feat: add foregin exprssions and vec3 functions

Cargo.lock

@@ -2,6 +2,12 @@
 # It is not intended for manual editing.
 version = 3
 
+[[package]]
+name = "as-any"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5b8a30a44e99a1c83ccb2a6298c563c888952a1c9134953db26876528f84c93a"
+
 [[package]]
 name = "autocfg"
 version = "1.4.0"
@@ -125,6 +131,7 @@ checksum = "8e9489c2807c139ffd9c1794f4af0ebe86a828db53ecdc7fea2111d0fed085d1"
 name = "lispers"
 version = "0.1.0"
 dependencies = [
+ "as-any",
  "futures",
  "nix",
 ]

Cargo.toml

@@ -7,5 +7,6 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
+as-any = "0.3.1"
 futures = "0.3.30"
 nix = "0.29.0"

src/lisp/environment.rs

@@ -1,4 +1,4 @@
-use super::{expression::Expression, prelude::mk_prelude};
+use super::{expression::Expression, prelude::mk_prelude, vec::mk_vec3};
 use std::{cell::RefCell, collections::HashMap, rc::Rc};
 
 #[derive(PartialEq, Clone, Debug)]
@@ -124,12 +124,13 @@ impl<'a> Environment<'a> {
 }
 
 impl Default for Environment<'_> {
-    /// Get the default prelude layer
+    /// Get the default prelude+vec3 layer
     fn default() -> Self {
-        let mut prelude = EnvironmentLayer::new();
-        mk_prelude(&mut prelude);
+        let mut d = EnvironmentLayer::new();
+        mk_prelude(&mut d);
+        mk_vec3(&mut d);
         Environment {
-            layer: prelude,
+            layer: d,
             outer: None,
             shared: Rc::new(RefCell::new(EnvironmentLayer::new())),
         }

src/lisp/expression.rs

@@ -1,9 +1,64 @@
+use std::fmt::Debug;
 use std::fmt::Display;
 
+use as_any::AsAny;
+
 use super::environment::Environment;
 use super::eval::CellIterator;
 use super::eval::EvalError;
 
+/// A trait for foreign data types that can be used in lisp expressions.
+/// Note: This trait requires explicit implementation of:
+/// - partial_cmp
+/// - clone_data
+/// - eq
+/// To avoid a derive cycle.
+pub trait ForeignData: Debug + Display + AsAny {
+    fn partial_cmp(&self, other: &dyn ForeignData) -> Option<std::cmp::Ordering>;
+    fn clone_data(&self) -> Box<dyn ForeignData>;
+    fn eq(&self, other: &dyn ForeignData) -> bool;
+}
+
+#[derive(Debug)]
+/// A Wrapper struct for foreign data types injected in expressions.
+pub struct ForeignDataWrapper {
+    /// The actual foreign data.
+    pub data: Box<dyn ForeignData>,
+}
+
+impl ForeignDataWrapper {
+    /// Create a new ForeignDataWrapper from a ForeignData trait object.
+    pub fn new(data: Box<dyn ForeignData>) -> Self {
+        ForeignDataWrapper { data }
+    }
+}
+
+impl Clone for ForeignDataWrapper {
+    fn clone(&self) -> Self {
+        ForeignDataWrapper {
+            data: self.data.clone_data(),
+        }
+    }
+}
+
+impl PartialEq for ForeignDataWrapper {
+    fn eq(&self, other: &Self) -> bool {
+        self.data.eq(other.data.as_ref())
+    }
+}
+
+impl PartialOrd for ForeignDataWrapper {
+    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
+        self.data.partial_cmp(other.data.as_ref())
+    }
+}
+
+impl Display for ForeignDataWrapper {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}", self.data)
+    }
+}
+
 #[derive(Clone, Debug, PartialEq, PartialOrd)]
 /// A sum type of all possible lisp expressions.
 pub enum Expression {
@@ -16,6 +71,8 @@ pub enum Expression {
         argument_symbols: Vec<String>,
         body: Box<Expression>,
     },
+    /// A foreign data expression.
+    ForeignExpression(ForeignDataWrapper),
     /// A Quoted expression.
     Quote(Box<Expression>),
     /// A symbol.
@@ -155,6 +212,7 @@ impl TryFrom<Expression> for (Expression, Expression) {
 impl Display for Expression {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
+            Expression::ForeignExpression(e) => write!(f, "{}", e),
             Expression::Cell(a, b) => {
                 match self.clone().try_into() as Result<Vec<Expression>, EvalError> {
                     Ok(lst) => write!(

