From 8ef49564205633004d21fb74b8ad58504201f893 Mon Sep 17 00:00:00 2001
From: Lukasz Czajka <lukasz@heliax.dev>
Date: Wed, 15 Jan 2025 12:26:09 +0100
Subject: [PATCH] Language.Context

---
 Juvix/Core/Main/Language/Context.lean | 39 +++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)
 create mode 100644 Juvix/Core/Main/Language/Context.lean

diff --git a/Juvix/Core/Main/Language/Context.lean b/Juvix/Core/Main/Language/Context.lean
new file mode 100644
index 0000000..feed2ae
--- /dev/null
+++ b/Juvix/Core/Main/Language/Context.lean
@@ -0,0 +1,39 @@
+
+import Juvix.Core.Main.Language.Base
+
+namespace Juvix.Core.Main
+
+
+inductive Context : Type where
+  | hole : Context
+  | app_left : Context → Expr → Context
+  | app_right : Expr → Context → Context
+  | constr_app_left : Context → Expr → Context
+  | constr_app_right : Expr → Context → Context
+  | binop_left : (oper : BinaryOp) → (arg₁ : Context) → (arg₂ : Expr) → Context
+  | binop_right : (oper : BinaryOp) → (arg₁ : Expr) → (arg₂ : Context) → Context
+  | lambda : (body : Context) → Context
+  | save_left : (value : Context) → (body : Expr) → Context
+  | save_right : (value : Expr) → (body : Context) → Context
+  | branch_left : (constr : Name) → (body : Context) → (next : Expr) → Context
+  | branch_right : (constr : Name) → (body : Expr) → (next : Context) → Context
+  | default : (body : Context) → Context
+  deriving Inhabited, BEq, DecidableEq
+
+def Context.subst (C : Context) (e : Expr) : Expr :=
+  match C with
+  | Context.hole => e
+  | Context.app_left C' e' => Expr.app (C'.subst e) e'
+  | Context.app_right e' C' => Expr.app e' (C'.subst e)
+  | Context.constr_app_left C' e' => Expr.constr_app (C'.subst e) e'
+  | Context.constr_app_right e' C' => Expr.constr_app e' (C'.subst e)
+  | Context.binop_left oper C₁ e₂ => Expr.binop oper (C₁.subst e) e₂
+  | Context.binop_right oper e₁ C₂ => Expr.binop oper e₁ (C₂.subst e)
+  | Context.lambda C' => Expr.lambda (C'.subst e)
+  | Context.save_left C' e' => Expr.save (C'.subst e) e'
+  | Context.save_right e' C' => Expr.save e' (C'.subst e)
+  | Context.branch_left constr C' next => Expr.branch constr (C'.subst e) next
+  | Context.branch_right constr body C' => Expr.branch constr body (C'.subst e)
+  | Context.default C' => Expr.default (C'.subst e)
+
+end Juvix.Core.Main