LIL Presentation

LIL Presentation

• 1.
  The LIL Language Whatis LIL
• 2.
  What is LIL LIL is a small programming language  LIL stands for Little Interpreted Language  Focused on being an extension language  Highly dynamic  Minimal syntax  Easy to embed
• 3.
  LIL is small A small core set of functions (about 50)  String handling  Lists  Flow control  etc  A pair of .c and .h files  About 3000 lines of C source code  Could be smaller, but had to be usable :-)  The ”lil” executable is ~40K (Linux x86)
• 4.
  Extension languages  Alanguage to write extensions for a host program  Extensions depend on the program but most complex programs can be extended via scripts  A wizard for an office application  The logic for a game character  Responses for web requests in a server  A text editor script to convert a set of ”#define” lines to ”case” lines for C code which return a string with the constant's name without some prefix  I need this more often than i would want...
• 5.
  LIL is anextension language  A host can extend the language by providing new functions  in LIL everything is done via functions, including control structures like if, for, while, etc  a function can execute code passed as a function argument, set a new local or global variable, create new execution environments, etc  Listen to callbacks for I/O, errors, exit requests, writing and reading to variables, etc  I/O callbacks can be used to sandbox script  Variable callbacks can expose host variables
• 6.
  LIL is highlydynamic  No separate compilation and execution step  The runtime can be modified at any time  New variables can be introduced  New functions can be defined – or redefined  Functions can be renamed – including natives  The runtime can be inspected via reflection  All code and data is stored as strings and converted to the appropriate type when needed  Code can be generated and is evaluated lazyly  String functions can be used with, e.g. lists
• 7.
  LIL has minimalsyntax  Everything follows a simple format: word1 word2 word3 … wordn  For commands the first word is the function name and the rest are the function arguments  Words are separated by space, but they can contain special characters and/or be inside special quotes (single quotes, double quotes, braces and brackets)  Words can contain spaces or other special characters, including – if escaped properly – characters with a special meaning for LIL
• 8.
  LIL has minimalsyntax (cont.)  Single and double quotes can be used to include spaces and/or escaping characters  A command inside [ and ] is executed and its result is used in place of the […]  Anything inside { and } is used as-is  however LIL will count the {s and }s so that they can be nested  $ followed by a word evalutes to a variable read  this can be changed at runtime to do other things  And that is it. See LIL's readme.txt for details
• 9.
  LIL is easyto embed  Uses a readable and permissive license: zlib  Written in C89 with few common C99 features  Can be used as a shared or static library  or just drop the lil.c and lil.h pair in your project  Small API to learn with few simple calls needed for practical use  Can be used with C and C++ directly and from languages which support C shared libraries  Import LIL is a project that provides bindings for Free Pascal and .NET (and others in the future)
• 10.
  Some examples LIL languageexamples
• 11.
  LIL examples  Mandatoryhello world print Hello, world  Notice how quotes are not needed  Error-try-catch try { if stuff { error ”Bad stuff” } } { print  Got an error: [reflect error] }  Factorial of 10 print [[func {x} { if [expr $x == 1] { return 1  } { return [expr [[reflect name] [expr $x ­ 1]]  * $x] }}] 10]
• 12.
  LIL examples (cont.) # print all known functions with name lengths # less than five characters set known­funcs [reflect funcs] set predicate {[length $x] < 5} set small­funcs [filter $known­funcs $predicate] print "Functions with small names:" foreach $small­funcs {print "  $i"}
• 13.
  C API examples Create and destroy a LIL runtime lil_t lil = lil_new(); /* do stuff here */ lil_free(lil);  Run some LIL code lil_free_value(lil_parse(lil,”print hi”,0,0));  Register a custom function lil_register(lil, ”newfunc”, fnc_newfunc);  fnc_newfunc is defined in the next slide
• 14.
  C API examples(cont.) /* myfunc native function */ LILCALLBACK lil_value_t fnc_myfunc(     lil_t lil,         /* lil runtime */     size_t argc,       /* number of arguments */     lil_value_t* argv) /* arguments array */ {     size_t i;     printf(”I've got %i arguments:”, (int)argc);     for (i=0; i<argc; i++)         printf(”  '%s'n”,             lil_to_string(argv[i]));     return lil_alloc_string(”myfunc result!”); }
• 15.
  print ”That wasit” That was it
• 16.
  More information  LILat github: https://github.com/badsector/lil  Latest source code  Wiki  Issue db  The readme.txt file in LIL's source code  Everything about LIL  Syntax  Reference  Import LIL: https://github.com/badsector/implil  Bindings for Free Pascal, .NET and maybe others