From 305bf638f823a41f391936712eef302bc6733d00 Mon Sep 17 00:00:00 2001
From: Akshay <nerdy@peppe.rs>
Date: Tue, 23 Mar 2021 18:56:25 +0530
Subject: expose functions to lisp interface, add primitives with macros

---
 src/lisp/env.rs  | 88 +++++++++++++++++++++++---------------------------------
 src/lisp/expr.rs | 19 +++++++++++-
 src/lisp/lex.rs  |  5 +---
 src/lisp/mod.rs  |  2 ++
 4 files changed, 57 insertions(+), 57 deletions(-)

(limited to 'src/lisp')

diff --git a/src/lisp/env.rs b/src/lisp/env.rs
index ad7cc2b..94c0e05 100644
--- a/src/lisp/env.rs
+++ b/src/lisp/env.rs
@@ -1,8 +1,11 @@
 use crate::{
     app::AppState,
     lisp::{error::LispError, expr::LispExpr, number::LispNumber, Environment},
+    primitive,
 };
 
+use log::warn;
+
 pub fn is_bound<S: AsRef<str>>(env: &mut Environment, name: S) -> bool {
     env.get(name.as_ref()).is_some()
 }
@@ -13,21 +16,39 @@ pub fn new_binding<S: AsRef<str>>(env: &mut Environment, name: S, value: LispExp
 
 pub fn with_prelude() -> Environment {
     let mut env = Environment::new();
-    new_binding(
-        &mut env,
-        "+",
-        LispExpr::PrimitiveFunc(|args, _| {
-            if args.iter().any(|arg| !matches!(arg, LispExpr::Number(_))) {
-                Err(LispError::EvalError)
-            } else {
-                let result = args
-                    .iter()
-                    .map(|n| unwrap_number(n))
-                    .fold(LispNumber::Integer(0), |acc, x| acc + *x);
-                Ok(LispExpr::Number(result))
+    primitive!(env, Some(2), "+", |args, _| {
+        if args.iter().any(|arg| !matches!(arg, LispExpr::Number(_))) {
+            Err(LispError::EvalError)
+        } else {
+            Ok(LispExpr::Number(
+                args.iter()
+                    .map(|arg| unwrap_number(arg))
+                    .fold(LispNumber::Integer(0), |acc, x| acc + *x),
+            ))
+        }
+    });
+    primitive!(env, Some(2), "sub", |args, _| {
+        if args.iter().any(|arg| !matches!(arg, LispExpr::Number(_))) {
+            Err(LispError::EvalError)
+        } else {
+            let mut acc = unwrap_number(&args[0]).clone();
+            for arg in args.into_iter().skip(1) {
+                acc = acc - *unwrap_number(&arg);
             }
-        }),
-    );
+            Ok(LispExpr::Number(acc))
+        }
+    });
+    primitive!(env, Some(2), "*", |args, _| {
+        if args.iter().any(|arg| !matches!(arg, LispExpr::Number(_))) {
+            Err(LispError::EvalError)
+        } else {
+            Ok(LispExpr::Number(
+                args.iter()
+                    .map(|arg| unwrap_number(arg))
+                    .fold(LispNumber::Integer(1), |acc, x| acc * *x),
+            ))
+        }
+    });
     env
 }
 
@@ -56,7 +77,7 @@ pub fn eval(expr: &LispExpr, app: &mut AppState) -> Result<LispExpr, LispError>
                             for item in li[1..].iter() {
                                 args.push(eval(item, app)?);
                             }
-                            (f)(&args, None)
+                            f.call(&args, app)
                         }
                         _ => Err(LispError::EvalError),
                     }
@@ -78,40 +99,3 @@ pub fn unwrap_number(n: &LispExpr) -> &LispNumber {
         _ => panic!("unwrap_number expected number"),
     }
 }
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn eval_primitive_call() {
-        let mut env = Environment::new();
-        new_binding(&mut env, "age", LispExpr::Number(LispNumber::Float(1.4)));
-        new_binding(
-            &mut env,
-            "+",
-            LispExpr::PrimitiveFunc(|args, _| {
-                if args.iter().any(|arg| !matches!(arg, LispExpr::Number(_))) {
-                    Err(LispError::EvalError)
-                } else {
-                    let result = args
-                        .iter()
-                        .map(|n| unwrap_number(n))
-                        .fold(LispNumber::Integer(0), |acc, x| acc + *x);
-                    Ok(LispExpr::Number(result))
-                }
-            }),
-        );
-        let mut numbers = (1..=3)
-            .map(LispNumber::Integer)
-            .map(LispExpr::Number)
-            .collect::<Vec<_>>();
-        let mut expr = Vec::new();
-        expr.push(LispExpr::Ident("+".into()));
-        expr.append(&mut numbers);
-        // assert!(matches!(
-        //     eval(&LispExpr::List(expr), ).unwrap(),
-        //     LispExpr::Number(LispNumber::Integer(6))
-        // ));
-    }
-}
diff --git a/src/lisp/expr.rs b/src/lisp/expr.rs
index 4676a3e..adacc1c 100644
--- a/src/lisp/expr.rs
+++ b/src/lisp/expr.rs
@@ -11,7 +11,7 @@ pub enum LispExpr {
     StringLit(String),
     BoolLit(bool),
     Ident(String),
-    PrimitiveFunc(fn(&[LispExpr], Option<&mut AppState>) -> Result<LispExpr, LispError>),
+    PrimitiveFunc(PrimitiveFunc),
     Function(LispFunction),
 
     // none of these depths should be zero
@@ -21,6 +21,23 @@ pub enum LispExpr {
     Quote(Box<LispExpr>, u32),
 }
 
+#[derive(Clone)]
+pub struct PrimitiveFunc {
+    pub arity: Option<usize>,
+    pub closure: fn(&[LispExpr], &mut AppState) -> Result<LispExpr, LispError>,
+}
+
+impl PrimitiveFunc {
+    pub fn call(&self, args: &[LispExpr], app: &mut AppState) -> Result<LispExpr, LispError> {
+        if let Some(arity) = self.arity {
+            if args.len() < arity {
+                return Err(LispError::EvalError);
+            }
+        }
+        (self.closure)(args, app)
+    }
+}
+
 impl LispExpr {
     pub fn comma(self, n: u32) -> LispExpr {
         match self {
diff --git a/src/lisp/lex.rs b/src/lisp/lex.rs
index 3b1389d..30f49fa 100644
--- a/src/lisp/lex.rs
+++ b/src/lisp/lex.rs
@@ -94,10 +94,7 @@ impl<'a> Lexer<'a> {
                     self.cur_pos += ch.len_utf8() as u32;
                     continue;
                 }
-                ch => {
-                    eprintln!("some unexpected character: {}", ch);
-                    Err(LispError::ParseError)
-                }
+                _ => Err(LispError::ParseError),
             };
             let (size, token) = match res {
                 Ok(v) => v,
diff --git a/src/lisp/mod.rs b/src/lisp/mod.rs
index 5166a04..2a19314 100644
--- a/src/lisp/mod.rs
+++ b/src/lisp/mod.rs
@@ -4,6 +4,8 @@ pub mod expr;
 pub mod lex;
 pub mod number;
 pub mod parse;
+#[macro_use]
+mod primitives;
 
 use std::collections::HashMap;
 
-- 
cgit v1.2.3