From ff516c39acba7ade6f4827503c08ce6a7169be85 Mon Sep 17 00:00:00 2001
From: Rob Rix <rob.rix@me.com>
Date: Tue, 1 Feb 2022 14:12:06 -0500
Subject: [PATCH] Define a let' macro.

---
 semantic-analysis/src/Analysis/Syntax.hs | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/semantic-analysis/src/Analysis/Syntax.hs b/semantic-analysis/src/Analysis/Syntax.hs
index 73bd1dd53..9e012b032 100644
--- a/semantic-analysis/src/Analysis/Syntax.hs
+++ b/semantic-analysis/src/Analysis/Syntax.hs
@@ -21,6 +21,8 @@ module Analysis.Syntax
 , eval0
 , eval
 , Interpret(..)
+  -- * Macro-expressible syntax
+, let'
   -- * Parsing
 , parseFile
 , parseGraph
@@ -28,8 +30,9 @@ module Analysis.Syntax
 ) where
 
 import           Analysis.Effect.Domain
-import           Analysis.Effect.Env (Env)
+import           Analysis.Effect.Env (Env, bind)
 import           Analysis.Effect.Store
+import           Analysis.Name (Name)
 import           Control.Applicative (Alternative(..), liftA3)
 import           Control.Effect.Labelled
 import           Control.Monad (guard)
@@ -115,6 +118,15 @@ instance (Has (Env addr) sig m, HasLabelled Store (Store addr val) sig m, Has (D
   throw e = Interpret (\ eval -> eval e >>= ddie)
 
 
+-- Macro-expressible syntax
+
+let' :: (Has (Env addr) sig m, HasLabelled Store (Store addr val) sig m) => Name -> val -> m a -> m a
+let' n v m = do
+  addr <- alloc n
+  addr .= v
+  bind n addr m
+
+
 -- Parsing
 
 parseFile :: Syntax rep => FilePath -> IO (Either (A.JSONPath, String) (IntMap.IntMap rep))