n]*
     return [expr]
     abort(<string|expr> <, <string|expr> >*

expr :=
     true
     false
     -?[0-9]+
     ident
     (expr ? expr : expr)
     sizeof(ident)
     input()
     ident\[expr\]
     ident()
     ident(expr <, expr>*)
     (expr binop expr)
     (unaryop expr)

binop :=
     + - * ^ / % & | == != > >= < <=
    (caret is exponentiation, we have no xor operator)

unaryop :=
    - !
    (bang is Boolean not)

string :=
    " ('\\' ["nt\\] | [^\\\n"])*  "

ident :=
     [a-zA-Z_][a-zA-Z0-9_]*

Features

• All variables are initialized to 0 by default, including array elements.
• Any attempt to access or assign an array element out of bounds traps.

Building

Create a buid directory for yourself and do:

cmake .. (assuming you created builddir in the root directory)

make

It will create binary called lilang. You can check for various options with lilang --help

Files that should be parsed by this compiler are in passing-tests/ and files that should not be parsed are in failing-tests/ directory.

You can do:

ctest to run the tests.

Compiling and executing .lil files

Use the compiler driver (called little) that calls the frontend (called lilang) automatically and creates an executable a.out in the current directory.

Eg:

./little lil.lil

The above compiler driver basically does following:

Say you have a file, lil.lil. It compiles to LLVM IR like follows:

./lilang lil.lil --print-ir=a.bc

The file a.bc now contains the LLVM IR in textual form. If you want to execute it, you need to link it with the runtime file as follows:

clang runtime.c a.bc -o file.out