From a547dc711cabcbf986d6c35b0572bef06f553211 Mon Sep 17 00:00:00 2001
From: Erin <erin@erindesu.cz>
Date: Sat, 6 Aug 2022 00:49:25 +0200
Subject: [PATCH] basic formatting

---
 src/interpreter/value/mod.rs | 49 +++++++++++++++++++++++++++++++++---
 1 file changed, 45 insertions(+), 4 deletions(-)

diff --git a/src/interpreter/value/mod.rs b/src/interpreter/value/mod.rs
index 1380e50..9224fa5 100644
--- a/src/interpreter/value/mod.rs
+++ b/src/interpreter/value/mod.rs
@@ -7,12 +7,14 @@ pub use pair::DotPair;
 pub use string::Str;
 
 use crate::syntax::ast::{Expr, Spanned};
-use std::{collections::BTreeMap, rc::Rc};
+use std::{collections::BTreeMap, fmt::Display, rc::Rc};
 
 pub type OrderedF64 = ordered_float::OrderedFloat<f64>;
 
-#[derive(Debug, Clone, PartialEq, Eq)]
+#[derive(Debug, Default, Clone, PartialEq, Eq)]
 pub enum Value<'s> {
+    #[default]
+    Nil,
     DotPair(Rc<DotPair<'s>>),
     Vector(Rc<Vec<Self>>),
     Map(Rc<BTreeMap<Self, Self>>),
@@ -22,7 +24,6 @@ pub enum Value<'s> {
     String(Str<'s>),
     Function(Function),
     Macro(Function),
-    Nil,
 }
 
 impl<'s> From<Spanned<Expr<'s>>> for Value<'s> {
@@ -34,7 +35,9 @@ impl<'s> From<Spanned<Expr<'s>>> for Value<'s> {
 impl<'s> From<Expr<'s>> for Value<'s> {
     fn from(e: Expr<'s>) -> Self {
         match e {
-            Expr::List(_) => todo!(),
+            Expr::List(v) => v.into_iter().rev().fold(Self::Nil, |acc, x| {
+                Value::DotPair(Rc::new(DotPair(x.into(), acc)))
+            }),
             Expr::Vector(v) => Self::Vector(Rc::new(v.into_iter().map(Into::into).collect())),
             Expr::Pair((l, r)) => Self::DotPair(Rc::new(DotPair((*l).into(), (*r).into()))),
             Expr::Quote(e) => Self::DotPair(Rc::new(DotPair(
@@ -48,3 +51,41 @@ impl<'s> From<Expr<'s>> for Value<'s> {
         }
     }
 }
+
+impl<'s> Display for Value<'s> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Value::Nil => "nil".fmt(f),
+            Value::DotPair(p) => write!(f, "({} . {})", p.0, p.1),
+            Value::Vector(v) => fmt_sequence(f, v.as_ref(), "#(", ")", |i, f| i.fmt(f)),
+            Value::Map(m) => {
+                fmt_sequence(f, m.as_ref(), "(", ")", |(k, v), f| write!(f, "{k} -> {v}"))
+            }
+            Value::Symbol(s) => s.fmt(f),
+            Value::Keyword(k) => write!(f, ":{k}"),
+            Value::Number(n) => n.fmt(f),
+            Value::String(s) => write!(f, "\"{s}\""),
+            Value::Function(_) => "#fun#".fmt(f),
+            Value::Macro(_) => "#macro#".fmt(f),
+        }
+    }
+}
+
+fn fmt_sequence<'s, T>(
+    f: &mut std::fmt::Formatter<'_>,
+    s: impl IntoIterator<Item = T>,
+    start: &str,
+    end: &str,
+    it_fmt: impl Fn(T, &mut std::fmt::Formatter<'_>) -> std::fmt::Result,
+) -> std::fmt::Result {
+    let mut it = s.into_iter();
+    start.fmt(f)?;
+    if let Some(i) = it.next() {
+        it_fmt(i, f)?;
+    }
+    for i in it {
+        " ".fmt(f)?;
+        it_fmt(i, f)?;
+    }
+    end.fmt(f)
+}