Add some display for each, order of operations won't be correct without context

src/emitter.rs

@@ -78,13 +78,6 @@ pub fn emit(w: &mut dyn Write, stmt: &parser::Stmt, ctx: &mut LexicalContext) ->
 		writeln!(w, "return;")?;
 	    }
 	}
-	parser::Stmt::Funcall(call) => {
-	    if ctx.is_tail {
-		write!(w, "return ")?;
-	    }
-	    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 {

src/parser.rs

@@ -3,7 +3,6 @@ use std::fmt;
 #[derive(Debug,PartialEq,Clone)]
 pub enum Stmt {
     Assignment(String, Expr),
-    Funcall(Expr),
     Conditional(Vec<GuardedBlock>, Option<Block>),
     Loop(Loop),
     BareExpr(Expr),
@@ -34,16 +33,6 @@ pub enum Atom {
     Bool(bool),
 }
 
-impl fmt::Display for Atom {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        match self {
-            Atom::String(a) => write!(f, "\"{}\"", a),
-            Atom::Num(a) => write!(f, "{}", a),
-	    Atom::Bool(a) => write!(f, "{}", a),
-        }
-    }
-}
-
 #[derive(Debug,PartialEq,Clone)]
 pub struct GuardedBlock {
     pub guard: Expr,
@@ -63,7 +52,6 @@ peg::parser! {
             = __*  s:stmt()* { s }
         pub rule stmt() -> Stmt
             = a:assignment() { a } /
-            f:funcall() stop() { Stmt::Funcall(f) } /
             c:conditional() { c } /
 	    l:_loop() { Stmt::Loop(l) } / 
             e:expr() stop() { Stmt::BareExpr(e) }
@@ -215,6 +203,86 @@ pub fn parse_stmt(stmt: &str) -> Stmt {
     deelang_parser::stmt(&stmt).unwrap()
 }
 
+impl fmt::Display for Stmt {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+	match self {
+	    Stmt::Assignment(id, expr) => writeln!(f, "{} <- {}", id, expr),
+	    Stmt::BareExpr(expr) => writeln!(f, "{}", expr),
+	    Stmt::Conditional(guarded_blocks, else_block) => {
+		let (if_block, elif_blocks) = guarded_blocks.split_first().unwrap();
+		write!(f, "if {}", if_block.guard)?;
+		write_block(f, &if_block.block)?;
+		for elif_block in elif_blocks {
+		    write!(f, "elif {}", elif_block.guard)?;
+		    write_block(f, &if_block.block)?;
+		}
+		if let Some(block) = else_block {
+		    write!(f, "else")?;
+		    write_block(f, &block)?;
+		}
+		Ok(())
+	    }
+	    Stmt::Loop(loop_inner) => match &loop_inner {
+		Loop::Bare(block) => {
+		    write!(f, "loop")?;
+		    write_block(f, block)
+		}
+		Loop::Over(id, pred, block) => {
+		    write!(f, "loop over {} in {}", id, pred)?;
+		    write_block(f, block)
+		}
+		Loop::Until(guarded_block) => {
+		    write!(f, "loop until {}", guarded_block.guard)?;
+		    write_block(f, &guarded_block.block)
+		}
+	    },
+	}
+    }
+}
+
+fn write_block (f: &mut fmt::Formatter<'_>, block: &Block) -> fmt::Result {
+    if block.len() == 1 {
+	writeln!(f, " {}", block[0])
+    } else {
+	writeln!(f)?;
+	writeln!(f, ">>>")?;
+	for stmt in block {
+	    write!(f, "{}", stmt)?;
+	}
+	writeln!(f, "<<<")
+    }
+}
+
+impl fmt::Display for Expr {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+	match self {
+	    Expr::Atom(a) => write!(f, "{}", a),
+	    Expr::Id(id) => write!(f, "{}", id),
+	    Expr::Equal(e1, e2) => write!(f, "{} = {}", e1, e2),
+	    Expr::Relop(op, e1, e2) => write!(f, "{} {} {}", e1, op, e2),
+	    Expr::Plus(e1, e2) => write!(f, "{} + {}", e1, e2),
+	    Expr::Minus(e1, e2) => write!(f, "{} - {}", e1, e2),
+	    Expr::Div(e1, e2) => write!(f, "{} / {}", e1, e2),
+	    Expr::Mult(e1, e2) => write!(f, "{} * {}", e1, e2),
+	    Expr::Mod(e1, e2) => write!(f, "{} % {}", e1, e2),
+	    Expr::UnaryMinus(e) => write!(f, "-{}", e),
+
+	    Expr::Funcdef(_arg, _block) => todo!(),
+	    Expr::Funcall(_id, _args) => todo!(),
+	}
+    }
+}
+
+impl fmt::Display for Atom {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Atom::String(a) => write!(f, "\"{}\"", a),
+            Atom::Num(a) => write!(f, "{}", a),
+	    Atom::Bool(a) => write!(f, "{}", a),
+        }
+    }
+}
+
 
 #[cfg(test)]
 mod test {
@@ -232,8 +300,8 @@ apple <- 1 ## This is too
     #[test]
     fn test_funcall() {
         let expected = vec![
-            Stmt::Funcall(Expr::Funcall("pear".to_string(), vec![])),
-            Stmt::Funcall(Expr::Funcall("pear".to_string(),
+            Stmt::BareExpr(Expr::Funcall("pear".to_string(), vec![])),
+            Stmt::BareExpr(Expr::Funcall("pear".to_string(),
                                         vec![Expr::Id("x".to_string()), Expr::Id("y".to_string())],
             ))
         ];
@@ -326,8 +394,8 @@ foo <- x -> y -> x * y";
                 Expr::Funcdef(
                     None,
 		    vec![
-                        Stmt::Funcall(Expr::Funcall("bar".to_string(), vec![])),
-                        Stmt::Funcall(Expr::Funcall("baz".to_string(), vec![])),
+                        Stmt::BareExpr(Expr::Funcall("bar".to_string(), vec![])),
+                        Stmt::BareExpr(Expr::Funcall("baz".to_string(), vec![])),
                     ],
 		)
             ),
@@ -366,14 +434,14 @@ else
             vec![
                 GuardedBlock {
                     guard: Expr::Id("foo".to_string()),
-                    block: vec![Stmt::Funcall(Expr::Funcall("bar".to_string(), vec![]))]
+                    block: vec![Stmt::BareExpr(Expr::Funcall("bar".to_string(), vec![]))]
                 },
                 GuardedBlock {
                     guard: Expr::Id("baz".to_string()),
-                    block: vec![Stmt::Funcall(Expr::Funcall("foobar".to_string(), vec![]))],
+                    block: vec![Stmt::BareExpr(Expr::Funcall("foobar".to_string(), vec![]))],
                 },
             ],
-            Some(vec![Stmt::Funcall(Expr::Funcall("quux".to_string(), vec![]))]),
+            Some(vec![Stmt::BareExpr(Expr::Funcall("quux".to_string(), vec![]))]),
         )];
         assert_eq!(deelang_parser::program(prgm).unwrap(), expected);
     }