This crate provides a small and simple embeddable scripting language. Its syntax gravitates around functions and argument composition for functions. A core concept is that everything is callable. It could be viewed as LISP without parenthesis, or as a mixture of Perl, JavaScript and LISP/Scheme.
Here are some of its properties:
The embedding API and all internal operations rely on a data structure made of VVal nodes.
Here you can find the WLambda Language Reference.
```rust use wlambda::*;
match wlambda::compiler::eval("40 + 2") { Ok(v) => { println!("Output: {}", v.s()); }, Err(e) => { eprintln!("Error: {}", e); }, } ```
See further down below for more API usage examples!
Try out WLambda right away in the WASM WLambda Evaluator.
```wlambda !x = 10; # Variable definition
.x = 20; # Variable assignment ```
```wlambda !x = (1 + 2) * (8 - 4) / 2;
std:assert_eq x 6; ```
wlambda
$true {
std:displayln "It's true!";
} {
std:displayln "It's false!";
};
```wlambda !x = 10 / 2;
(x == 5) { std:displayln "x == 5"; }; ```
```wlambda !x = 10;
while { x > 0 } { std:displayln x;
(x == 5) {
break[];
};
.x = x - 1;
}; ```
```wlambda !x = 10;
!r = while { x > 0 } { std:displayln x;
(x == 5) {
# break is a function, first arg
# is the return value for `while`:
break 5;
};
.x = x - 1;
};
std:assert_eq r 5; ```
wlambda
range 1 10 1 {
std:displayln "> " _;
};
With named counting variable:
wlambda
range 1 10 1 {!(i) = @; # or just `!i = _`
std:displayln "> " i;
};
```wlambda !x = 10;
while $true { std:displayln x; .x = x - 1; (x == 0) break; }; ```
```wlambda !add = { _ + _1 }; # argument names _, _1, _2, ...
!result = add 2 3;
std:assert_eq result 5; ```
Different function call syntaxes:
```wlambda !add = {!(x, y) = @; # named variables, @ evals to list of all args x + y };
std:displayln[add[2, 3]]; # [] parenthesis calling syntax
std:displayln add[2, 3]; # less parenthesis
std:displayln (add 2 3); # explicit expression delimiting with ( ... )
std:displayln ~ add 2 3; # ~ means: evaluate rest as one expression
```
```wlambda
!test = \:retlabela {!(x) = @;
# an `if` is actually a call to another function, so we need to
# dynamically jump upwards the call stack to the given label:
(x > 10) {
return :ret_label_a x * 2;
};
};
std:assert_eq (test 11) 22; ```
```wlambda !v = $[1, 2, 3]; v.1 = 5;
std:assert_eq v.1 5;
std:asserteq (std:pop v) 3; std:asserteq (std:pop v) 5; std:assert_eq (std:pop v) 1; ```
```wlambda !m = ${ a = 10, c = 2 };
m.b = m.a + m.c;
std:assert_eq m.b 12; ```
```wlambda !name = "Mr. X";
std:asserteq name.4 "X"; # index a character std:asserteq (name 0 3) "Mr."; # substring
!stuff = "日本人"; std:assert_eq stuff.0 "日"; # Unicode support ```
```wlambda !人 = "jin";
std:assert_eq 人 "jin"; ```
```wlambda !MyClass = ${ new = { ${ _proto = $self, _data = ${ balance = 0, } } }, deposit = { $data.balance = $data.balance + _; }, };
!account1 = MyClass.new[];
account1.deposit 100; account1.deposit 50;
std:asserteq account1.data.balance 150; ```
```wlambda
!MyClass = { !self = ${ balance = 0, };
self.deposit = { self.balance = self.balance + _; };
$:self
};
!account1 = MyClass[];
account1.deposit 100; account1.deposit 50;
std:assert_eq account1.balance 150; ```
```txt
!@import std std; !@wlambda;
!@export print_ten = { std:displayln ~ str 10; }; ```
For import you do:
```txt !@import u util;
u:print_ten[] ```
Just a quick glance at the WLambda syntax and semantics.
More details for the syntax and the provided global functions can be found in the WLambda Language Reference.
```wlambda
!a = 10;
.a = 20;
!a_list = $[1, 2, 3, 4];
!a_map = ${a = 10, b = 20};
!a_func = { _ + _1 # Arguments are not named, they are put into _, _1, _2 };
afunc[2, 3]; # Function call afunc 2 3; # Equivalent function call
!dosomethingto = _ * 2;
if statement. Booleans can be called(a == 10) { # called if a == 10 } { # called if a != 10 };
!sum = $&0; # Defining a reference that can be assignment # from inside a function.
range calls the given function for each iteration_range 0 10 1 { # This is a regular function. .sum = $sum + _; # $* is a dereferencing operator # and .* starts a reference assignment };
range loop with break!breakvalue = range 0 10 1 { ( == 5) { break 22 }; };
!somefun = \:somefunlbl { # \:xxx defines a function label for returning !x = 10; .x = dosomethingto x; (x > 20) { return :somefun_lbl 20; # explicit argument for return returns from # the specified block. } .x = 20; x };
return implicitly jumps to the topmost $nul label_ to jump out some unnamed func:!somefun = { !(x) = @; (x == 20) \:{ return 30 } # returns from some_fun, not from the if-branch };
# There are special error values, that will make the program panic
# if they are not handled correctly at statement block level:
!some_erroring_func = {
return $error "An error happened!"
