added destructuring assignments for tuples (and lists on the left)

examples/destructuring_assignment.mers

@@ -0,0 +1,12 @@
+x := "https:\//www.google.com"
+
+x.debug()
+
+[a, [b, c]] := [1, ["str", 12.5]]
+
+println("---")
+println(a.to_string() + " " + b + " " + c.to_string())
+println("~~~")
+
+// switch! run_command("curl", [x, ...]) {
+// }

mers/src/lang/code_runnable.rs

@@ -1,4 +1,7 @@
-use std::sync::{Arc, Mutex};
+use std::{
+    eprintln,
+    sync::{Arc, Mutex},
+};
 
 use super::{
     builtins::BuiltinFunction,
@@ -106,33 +109,45 @@ pub struct RStatement {
     pub force_output_type: Option<VType>,
 }
 impl RStatement {
+    fn assign_to(assign_from: VData, mut assign_to: VData, info: &GSInfo) {
+        eprintln!("Assigning: '{assign_from}'.");
+        assign_to.operate_on_data_mut(|assign_to| match assign_to {
+            VDataEnum::Tuple(v) | VDataEnum::List(_, v) => {
+                for (i, v) in v.iter().enumerate() {
+                    Self::assign_to(
+                        assign_from.get(i).expect(
+                            "tried to assign to tuple, but value didn't return Some(_) on get()",
+                        ),
+                        v.clone_data(),
+                        info,
+                    )
+                }
+            }
+            VDataEnum::Reference(r) => r.assign(assign_from),
+            o => todo!("ERR: Cannot assign to {o}."),
+        })
+    }
     pub fn run(&self, info: &GSInfo) -> VData {
         let out = self.statement.run(info);
         if let Some((v, derefs, is_init)) = &self.output_to {
             'init: {
-                // assigns a new VData to the variable's Arc<Mutex<_>>, so that threads which have captured the variable at some point
-                // won't be updated with its new value (is_init is set to true for initializations, such as in a loop - this can happen multiple times, but each should be its own variable with the same name)
-                if *is_init && *derefs == 0 {
-                    if let RStatementEnum::Variable(var, _, _) = v.statement.as_ref() {
-                        let mut varl = var.lock().unwrap();
-                        #[cfg(debug_assertions)]
-                        let varname = varl.1.clone();
-                        *varl = out;
-                        #[cfg(debug_assertions)]
-                        {
-                            varl.1 = varname;
-                        }
-                        break 'init;
-                    }
-                }
+                // // assigns a new VData to the variable's Arc<Mutex<_>>, so that threads which have captured the variable at some point
+                // // won't be updated with its new value (is_init is set to true for initializations, such as in a loop - this can happen multiple times, but each should be its own variable with the same name)
+                // if *is_init && *derefs == 0 {
+                //     Self::assign_to(out, v.run(info), info);
+                //     break 'init;
+                // }
                 let mut val = v.run(info);
+                if !*is_init {
                     for _ in 0..(*derefs + 1) {
                         val = match val.deref() {
                             Some(v) => v,
                             None => unreachable!("can't dereference..."),
                         };
                     }
-                val.assign(out);
+                }
+                Self::assign_to(out, val, info);
+                // val.assign(out);
             }
             VDataEnum::Tuple(vec![]).to()
         } else {

