usability improvements to env and def

* env prints variables and functions in seperate columns
* run/stl seperation of concerns significantly better
* def doesnt store lists or lambdas in the environment

src/bin/relish.rs

@@ -19,11 +19,13 @@ use {
     relish::{
         ast::{
             eval, lex, run,
-            Ctr, Seg, SymTable,
-            load_defaults, load_environment
+            Ctr, Seg, SymTable, Symbol,
         },
         stdlib::{
-            static_stdlib, dynamic_stdlib
+            static_stdlib, dynamic_stdlib, load_defaults,
+            load_environment,
+            CONSOLE_XDIM_VNAME, CONSOLE_YDIM_VNAME, CFG_FILE_VNAME,
+            L_PROMPT_VNAME, R_PROMPT_VNAME, PROMPT_DELIM_VNAME,
         },
         aux::{ShellState, check_jobs},
     },
@@ -46,6 +48,7 @@ use {
     nix::unistd,
     nu_ansi_term::{Color, Style},
     dirs::home_dir,
+    termion::terminal_size,
 };
 
 #[derive(Clone)]
@@ -252,7 +255,7 @@ fn main() {
     // this is a user shell. attempt to load configuration
     {
         // scope the below borrow of syms
-        let cfg_file = env::var("RELISH_CFG_FILE").unwrap_or(cfg_file_name);
+        let cfg_file = env::var(CFG_FILE_VNAME).unwrap_or(cfg_file_name);
         run(cfg_file.clone(), &mut syms)
             .unwrap_or_else(|err: String| eprintln!("failed to load script {}\n{}", cfg_file, err));
     }
@@ -284,8 +287,11 @@ fn main() {
             .with_style(Style::new().italic().fg(Color::LightGray)),
     )).with_validator(Box::new(DefaultValidator));
 
+    let mut xdimension: u16 = 0;
+    let mut ydimension: u16 = 0;
     loop {
         {
+            // update state
             check_jobs(&mut prompt_ss.borrow_mut());
         }
         let readline_prompt = make_prompt(&mut syms);
@@ -293,6 +299,11 @@ fn main() {
         // realloc with each loop because syms can change
         rl = rl.with_completer(Box::new(completer));
         let user_doc = rl.read_line(&readline_prompt).unwrap();
+
+        // doing this update here prevents needing to update twice before dimensions take effect
+        (xdimension, ydimension) =
+            check_and_update_console_dimensions(&mut syms, xdimension, ydimension);
+
         match user_doc {
             Signal::Success(line) => {
                 println!(""); // add a new line before output gets printed
@@ -320,19 +331,19 @@ fn main() {
 
 fn make_prompt(syms: &mut SymTable) -> CustomPrompt {
     let l_ctr = *syms
-        .call_symbol(&"CFG_RELISH_L_PROMPT".to_string(), &Seg::new(), true)
+        .call_symbol(&L_PROMPT_VNAME.to_string(), &Seg::new(), true)
         .unwrap_or_else(|err: String| {
             eprintln!("{}", err);
             Box::new(Ctr::String("<prompt broken!>".to_string()))
         });
     let r_ctr = *syms
-        .call_symbol(&"CFG_RELISH_R_PROMPT".to_string(), &Seg::new(), true)
+        .call_symbol(&R_PROMPT_VNAME.to_string(), &Seg::new(), true)
         .unwrap_or_else(|err: String| {
             eprintln!("{}", err);
             Box::new(Ctr::String("<prompt broken!>".to_string()))
         });
     let d_ctr = *syms
-        .call_symbol(&"CFG_RELISH_PROMPT_DELIMITER".to_string(), &Seg::new(), true)
+        .call_symbol(&PROMPT_DELIM_VNAME.to_string(), &Seg::new(), true)
         .unwrap_or_else(|err: String| {
             eprintln!("{}", err);
             Box::new(Ctr::String("<prompt broken!>".to_string()))
@@ -397,3 +408,47 @@ fn get_token_to_complete(line: &str, pos: usize) -> (String, bool, usize) {
 
     return (res, is_str, start_idx)
 }
+
+/* It was considered that a SIGWINCH handler would be a more
+ * elegant solution to this. Such a solution would need to
+ * modify the current libc based approach to use a state-enclosing
+ * closure as a signal handler. As of May 2023 there is no clear
+ * way of doing such a thing.
+ *
+ * Luckily this data is only used within Relish, so we can simply
+ * rely on it only being read during the evaluation phase of the REPL.
+ * This method will at least work for that. (ava)
+ */
+fn check_and_update_console_dimensions(
+    syms: &mut SymTable,
+    last_xdim: u16,
+    last_ydim: u16
+) -> (u16, u16) {
+    let (xdim, ydim) = terminal_size().expect("Couldnt get console dimensions");
+
+    if xdim != last_xdim {
+        syms.insert(
+            String::from(CONSOLE_XDIM_VNAME),
+            Symbol::from_ast(
+                &String::from(CONSOLE_XDIM_VNAME),
+                &String::from("Length of current console"),
+                &Seg::from_mono(Box::new(Ctr::Integer(xdim.into()))),
+                None,
+            )
+        );
+    }
+
+    if ydim != last_ydim {
+        syms.insert(
+            String::from(CONSOLE_YDIM_VNAME),
+            Symbol::from_ast(
+                &String::from(CONSOLE_YDIM_VNAME),
+                &String::from("Height of current console"),
+                &Seg::from_mono(Box::new(Ctr::Integer(ydim.into()))),
+                None,
+            )
+        );
+    }
+
+    (xdim, ydim)
+}