From 6dec2bd33e6c142664c881405bdc0f9b298e4a11 Mon Sep 17 00:00:00 2001
From: David Robillard <d@drobilla.net>
Date: Sat, 25 Dec 2010 09:24:48 +0000
Subject: Simplify let to fn, rather than deal with it through to compilation.
 The previous implementation of let was a premature optimization intended to
 make let cheap/free, but screws up closure creation and variable indexing
 because a new scope is created by something other than fn.

Only compile top level expressions to globals (with associated store/retrieve overhead) in a REPL when it is necessary.

Add `do' form (ala scheme `begin') to backend (used by `match' simplify).


git-svn-id: http://svn.drobilla.net/resp/resp@348 ad02d1e2-f140-0410-9f75-f8b11f17cedd
---
 src/compile.cpp | 40 ++++++++++++++--------------------------
 1 file changed, 14 insertions(+), 26 deletions(-)

(limited to 'src/compile.cpp')

diff --git a/src/compile.cpp b/src/compile.cpp
index 4c7980e..eed481a 100644
--- a/src/compile.cpp
+++ b/src/compile.cpp
@@ -29,7 +29,7 @@ using namespace std;
 static CVal
 compile_symbol(CEnv& cenv, const ASymbol* sym) throw()
 {
-	if (cenv.vals.topLevel(sym) && cenv.type(sym)->head()->str() != "Fn") {
+	if (cenv.repl && cenv.vals.topLevel(sym) && cenv.type(sym)->head()->str() != "Fn") {
 		return cenv.engine()->compileGlobalGet(cenv, sym->sym(), *cenv.vals.ref(sym));
 	} else {
 		return *cenv.vals.ref(sym);
@@ -67,7 +67,7 @@ compile_def(CEnv& cenv, const ATuple* def) throw()
 	const AST*     const body = def->list_ref(2);
 	cenv.def(sym, body, cenv.type(body), NULL); // define stub first for recursion
 	CVal val = resp_compile(cenv, body);
-	if (cenv.vals.size() == 1 && cenv.type(body)->head()->str() != "Fn") {
+	if (cenv.repl && cenv.vals.size() == 1 && cenv.type(body)->head()->str() != "Fn") {
 		val = cenv.engine()->compileGlobalSet(
 			cenv, sym->str(), val, cenv.type(body));
 		cenv.lock(def);
@@ -76,6 +76,16 @@ compile_def(CEnv& cenv, const ATuple* def) throw()
 	return NULL;
 }
 
+static CVal
+compile_do(CEnv& cenv, const ATuple* ado) throw()
+{
+	CVal retVal = NULL;
+	for (ATuple::const_iterator i = ado->iter_at(1); i != ado->end(); ++i)
+		retVal = resp_compile(cenv, *i);
+
+	return retVal;
+}
+
 static CVal
 compile_fn(CEnv& cenv, const ATuple* fn) throw()
 {
@@ -116,28 +126,6 @@ compile_if(CEnv& cenv, const ATuple* aif) throw()
 	return cenv.engine()->compileIf(cenv, aif->list_ref(1), aif->list_ref(2), aelse);
 }
 
-static CVal
-compile_let(CEnv& cenv, const ATuple* let) throw()
-{
-	const ATuple* vars = let->list_ref(1)->to_tuple();
-
-	cenv.push();
-
-	for (ATuple::const_iterator i = vars->begin(); i != vars->end();) {
-		const ASymbol* sym = (*i++)->to_symbol();
-		const AST*     val = (*i++);
-		cenv.def(sym, val, cenv.type(val), resp_compile(cenv, val));
-	}
-
-	CVal ret = NULL;
-	for (ATuple::const_iterator i = let->iter_at(2); i != let->end(); ++i)
-		ret = resp_compile(cenv, *i);
-
-	cenv.pop();
-
-	return ret;
-}
-
 static CVal
 compile_tag_is(CEnv& cenv, const ATuple* call) throw()
 {
@@ -207,12 +195,12 @@ resp_compile(CEnv& cenv, const AST* ast) throw()
 			return compile_def(cenv, call);
 		else if (form == "def-type")
 			return NULL; // FIXME
+		else if (form == "do")
+			return compile_do(cenv, call);
 		else if (form == "fn")
 			return compile_fn(cenv, call);
 		else if (form == "if")
 			return compile_if(cenv, call);
-		else if (form == "let")
-			return compile_let(cenv, call);
 		else if (form == "__tag_is")
 			return compile_tag_is(cenv, call);
 		else
-- 
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