making this work as a library

Cargo.toml

@@ -3,6 +3,10 @@ name = "crisp"
 version = "0.1.0"
 edition = "2021"
 
+[lib]
+crate-type = ["staticlib"]
+path = "src/lib.rs"
+
 [dependencies]
 color-eyre = "0.6.3"
 lazy_static = "1.5.0"

src/env.rs

@@ -24,7 +24,11 @@ impl Environment {
         if let Some(value) = self.symbols.get(symbol) {
             value
         } else {
-            &Value::Nil
+            if let Some(env) = &*self.outer {
+                env.get_symbol(symbol)
+            } else {
+                &Value::Nil
+            }
         }
     }
 }

src/lib.rs

@@ -0,0 +1,138 @@
+use std::collections::HashMap;
+
+use color_eyre::{
+    eyre::{eyre, ContextCompat},
+    Result,
+};
+use env::Environment;
+use printer::print;
+use reader::read;
+use regex::Regex;
+use rustyline::{config::Configurer, error::ReadlineError, Editor};
+
+pub mod env;
+pub mod macros;
+pub mod printer;
+pub mod reader;
+pub mod types;
+use types::*;
+
+pub fn main() -> Result<()> {
+    let mut rl = Editor::<(), rustyline::history::DefaultHistory>::new().unwrap();
+    if rl.load_history(".mal-history").is_err() {
+        eprintln!("No previous history.");
+    }
+    rl.set_edit_mode(rustyline::EditMode::Vi);
+
+    let mut env = Environment::new();
+    env.insert_symbol(
+        Symbol::from("+"),
+        Value::func(|args| {
+            let nums: Vec<i64> = args
+                .iter()
+                .map(|a| match a {
+                    Value::Number(a) => Ok(*a),
+                    _ => Err(eyre!("Should be a number")),
+                })
+                .flatten()
+                .collect();
+            let total = nums
+                .into_iter()
+                .reduce(|acc, e| acc + e)
+                .expect("shouldn't fail");
+            Ok(Value::from(total))
+        }),
+    );
+    env.insert_symbol(
+        Symbol::from("-"),
+        Value::func(|args| {
+            let nums: Vec<i64> = args
+                .iter()
+                .map(|a| match a {
+                    Value::Number(a) => Ok(*a),
+                    _ => Err(eyre!("Should be a number")),
+                })
+                .flatten()
+                .collect();
+            let total = nums
+                .into_iter()
+                .reduce(|acc, n| acc - n)
+                .expect("shouldn't fail");
+            Ok(Value::from(total))
+        }),
+    );
+
+    loop {
+        let entry = rl.readline(">> ");
+        match entry {
+            Ok(line) => {
+                rl.add_history_entry(line.as_str())?;
+                match read_eval_print(line.as_str(), &mut env) {
+                    Ok(s) => println!("{s}"),
+                    Err(e) => eprintln!("{e}"),
+                }
+            }
+            Err(ReadlineError::Interrupted) => {
+                println!("CTRL-C");
+                break;
+            }
+            Err(ReadlineError::Eof) => {
+                println!("CTRL-D");
+                break;
+            }
+            Err(err) => {
+                println!("Error: {:?}", err);
+                break;
+            }
+        }
+    }
+    Ok(())
+}
+
+pub fn read_eval_print(str: &str, env: &mut Environment) -> Result<String> {
+    Ok(print(&eval(&read(str), env)?))
+}
+
+pub fn eval(expr: &Value, env: &mut Environment) -> Result<Value> {
+    match expr {
+        Value::Symbol(s) => {
+            let symbol = env.get_symbol(s).to_owned();
+            Ok(symbol)
+        }
+        Value::List(list) => {
+            let mut args = vec![];
+            let first = &list[0];
+            if let Value::List(_) = first {
+                eval(first, env)
+            } else if let Value::Symbol(s) = first {
+                if s == &Symbol("defvar".to_string()) {
+                    let second = &list[1];
+                    if let Value::Symbol(s) = second {
+                        Ok(Value::Symbol(s.clone()))
+                    } else {
+                        todo!()
+                    }
+                } else if s == &Symbol("let*".to_string()) {
+                    todo!()
+                } else {
+                    let first = eval(first, env)?;
+                    for value in list.iter().skip(1) {
+                        if let Ok(return_value) = eval(value, env) {
+                            args.push(return_value)
+                        }
+                    }
+                    first.apply(args)
+                }
+            } else {
+                let first = eval(first, env)?;
+                for value in list.iter().skip(1) {
+                    if let Ok(return_value) = eval(value, env) {
+                        args.push(return_value)
+                    }
+                }
+                first.apply(args)
+            }
+        }
+        value => Ok(value.to_owned()),
+    }
+}

src/main.rs

@@ -104,6 +104,19 @@ fn eval(expr: &Value, env: &Environment) -> Result<Value> {
             let first = &list[0];
             if let Value::List(_) = first {
                 eval(first, env)
+            } else if let Value::Symbol(s) = first {
+                if s == &Symbol("defvar".to_string()) {
+                    let second = &list[1];
+                    if let Value::Symbol(s) = second {
+                        Ok(Value::Symbol(s.clone()))
+                    } else {
+                        todo!()
+                    }
+                } else if s == &Symbol("let*".to_string()) {
+                    todo!()
+                } else {
+                    todo!()
+                }
             } else {
                 let first = eval(first, env)?;
                 for value in list.iter().skip(1) {