diff --git a/src/append.rs b/src/append.rs
new file mode 100644
index 0000000..7a6c01d
--- /dev/null
+++ b/src/append.rs
@@ -0,0 +1,68 @@
+/* relish: versatile lisp shell
+ * Copyright (C) 2021 Aidan Hahn
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+use crate::func::{FTable, Function, Args, Operation};
+use crate::vars::{VTable};
+use crate::segment::{Ctr, Ast, circuit, list_idx, list_append, new_ast};
+use std::rc::Rc;
+use std::cell::RefCell;
+
+pub fn get_append() -> Function {
+    return Function{
+        name: String::from("append"),
+        loose_syms: false,
+        eval_lazy: false,
+        args: Args::Lazy(-1),
+        function: Operation::Internal(
+            |a: Ast, _b: Rc<RefCell<VTable>>, _c: Rc<RefCell<FTable>>| -> Ctr {
+                let ptr = list_idx(a.clone(), 0);
+                match ptr {
+                    Ctr::Seg(ref c) => {
+                        let acpy = a.clone();
+                        match acpy.borrow().cdr.clone() {
+                            Ctr::Seg(cn) => {
+                                // append to list case
+                                if !circuit(cn, &mut |arg: &Ctr| -> bool {
+                                    list_append(c.clone(), arg.clone());
+                                    return true;
+                                }) {
+                                    eprintln!("get_append circuit loop should not have returned false");
+                                }
+                            },
+                            _ => {
+                                eprintln!("get_append args somehow not in standard form");
+                            }
+                        }
+
+                        return ptr;
+                    },
+                    _ => {
+                        let n = new_ast(Ctr::None, Ctr::None);
+                        if !circuit(a, &mut |arg: &Ctr| -> bool {
+                            list_append(n.clone(), arg.clone());
+                            return true;
+                        }) {
+                            eprintln!("get_append circuit loop should not have returned false");
+                        }
+
+                        return Ctr::Seg(n);
+                    }
+                }
+            }
+        )
+    };
+}
diff --git a/src/bin/main.rs b/src/bin/main.rs
index cea578f..1b180c1 100644
--- a/src/bin/main.rs
+++ b/src/bin/main.rs
@@ -98,7 +98,7 @@ fn main() {
                 return
             },
             Err(err) => {
-                println!("Prompt error: {:?}", err);
+                eprintln!("Prompt error: {:?}", err);
                 break
             }
         }
diff --git a/src/lib.rs b/src/lib.rs
index c441a1e..23bac7b 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -22,6 +22,7 @@ mod eval;
 mod vars;
 mod stl;
 mod str;
+mod append;
 
 pub mod ast {
     pub use crate::segment::{Seg, Ctr, ast_to_string, Type, Ast, new_ast};
@@ -36,4 +37,5 @@ pub mod ast {
 pub mod stdlib {
     pub use crate::stl::{get_stdlib};
     pub use crate::str::{get_echo};
+    pub use crate::append::{get_append};
 }
diff --git a/src/stl.rs b/src/stl.rs
index 0ffeed6..6a4690b 100644
--- a/src/stl.rs
+++ b/src/stl.rs
@@ -14,7 +14,9 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
+
 use crate::str::get_echo;
+use crate::append::get_append;
 use crate::func::{FTable, func_declare};
 use std::rc::Rc;
 use std::cell::RefCell;
@@ -24,6 +26,9 @@ pub fn get_stdlib() -> Result<Rc<RefCell<FTable>>, String> {
     if let Some(s) = func_declare(ft.clone(), Rc::new(RefCell::new(get_echo()))) {
         return Err(s)
     }
+    if let Some(s) = func_declare(ft.clone(), Rc::new(RefCell::new(get_append()))) {
+        return Err(s)
+    }
 
     return Ok(ft)
 }
diff --git a/src/str.rs b/src/str.rs
index 6384ad3..d0dfe6f 100644
--- a/src/str.rs
+++ b/src/str.rs
@@ -21,6 +21,8 @@ use crate::segment::{Ctr, Ast, circuit, ast_as_string};
 use std::rc::Rc;
 use std::cell::RefCell;
 
+// Current primitive is to use a get_NNNNN function defined for each library function which returns a not-previously-owned
+// copy of the Function struct.
 pub fn get_echo() -> Function {
     return Function{
         name: String::from("echo"),
@@ -44,8 +46,7 @@ pub fn get_echo() -> Function {
                     string.push_str("\n");
                     return true;
                 }) {
-                    // TODO: use custom logger
-                    println!("Echo failure!")
+                    eprintln!("circuit loop in echo should not have returned false")
                 }
                 return Ctr::String(string);
             }