WIP to think about tail calls etc

src/emitter.rs

@@ -5,14 +5,16 @@ use crate::parser;
 
 pub struct LexicalContext<'a> {
     parent: Option<&'a LexicalContext<'a>>,
-    local: HashSet<String>
+    local: HashSet<String>,
+    is_tail: bool,
 }
 
 impl <'a> LexicalContext<'a> {
     pub fn toplevel() -> Self {
 	LexicalContext {
 	    parent: None,
-	    local: HashSet::new()
+	    local: HashSet::new(),
+	    is_tail: false,
 	}
     }
     #[allow(dead_code)]
@@ -20,6 +22,7 @@ impl <'a> LexicalContext<'a> {
 	LexicalContext {
 	    parent: Some(parent),
 	    local: HashSet::new(),
+	    is_tail: false,
 	}
     }
     fn contains(&self, s: &str) -> bool {
@@ -53,7 +56,32 @@ pub fn emit(w: &mut dyn Write, stmt: &parser::Stmt, ctx: &mut LexicalContext) ->
 	    emit_expr(w, expr, ctx)?;
 	    writeln!(w, ";")?;
 	}
-	_ => todo!(),
+	parser::Stmt::Funcall(call) => {
+	    emit_expr(w, call, ctx)?;
+	    writeln!(w, ";")?;
+	}
+	parser::Stmt::Conditional(if_blocks, else_block) => {
+	    let mut first_block = true;
+	    for if_block in if_blocks {
+		if first_block {
+		    write!(w, "if (")?;
+		} else {
+		    write!(w, " else if(")?;
+		}
+		first_block = false;
+		emit_expr(w, &if_block.guard, ctx)?;
+		writeln!(w, ") {{")?;
+		let mut block_ctx = LexicalContext::new(ctx);
+		emit_expr(w, &if_block.block, &mut block_ctx)?;
+		writeln!(w, "}}")?;
+	    }
+	    if let Some(block) = else_block {
+		writeln!(w, "else {{")?;
+		let mut block_ctx = LexicalContext::new(ctx);
+		emit_expr(w, block, &mut block_ctx)?;
+		writeln!(w, "}}")?;
+	    }
+	}
     }
     Ok(())
 }
@@ -66,6 +94,42 @@ pub fn emit_expr(w: &mut dyn Write, expr: &parser::Expr, ctx: &mut LexicalContex
 	parser::Expr::Atom(atom) => {
 	    write!(w, "{}", atom)?;
 	}
+	parser::Expr::Funcall(id, args) => {
+	    write!(w, "{}", id)?;
+	    if args.is_empty() {
+		write!(w, "()")?;
+	    }
+	    for arg in args {
+		write!(w, "(")?;
+		emit_expr(w, arg, ctx)?;
+		write!(w, ")")?;
+	    }
+	}
+	parser::Expr::Funcdef(arg, body) => {
+	    if let Some(arg) = arg {
+		writeln!(w, "function ({}){{", arg)?;
+	    } else {
+		writeln!(w, "function (){{")?;
+	    }
+	    let mut fun_ctx = LexicalContext::new(ctx);
+	    fun_ctx.is_tail = true;
+	    emit_expr(w, body.as_ref(), &mut fun_ctx)?;
+	    write!(w, "}}")?;
+	}
+	parser::Expr::Block(stmts) => {
+	    let mut peek_iter = stmts.iter().peekable();
+	    while let Some(stmt) = peek_iter.next() {
+		if peek_iter.peek().is_none() {
+		    write!(w, "return ")?;
+		}
+		emit(w, stmt, ctx)?;
+	    }
+	}   
+	parser::Expr::Plus(e1, e2) => {
+	    emit_expr(w, e1.as_ref(), ctx)?;
+	    write!(w, " + ")?;
+	    emit_expr(w, e2.as_ref(), ctx)?;
+	}
 	_ => todo!(),
     }
     Ok(())

src/evaluator.rs

@@ -49,9 +49,11 @@ pub fn eval(ast: &parser::Stmt, env: &mut Env) {
                 match res {
                     Atom::Bool(true) => {
                         matched = true;
-                        for stmt in block {
-                            eval(stmt, env);
-                        }
+			if let parser::Expr::Block(block) = block {
+                            for stmt in block {
+				eval(stmt, env);
+                            }
+			}
                         break;
                     }
                     Atom::Bool(false) => continue,

src/parser.rs

@@ -43,7 +43,7 @@ impl fmt::Display for Atom {
 #[derive(Debug,PartialEq,Clone)]
 pub struct GuardedBlock {
     pub guard: Expr,
-    pub block: Vec<Stmt>,
+    pub block: Expr,
 }
 
 peg::parser! {
@@ -93,14 +93,14 @@ peg::parser! {
             = "{" _ stop() indent() __* a:assignment()+ dedent() __* "}" _ { Expr::Object(a) }
         
         rule _if() -> GuardedBlock
-            = "if" _ g:expr() b:indented_block() {
+            = "if" _ g:expr() b:block() {
                 GuardedBlock {
                     guard: g,
                     block: b,
                 }
             }
         rule elif() -> GuardedBlock
-            = "elif" _ g:expr() b:indented_block() {
+            = "elif" _ g:expr() b:block() {
                 GuardedBlock {
                     guard: g,
                     block: b
@@ -333,11 +333,11 @@ else
             vec![
                 GuardedBlock {
                     guard: Expr::Id("foo".to_string()),
-                    block: vec![Stmt::Funcall(Expr::Funcall("bar".to_string(), vec![]))]
+                    block: Expr::Block(vec![Stmt::Funcall(Expr::Funcall("bar".to_string(), vec![]))])
                 },
                 GuardedBlock {
                     guard: Expr::Id("baz".to_string()),
-                    block: vec![Stmt::Funcall(Expr::Funcall("foobar".to_string(), vec![]))]
+                    block: Expr::Block(vec![Stmt::Funcall(Expr::Funcall("foobar".to_string(), vec![]))])
                 },
             ],
             Some(Expr::Block(vec![Stmt::Funcall(Expr::Funcall("quux".to_string(), vec![]))])),