From e868e7662705967938446ac37cff3fefd1c132cb Mon Sep 17 00:00:00 2001
From: Brian Picciano <mediocregopher@gmail.com>
Date: Sat, 6 Aug 2016 18:40:55 -0600
Subject: [PATCH] fix Identifiers so that Tuples can be assigned to them

---
 expr/build.go |  9 ++++++---
 expr/ctx.go   | 13 ++++---------
 main.go       |  4 ++--
 3 files changed, 12 insertions(+), 14 deletions(-)

diff --git a/expr/build.go b/expr/build.go
index 84ad460..a599861 100644
--- a/expr/build.go
+++ b/expr/build.go
@@ -50,8 +50,8 @@ func (bctx BuildCtx) buildExprTill(e Expr, fn func(e Expr) bool) Expr {
 	case Int:
 		return llvmVal(llvm.ConstInt(llvm.Int64Type(), uint64(ea), false))
 	case Identifier:
-		if v, ok := bctx.C.GetIdentifier(ea); ok {
-			return llvmVal(v)
+		if ev := bctx.C.GetIdentifier(ea); ev != nil {
+			return ev
 		}
 		panicf("identifier %q not found", ea)
 	case Statement:
@@ -85,7 +85,10 @@ var globalCtx = &Ctx{
 		"bind": func(bctx BuildCtx, e Expr) Expr {
 			tup := bctx.buildExprTill(e, isIdentifier).(Tuple)
 			id := bctx.buildExprTill(tup[0], isIdentifier).(Identifier)
-			bctx.C.idents[id] = bctx.buildVal(tup[1])
+			if bctx.C.idents[id] != nil {
+				panicf("identifier %q is already bound", id)
+			}
+			bctx.C.idents[id] = bctx.buildExpr(tup[1])
 			return nil
 		},
 	},
diff --git a/expr/ctx.go b/expr/ctx.go
index da3b979..b54f7d7 100644
--- a/expr/ctx.go
+++ b/expr/ctx.go
@@ -1,7 +1,5 @@
 package expr
 
-import "llvm.org/llvm/bindings/go/llvm"
-
 // MacroFn is a compiler function which takes in an existing Expr and returns
 // the llvm Value for it
 type MacroFn func(BuildCtx, Expr) Expr
@@ -12,7 +10,7 @@ type MacroFn func(BuildCtx, Expr) Expr
 type Ctx struct {
 	global *Ctx
 	macros map[Macro]MacroFn
-	idents map[Identifier]llvm.Value
+	idents map[Identifier]Expr
 }
 
 // NewCtx returns a blank context instance
@@ -20,7 +18,7 @@ func NewCtx() *Ctx {
 	return &Ctx{
 		global: globalCtx,
 		macros: map[Macro]MacroFn{},
-		idents: map[Identifier]llvm.Value{},
+		idents: map[Identifier]Expr{},
 	}
 }
 
@@ -38,12 +36,9 @@ func (c *Ctx) GetMacro(m Macro) MacroFn {
 }
 
 // GetIdentifier returns the llvm.Value for the Identifier, or panics
-func (c *Ctx) GetIdentifier(i Identifier) (llvm.Value, bool) {
-	if v, ok := c.idents[i]; ok {
-		return v, true
-	}
+func (c *Ctx) GetIdentifier(i Identifier) Expr {
 	// The global context doesn't have any identifiers, so don't bother checking
-	return llvm.Value{}, false
+	return c.idents[i]
 }
 
 // NewWith returns a new Ctx instance which imports the given macros from the
diff --git a/main.go b/main.go
index e2052d8..13e358b 100644
--- a/main.go
+++ b/main.go
@@ -37,8 +37,8 @@ func main() {
 	stmts := []expr.Statement{
 		expr.NewStatement(bind, idA, expr.NewStatement(add, expr.Int(1), expr.Int(2))),
 		expr.NewStatement(bind, idB, expr.Int(3)),
-		expr.NewStatement(bind, idC, expr.NewStatement(add, idA, idB)),
-		expr.NewStatement(add, idC, idC),
+		expr.NewStatement(bind, idC, expr.NewTuple(idA, idB)),
+		expr.NewStatement(add, expr.NewStatement(add, idC), expr.NewStatement(add, idC)),
 	}
 
 	//block := expr.Block([]expr.Expr{stmt})