refactor(users/glittershark): Rename to grfn r/2485

Rename my //users directory and all places that refer to glittershark to
grfn, including nix references and documentation.

This may require some extra attention inside of gerrit's database after
it lands to allow me to actually push things.

Change-Id: I4728b7ec2c60024392c1c1fa6e0d4a59b3e266fa
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2933
Tested-by: BuildkiteCI
Reviewed-by: tazjin <mail@tazj.in>
Reviewed-by: lukegb <lukegb@tvl.fyi>
Reviewed-by: glittershark <grfn@gws.fyi>

1 files changed, 189 insertions, 0 deletions

diff --git a/users/grfn/achilles/src/passes/hir/strip_positive_units.rs b/users/grfn/achilles/src/passes/hir/strip_positive_units.rs
new file mode 100644
index 0000000000..91b56551c8
--- /dev/null
+++ b/users/grfn/achilles/src/passes/hir/strip_positive_units.rs
@@ -0,0 +1,189 @@
+use std::collections::HashMap;
+use std::mem;
+
+use ast::hir::Binding;
+use ast::Literal;
+use void::{ResultVoidExt, Void};
+
+use crate::ast::hir::{Decl, Expr};
+use crate::ast::{self, Ident};
+
+use super::Visitor;
+
+/// Strip all values with a unit type in positive (non-return) position
+pub(crate) struct StripPositiveUnits {}
+
+impl<'a, 'ast> Visitor<'a, 'ast, ast::Type<'ast>> for StripPositiveUnits {
+    type Error = Void;
+
+    fn pre_visit_expr(
+        &mut self,
+        expr: &mut Expr<'ast, ast::Type<'ast>>,
+    ) -> Result<(), Self::Error> {
+        let mut extracted = vec![];
+        if let Expr::Call { args, .. } = expr {
+            // TODO(grfn): replace with drain_filter once it's stabilized
+            let mut i = 0;
+            while i != args.len() {
+                if args[i].type_() == &ast::Type::Unit {
+                    let expr = args.remove(i);
+                    if !matches!(expr, Expr::Literal(Literal::Unit, _)) {
+                        extracted.push(expr)
+                    };
+                } else {
+                    i += 1
+                }
+            }
+        }
+
+        if !extracted.is_empty() {
+            let body = mem::replace(expr, Expr::Literal(Literal::Unit, ast::Type::Unit));
+            *expr = Expr::Let {
+                bindings: extracted
+                    .into_iter()
+                    .map(|expr| Binding {
+                        ident: Ident::from_str_unchecked("___discarded"),
+                        type_: expr.type_().clone(),
+                        body: expr,
+                    })
+                    .collect(),
+                type_: body.type_().clone(),
+                body: Box::new(body),
+            };
+        }
+
+        Ok(())
+    }
+
+    fn post_visit_call(
+        &mut self,
+        _fun: &mut Expr<'ast, ast::Type<'ast>>,
+        _type_args: &mut HashMap<Ident<'ast>, ast::Type<'ast>>,
+        args: &mut Vec<Expr<'ast, ast::Type<'ast>>>,
+    ) -> Result<(), Self::Error> {
+        args.retain(|arg| arg.type_() != &ast::Type::Unit);
+        Ok(())
+    }
+
+    fn visit_type(&mut self, type_: &mut ast::Type<'ast>) -> Result<(), Self::Error> {
+        if let ast::Type::Function(ft) = type_ {
+            ft.args.retain(|a| a != &ast::Type::Unit);
+        }
+        Ok(())
+    }
+
+    fn post_visit_fun_decl(
+        &mut self,
+        _name: &mut Ident<'ast>,
+        _type_args: &mut Vec<Ident>,
+        args: &mut Vec<(Ident, ast::Type<'ast>)>,
+        _body: &mut Box<Expr<ast::Type<'ast>>>,
+        _type_: &mut ast::Type<'ast>,
+    ) -> Result<(), Self::Error> {
+        args.retain(|(_, ty)| ty != &ast::Type::Unit);
+        Ok(())
+    }
+}
+
+pub(crate) fn run_toplevel<'a>(toplevel: &mut Vec<Decl<'a, ast::Type<'a>>>) {
+    let mut pass = StripPositiveUnits {};
+    for decl in toplevel.iter_mut() {
+        pass.visit_decl(decl).void_unwrap();
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::parser::toplevel;
+    use crate::tc::typecheck_toplevel;
+    use pretty_assertions::assert_eq;
+
+    #[test]
+    fn unit_only_arg() {
+        let (_, program) = toplevel(
+            "ty f : fn () -> int
+             fn f _ = 1
+
+             ty main : fn -> int
+             fn main = f ()",
+        )
+        .unwrap();
+
+        let (_, expected) = toplevel(
+            "ty f : fn -> int
+             fn f = 1
+
+             ty main : fn -> int
+             fn main = f()",
+        )
+        .unwrap();
+        let expected = typecheck_toplevel(expected).unwrap();
+
+        let mut program = typecheck_toplevel(program).unwrap();
+        run_toplevel(&mut program);
+
+        assert_eq!(program, expected);
+    }
+
+    #[test]
+    fn unit_and_other_arg() {
+        let (_, program) = toplevel(
+            "ty f : fn (), int -> int
+             fn f _ x = x
+
+             ty main : fn -> int
+             fn main = f () 1",
+        )
+        .unwrap();
+
+        let (_, expected) = toplevel(
+            "ty f : fn int -> int
+             fn f x = x
+
+             ty main : fn -> int
+             fn main = f 1",
+        )
+        .unwrap();
+        let expected = typecheck_toplevel(expected).unwrap();
+
+        let mut program = typecheck_toplevel(program).unwrap();
+        run_toplevel(&mut program);
+
+        assert_eq!(program, expected);
+    }
+
+    #[test]
+    fn unit_expr_and_other_arg() {
+        let (_, program) = toplevel(
+            "ty f : fn (), int -> int
+             fn f _ x = x
+
+             ty g : fn int -> ()
+             fn g _ = ()
+
+             ty main : fn -> int
+             fn main = f (g 2) 1",
+        )
+        .unwrap();
+
+        let (_, expected) = toplevel(
+            "ty f : fn int -> int
+             fn f x = x
+
+             ty g : fn int -> ()
+             fn g _ = ()
+
+             ty main : fn -> int
+             fn main = let ___discarded = g 2 in f 1",
+        )
+        .unwrap();
+        assert_eq!(expected.len(), 6);
+        let expected = typecheck_toplevel(expected).unwrap();
+
+        let mut program = typecheck_toplevel(program).unwrap();
+        run_toplevel(&mut program);
+
+        assert_eq!(program, expected);
+    }
+}