};
!value = some_erroring_func[];
# on_error calls the first argument if the second argument
# is an error value.
on_error {
# handle error here, eg. report, or make a new error value
!(err_value, line, col, file) = @;
std:displayln err_value;
} value;
!handle_err = { std:displayln _ };
# with the ~ operator, you can chain it nicely:
on_error {|| handle_err[_] } ~ some_erroring_func[];
# or without ~:
on_error {|| handle_err[_] } (some_erroring_func[]);
# or with |
some_erroring_func[] | on_error {|| handle_err[_] };
# _? transforms an error value, and returns it from the current
# function. optionally jumping outwards.
std:assert_eq (str ~ std:to_ref ~ {
_? ~ $e "ok"; # is with an error value the same as: `return $e "ok"`
}[]) "$&&$e[98,17:<wlambda::eval>(Err)] \"ok\"";
_? 10; # passes the value through
!reportmyerror = { std:displayln _ };
!someerroringfunc = { onerror { reportmyerror _; } block :outer { # do something... ( != 10) { return :outer $error "Something really failed" # same as, with the difference, that _? only returns # from :outer if it is an error value. _? :outer $error "Something really failed" } # do more ... } # cleanup ... };
!someobj = $&${}; someobj.dosomething = { # do something here with someobj captured (weakly) # from the upper lexical scope. }; someobj.dosomething[]; # Method call
!some_class = ${ new = { ${ _proto = $self, a = 10, } }, bang = { std:str:cat "bang!" _ ":" $self.a }, };
!o = someclass.new[]; !r = o.bang 22; std:asserteq r "bang!22:10"; ```
Currently there are many more examples in the test cases in compiler.rs.
Here is how you can quickly evaluate a piece of WLambda code:
rust
let s = "$[1,2,3]";
let r = wlambda::compiler::eval(&s).unwrap();
println!("Res: {}", r.s());
If you want to quickly add some of your own functions,
you can use the GlobalEnv add_func method:
```rust use wlambda::vval::{VVal, VValFun, Env};
let globalenv = wlambda::GlobalEnv::newdefault(); globalenv.borrowmut().addfunc( "mycrazy_add", |env: &mut Env, _argc: usize| { Ok(VVal::Int( env.arg(0).i() * 11 + env.arg(1).i() * 13 )) }, Some(2), Some(2));
let mut ctx = wlambda::compiler::EvalContext::new(global_env);
// Please note, you can also add functions later on, // but this time directly to the EvalContext:
ctx.setglobalvar( "mycrazymul", &VValFun::new_fun(|env: &mut Env, _argc: usize| { Ok(VVal::Int( (env.arg(0).i() + 11) * (env.arg(1).i() + 13))) }, Some(2), Some(2), false));
let resadd : VVal = ctx.eval("mycrazyadd 2 4").unwrap(); asserteq!(res_add.i(), 74);
let resmul : VVal = ctx.eval("mycrazymul 2 4").unwrap(); asserteq!(res_mul.i(), 221); ```
```rust use wlambda::*;
let mut ctx = EvalContext::new_default();
ctx.eval("!x = 10").unwrap();
ctx.setglobalvar("y", &VVal::Int(32));
let r = ctx.eval("x + y").unwrap();
assert_eq!(r.s(), "42"); ```
There are several things that can be added more or less easily to WLambda. But I am currently working on making the language more complete for real world use. So my current goals are:
This project is licensed under the GNU General Public License Version 3 or later.
I (WeirdConstructor) herby promise to release WLambda under MIT / Apache-2.0 license if you use it in an open source / free software game (licensed under MIT and/or Apache-2.0) written in Rust (and WLambda) with a playable beta release, non trivial amount of content and enough gameplay to keep me occupied for at least 2 hours. You may use WLambda for your release as if it was released under MIT and/or Apache-2.0. Proper attribution as required by MIT and/or Apache-2.0.
Picking a license for my code bothered me for a long time. I read many discussions about this topic. Read the license explanations. And discussed this matter with other developers.
First about why I write code for free at all:
Those are the reasons why I write code for free. Now the reasons why I publish the code, when I could as well keep it to myself:
Most of those reasons don't yet justify GPL. The main point of the GPL, as far as I understand: The GPL makes sure the software stays free software until eternity. That the user of the software always stays in control. That the users have at least the means to adapt the software to new platforms or use cases. Even if the original authors don't maintain the software anymore. It ultimately prevents "vendor lock in". I really dislike vendor lock in, especially as developer. Especially as developer I want and need to stay in control of the computers I use.
Another point is, that my work has a value. If I give away my work without any strings attached, I effectively work for free. Work for free for companies. I would compromise the price I can demand for my skill, workforce and time.
This makes two reasons for me to choose the GPL:
Please contact me if you need a different license and really want to use my code. As long as I am the only author, I can change the license. We might find an agreement.
Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in WLambda by you, shall be licensed as GPLv3 or later, without any additional terms or conditions.
WeirdConstructor on the Rust Discord.)