mers/src/lang/to_runnable.rs

@@ -1,3 +1,4 @@
+use core::panic;
 use std::{
     collections::HashMap,
     fmt::{Debug, Display},
@@ -347,21 +348,39 @@ fn statement(
     ginfo: &mut GlobalScriptInfo,
     linfo: &mut LInfo,
 ) -> Result<RStatement, ToRunnableError> {
-    statement_adv(s, ginfo, linfo, None)
+    statement_adv(s, ginfo, linfo, &mut None)
 }
 fn statement_adv(
     s: &SStatement,
     ginfo: &mut GlobalScriptInfo,
     linfo: &mut LInfo,
     // if Some((t, is_init)), the statement creates by this function is the left side of an assignment, meaning it can create variables. t is the type that will be assigned to it.
-    to_be_assigned_to: Option<(VType, &mut bool)>,
+    to_be_assigned_to: &mut Option<(VType, &mut bool)>,
 ) -> Result<RStatement, ToRunnableError> {
+    // eprintln!("TR : {}", s);
+    // if let Some(t) = &to_be_assigned_to {
+    //     eprintln!(" --> {}", t.0);
+    // }
     let mut state = match &*s.statement {
             SStatementEnum::Value(v) => RStatementEnum::Value(v.clone()),
             SStatementEnum::Tuple(v) | SStatementEnum::List(v) => {
                 let mut w = Vec::with_capacity(v.len());
-                for v in v {
-                    w.push(statement(v, ginfo, linfo)?);
+                let mut prev = None;
+                for (i, v) in v.iter().enumerate() {
+                    if let Some(t) = to_be_assigned_to {
+                        let out_t = if let Some(p) = &prev { p } else { &t.0 };
+                        let inner_t = if let Some(v) = out_t.get_always(i, ginfo) { v } else {
+                            panic!("cannot assign: cannot get_always({i}) on type {}.", out_t);
+                        };
+                        let p = std::mem::replace(&mut t.0, inner_t);
+                        if prev.is_none() {
+                            prev = Some(p);
+                        }
+                    };
+                    w.push(statement_adv(v, ginfo, linfo, to_be_assigned_to)?);
+                }
+                if let (Some(t), Some(prev)) = (to_be_assigned_to, prev) {
+                    t.0 = prev;
                 }
                 if let SStatementEnum::List(_) = &*s.statement {
                     RStatementEnum::List(w)
@@ -376,7 +395,7 @@ fn statement_adv(
                 if is_init_force || (existing_var.is_none() && ginfo.to_runnable_automatic_initialization) {
                     // if to_be_assigned_to is some (-> this is on the left side of an assignment), create a new variable. else, return an error.
                     if let Some((t, is_init)) = to_be_assigned_to {
-                        *is_init = true;
+                        **is_init = true;
                         #[cfg(not(debug_assertions))]
                         let var = VData::new_placeholder();
                         #[cfg(debug_assertions)]
@@ -385,7 +404,7 @@ fn statement_adv(
                         linfo.vars.insert(v.to_owned(), (Arc::clone(&var_arc), t.clone()));
                         RStatementEnum::Variable(
                             var_arc,
-                            t,
+                            t.clone(),
                             true,
                         )
                     } else {
@@ -686,12 +705,13 @@ fn statement_adv(
             opt,
             ginfo,
             linfo,
-            if *derefs == 0 {
+            &mut if *derefs == 0 {
                 Some((state.out(ginfo), &mut is_init))
             } else {
                 None
             },
         )?;
+        if !is_init {
             let mut opt_type = optr.out(ginfo);
             for _ in 0..*derefs {
                 if let Some(deref_type) = optr.out(ginfo).dereference() {
@@ -722,6 +742,10 @@ fn statement_adv(
                     opt_type_assign,
                 ));
             }
+        } else {
+            // TODO! ??
+            state.output_to = Some((Box::new(optr), *derefs, is_init));
+        }
         //
         // if let Some((var_id, var_out)) = linfo.vars.get(opt) {
         //     let out = state.out(ginfo);

mers/src/lang/val_type.rs

@@ -34,7 +34,7 @@ pub enum VSingleType {
 }
 
 impl VSingleType {
-    // None => Cannot get, Some(t) => getting can return t or nothing
+    /// None => Cannot get, Some(t) => getting can return t or nothing
     pub fn get(&self, i: usize, gsinfo: &GlobalScriptInfo) -> Option<VType> {
         match self {
             Self::Bool | Self::Int | Self::Float | Self::Function(..) | Self::Thread(..) => None,
@@ -63,7 +63,7 @@ impl VSingleType {
             }
         }
     }
-    // None => might not always return t, Some(t) => can only return t
+    /// None => might not always return t, Some(t) => can only return t
     pub fn get_always(&self, i: usize, info: &GlobalScriptInfo) -> Option<VType> {
         match self {
             Self::Bool