added env function and test

src/stl/decl.rs

@@ -189,3 +189,24 @@ pub fn isset_callback(ast: &Seg, syms: &mut SymTable) -> Result<Ctr, String> {
         }
     }
 }
+
+pub const ENV_DOCSTRING: &str = "takes no arguments
+prints out all available symbols and their associated values";
+
+pub fn env_callback(_ast: &Seg, syms: &mut SymTable) -> Result<Ctr, String> {
+    let mut functions = vec![];
+    println!("VARIABLES:");
+    for (name, val) in syms.iter() {
+        match val.value {
+            ValueType::VarForm(_) => {
+                println!("  {}: {}", &name, val.value);
+            },
+            _ => functions.push(name.clone()),
+        }
+    }
+    println!("FUNCTIONS:");
+    for func in functions {
+        println!("  {}", func);
+    }
+    Ok(Ctr::None)
+}