🤷 The initial version of the compiler, both static and JIT.

This implements a full compiler, with both static compilation and JIT
support, for the world's simplest and silliest programming language. You
can do math, and print variables. That's it. On the bright side, it
implements every part of the compiler, from the lexer and parser;
through analysis and simplification; and into a reasonable code
generator. This should be a good jumping off point for adding more
advanced features.

Tests, including proptests, are included to help avoid regressions.

src/ir/ast.rs

@@ -0,0 +1,172 @@
+use internment::ArcIntern;
+use pretty::{DocAllocator, Pretty};
+
+use crate::syntax::Location;
+
+type Variable = ArcIntern<String>;
+
+pub struct Program {
+    pub statements: Vec<Statement>,
+}
+
+impl<'a, 'b, D, A> Pretty<'a, D, A> for &'b Program
+where
+    A: 'a,
+    D: ?Sized + DocAllocator<'a, A>,
+{
+    fn pretty(self, allocator: &'a D) -> pretty::DocBuilder<'a, D, A> {
+        let mut result = allocator.nil();
+
+        for stmt in self.statements.iter() {
+            result = result
+                .append(stmt.pretty(allocator))
+                .append(allocator.text(";"))
+                .append(allocator.hardline());
+        }
+
+        result
+    }
+}
+
+pub enum Statement {
+    Binding(Location, Variable, Expression),
+    Print(Location, Variable),
+}
+
+impl<'a, 'b, D, A> Pretty<'a, D, A> for &'b Statement
+where
+    A: 'a,
+    D: ?Sized + DocAllocator<'a, A>,
+{
+    fn pretty(self, allocator: &'a D) -> pretty::DocBuilder<'a, D, A> {
+        match self {
+            Statement::Binding(_, var, expr) => allocator
+                .text(var.as_ref().to_string())
+                .append(allocator.space())
+                .append(allocator.text("="))
+                .append(allocator.space())
+                .append(expr.pretty(allocator)),
+            Statement::Print(_, var) => allocator
+                .text("print")
+                .append(allocator.space())
+                .append(allocator.text(var.as_ref().to_string())),
+        }
+    }
+}
+
+pub enum Expression {
+    Value(Location, Value),
+    Reference(Location, Variable),
+    Primitive(Location, Primitive, Vec<ValueOrRef>),
+}
+
+impl<'a, 'b, D, A> Pretty<'a, D, A> for &'b Expression
+where
+    A: 'a,
+    D: ?Sized + DocAllocator<'a, A>,
+{
+    fn pretty(self, allocator: &'a D) -> pretty::DocBuilder<'a, D, A> {
+        match self {
+            Expression::Value(_, val) => val.pretty(allocator),
+            Expression::Reference(_, var) => allocator.text(var.as_ref().to_string()),
+            Expression::Primitive(_, op, exprs) if exprs.len() == 1 => {
+                op.pretty(allocator).append(exprs[0].pretty(allocator))
+            }
+            Expression::Primitive(_, op, exprs) if exprs.len() == 2 => {
+                let left = exprs[0].pretty(allocator);
+                let right = exprs[1].pretty(allocator);
+
+                left.append(allocator.space())
+                    .append(op.pretty(allocator))
+                    .append(allocator.space())
+                    .append(right)
+                    .parens()
+            }
+            Expression::Primitive(_, op, exprs) => {
+                allocator.text(format!("!!{:?} with {} arguments!!", op, exprs.len()))
+            }
+        }
+    }
+}
+
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub enum Primitive {
+    Plus,
+    Minus,
+    Times,
+    Divide,
+}
+
+impl<'a> TryFrom<&'a str> for Primitive {
+    type Error = String;
+
+    fn try_from(value: &str) -> Result<Self, Self::Error> {
+        match value {
+            "+" => Ok(Primitive::Plus),
+            "-" => Ok(Primitive::Minus),
+            "*" => Ok(Primitive::Times),
+            "/" => Ok(Primitive::Divide),
+            _ => Err(format!("Illegal primitive {}", value)),
+        }
+    }
+}
+
+impl<'a, 'b, D, A> Pretty<'a, D, A> for &'b Primitive
+where
+    A: 'a,
+    D: ?Sized + DocAllocator<'a, A>,
+{
+    fn pretty(self, allocator: &'a D) -> pretty::DocBuilder<'a, D, A> {
+        match self {
+            Primitive::Plus => allocator.text("+"),
+            Primitive::Minus => allocator.text("-"),
+            Primitive::Times => allocator.text("*"),
+            Primitive::Divide => allocator.text("/"),
+        }
+    }
+}
+
+pub enum ValueOrRef {
+    Value(Location, Value),
+    Ref(Location, ArcIntern<String>),
+}
+
+impl<'a, 'b, D, A> Pretty<'a, D, A> for &'b ValueOrRef
+where
+    A: 'a,
+    D: ?Sized + DocAllocator<'a, A>,
+{
+    fn pretty(self, allocator: &'a D) -> pretty::DocBuilder<'a, D, A> {
+        match self {
+            ValueOrRef::Value(_, v) => v.pretty(allocator),
+            ValueOrRef::Ref(_, v) => allocator.text(v.as_ref().to_string()),
+        }
+    }
+}
+
+pub enum Value {
+    Number(Option<u8>, i64),
+}
+
+impl<'a, 'b, D, A> Pretty<'a, D, A> for &'b Value
+where
+    A: 'a,
+    D: ?Sized + DocAllocator<'a, A>,
+{
+    fn pretty(self, allocator: &'a D) -> pretty::DocBuilder<'a, D, A> {
+        match self {
+            Value::Number(opt_base, value) => {
+                let value_str = match opt_base {
+                    None => format!("{}", value),
+                    Some(2) => format!("0b{:b}", value),
+                    Some(8) => format!("0o{:o}", value),
+                    Some(10) => format!("0d{}", value),
+                    Some(16) => format!("0x{:x}", value),
+                    Some(_) => format!("!!{:x}!!", value),
+                };
+
+                allocator.text(value_str)
+            }
+        }
+    }
+}