src/lisp/mod.rs

@@ -2,9 +2,8 @@ pub mod environment;
 pub mod eval;
 pub mod expression;
 pub mod prelude;
+pub mod vec;
 
 pub use environment::Environment;
-pub use environment::EnvironmentLayer;
 pub use eval::eval;
-pub use eval::EvalError;
 pub use expression::Expression;

src/lisp/vec.rs

@@ -0,0 +1,96 @@
+use std::fmt::Display;
+
+use as_any::AsAny;
+
+use super::{
+    environment::{Environment, EnvironmentLayer},
+    eval::{eval, EvalError},
+    expression::ForeignData,
+    expression::{Expression, ForeignDataWrapper},
+};
+
+#[derive(Debug, Clone, Copy)]
+/// A simple 3d vector.
+struct Vec3 {
+    x: f64,
+    y: f64,
+    z: f64,
+}
+
+impl Display for Vec3 {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "(vec3 {} {} {})", self.x, self.y, self.z)
+    }
+}
+
+impl ForeignData for Vec3 {
+    fn clone_data(&self) -> Box<dyn ForeignData> {
+        Box::new(*self)
+    }
+    fn eq(&self, other: &dyn ForeignData) -> bool {
+        if let Some(other) = other.as_any().downcast_ref::<Vec3>() {
+            self.x == other.x && self.y == other.y && self.z == other.z
+        } else {
+            false
+        }
+    }
+    fn partial_cmp(&self, other: &dyn ForeignData) -> Option<std::cmp::Ordering> {
+        if let Some(other) = other.as_any().downcast_ref::<Vec3>() {
+            Some(
+                self.x
+                    .partial_cmp(&other.x)?
+                    .then(self.y.partial_cmp(&other.y)?)
+                    .then(self.z.partial_cmp(&other.z)?),
+            )
+        } else {
+            None
+        }
+    }
+}
+
+impl TryFrom<Expression> for Vec3 {
+    type Error = EvalError;
+    fn try_from(value: Expression) -> Result<Self, Self::Error> {
+        match value {
+            Expression::ForeignExpression(fe) => {
+                if let Some(vec) = fe.data.as_ref().as_any().downcast_ref::<Vec3>() {
+                    Ok(*vec)
+                } else {
+                    Err(EvalError::TypeError("Expected vec3".to_string()))
+                }
+            }
+            _ => Err(EvalError::TypeError("Expected vec3".to_string())),
+        }
+    }
+}
+
+/// Create a vec3 expression from a list of 3 floats
+pub fn vec_vec(_env: &Environment, expr: Expression) -> Result<Expression, EvalError> {
+    let [x, y, z]: [f64; 3] = expr.try_into()?;
+
+    Ok(Expression::ForeignExpression(ForeignDataWrapper::new(
+        Box::new(Vec3 { x, y, z }),
+    )))
+}
+
+/// Add two vec3 expressions
+pub fn vec_add(env: &Environment, expr: Expression) -> Result<Expression, EvalError> {
+    let [a, b]: [Expression; 2] = expr.try_into()?;
+
+    let a = Vec3::try_from(eval(env, a)?)?;
+    let b = Vec3::try_from(eval(env, b)?)?;
+
+    Ok(Expression::ForeignExpression(ForeignDataWrapper::new(
+        Box::new(Vec3 {
+            x: a.x + b.x,
+            y: a.y + b.y,
+            z: a.z + b.z,
+        }),
+    )))
+}
+
+/// Add vec3 functions to a layer
+pub fn mk_vec3(layer: &mut EnvironmentLayer) {
+    layer.set("vec3".to_string(), Expression::Function(vec_vec));
+    layer.set("vec3-add".to_string(), Expression::Function(vec_add));
+}

src/main.rs

@@ -15,6 +15,7 @@ fn main() {
         "pow",
         "(pow 2 10)",
         "(let '((fib . (lambda (n) (if (< n 2) n (+ (fib (- n 1)) (fib (- n 2))))))) (fib 10))",
+        "(vec3-add (vec3 1.0 2.0 3.0) (vec3 4.0 5.0 6.0))",
     ];
 
     let environment = Environment::default();