From 9b3fe7ceb8aa0b0f174a17e6e13b5d325c974979 Mon Sep 17 00:00:00 2001
From: tslil <tslil@posteo.de>
Date: Tue, 5 May 2026 16:39:43 +0100
Subject: repair binding for nesting in for

---
 src/checker.rs           |  1 +
 src/checker_signature.rs | 25 +++++++++----------------
 2 files changed, 10 insertions(+), 16 deletions(-)

(limited to 'src')

diff --git a/src/checker.rs b/src/checker.rs
index c381ba4..2474bab 100644
--- a/src/checker.rs
+++ b/src/checker.rs
@@ -16,6 +16,7 @@ impl CheckerState {
         let Programme(decls) = prog;
 
         for decl in decls {
+            debug!(%decl);
             self.reset_binders();
             match decl {
                 Decl::Set { name, set } => {
diff --git a/src/checker_signature.rs b/src/checker_signature.rs
index 0145e82..cc6cadc 100644
--- a/src/checker_signature.rs
+++ b/src/checker_signature.rs
@@ -371,9 +371,15 @@ impl CheckerState {
 
                 // deal with left-nesting
                 let mut ctx = self.clone();
-                for Param { name, set } in inst_params {
-                    ctx.make_element_binding(name.clone(), set.clone())?;
-                }
+                let inst_params: Vec<Param> = inst_params
+                    .iter()
+                    .map(|Param { name, set }| {
+                        let set = ctx.check_set(set)?;
+                        let canon = ctx.make_element_binding(name.clone(), set.clone())?;
+                        Ok(Param { name: canon, set })
+                    })
+                    .collect::<Result<_, _>>()?;
+
                 let body = ctx.check_instance(body, None)?;
                 let (inst_params, body) = if let Instance::For {
                     params: inner_params,
@@ -467,19 +473,6 @@ impl CheckerState {
                         params: inst_params,
                     })
                 } else {
-                    let mut ctx = self.clone();
-                    let inst_params = inst_params
-                        .iter()
-                        .map(|Param { name, set }| {
-                            let set = ctx.check_set(set)?;
-                            let canon = ctx.make_element_binding(name.clone(), set.clone())?;
-                            Ok(Param {
-                                name: canon,
-                                set: set,
-                            })
-                        })
-                        .collect::<Result<Vec<_>, _>>()?;
-                    let body = ctx.check_instance(&body, None)?;
                     Ok(Instance::For {
                         params: inst_params,
                         body: Box::new(body),
-- 
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