1 files changed, 139 insertions, 0 deletions

diff --git a/src/lisp/prelude.rs b/src/lisp/prelude.rs
new file mode 100644
index 0000000..ad94cd2
--- /dev/null
+++ b/src/lisp/prelude.rs
@@ -0,0 +1,139 @@
+use crate::{
+    lisp::{
+        error::{EvalError, LispError},
+        expr::LispExpr,
+        number::LispNumber,
+        Environment,
+    },
+    primitive,
+};
+
+use std::convert::TryInto;
+
+#[macro_export]
+macro_rules! primitive {
+    ($env:expr, $arity:expr, $name:expr, $closure:expr) => {
+        let val = crate::lisp::expr::LispExpr::PrimitiveFunc(crate::lisp::expr::PrimitiveFunc {
+            arity: $arity,
+            closure: $closure,
+        });
+        let _ = $env.insert($name.to_string(), val);
+    };
+}
+
+pub fn new_env() -> Environment {
+    let mut env = Environment::new();
+
+    primitive!(env, Some(2), "+", |args, _| {
+        let nums = args
+            .into_iter()
+            .map(|arg| arg.try_into())
+            .collect::<Result<Vec<&LispNumber>, LispError>>()?;
+        return Ok(LispExpr::Number(
+            nums.iter().fold(LispNumber::Integer(0), |acc, &x| acc + *x),
+        ));
+    });
+
+    primitive!(env, Some(2), "-", |args, _| {
+        let nums = args
+            .into_iter()
+            .map(|arg| arg.try_into())
+            .collect::<Result<Vec<&LispNumber>, LispError>>()?;
+        let mut acc = nums[0].clone();
+        for arg in nums.into_iter().skip(1) {
+            acc = acc - *arg;
+        }
+        Ok(LispExpr::Number(acc))
+    });
+
+    primitive!(env, Some(2), "*", |args, _| {
+        let nums = args
+            .into_iter()
+            .map(|arg| arg.try_into())
+            .collect::<Result<Vec<&LispNumber>, LispError>>()?;
+        return Ok(LispExpr::Number(
+            nums.iter().fold(LispNumber::Integer(1), |acc, &x| acc * *x),
+        ));
+    });
+
+    primitive!(env, Some(2), "/", |args, _| {
+        let nums = args
+            .into_iter()
+            .map(|arg| arg.try_into())
+            .collect::<Result<Vec<&LispNumber>, LispError>>()?;
+        let mut acc = nums[0].clone();
+        for arg in nums.into_iter().skip(1) {
+            acc = acc.div(*arg)?;
+        }
+        Ok(LispExpr::Number(acc))
+    });
+
+    primitive!(env, Some(0), "toggle-grid", |_, app| {
+        app.toggle_grid();
+        Ok(LispExpr::Unit)
+    });
+
+    primitive!(env, Some(3), "if", |args, _| {
+        match args {
+            [predicate, then, else_] => {
+                if matches!(predicate, LispExpr::BoolLit(false)) {
+                    Ok(else_.clone())
+                } else {
+                    Ok(then.clone())
+                }
+            }
+            _ => {
+                panic!("panicked at `if` expression")
+            }
+        }
+    });
+
+    primitive!(env, Some(2), "and", |args, _| {
+        if args
+            .iter()
+            .any(|arg| matches!(arg, LispExpr::BoolLit(false)))
+        {
+            Ok(LispExpr::BoolLit(false))
+        } else {
+            Ok(LispExpr::BoolLit(true))
+        }
+    });
+
+    primitive!(env, Some(2), "or", |args, _| {
+        if args
+            .iter()
+            .any(|arg| matches!(arg, LispExpr::BoolLit(true)))
+        {
+            Ok(LispExpr::BoolLit(true))
+        } else {
+            Ok(LispExpr::BoolLit(false))
+        }
+    });
+
+    primitive!(env, Some(1), "not", |args, _| {
+        match args {
+            [val] => {
+                if matches!(val, LispExpr::BoolLit(false)) {
+                    Ok(LispExpr::BoolLit(true))
+                } else {
+                    Ok(LispExpr::BoolLit(false))
+                }
+            }
+            _ => Err(EvalError::ArgumentCount(Some(1)).into()),
+        }
+    });
+
+    primitive!(env, None, "begin", |args, _| {
+        if args.is_empty() {
+            Err(EvalError::ArgumentCount(None).into())
+        } else {
+            Ok(args.into_iter().last().unwrap().clone())
+        }
+    });
+
+    primitive!(env, Some(0), "quit", |_, app| {
+        app.quit();
+        Ok(LispExpr::Unit)
+    });
+    env
+}