Make `if` take just one argument

1 files changed, 11 insertions, 11 deletions

diff --git a/prelude.cpp b/prelude.cpp
index 7d9b4c3..f9cf6ff 100644
--- a/prelude.cpp
+++ b/prelude.cpp
@@ -18,7 +18,6 @@ const AST afterBootstrap=AST(R"RAW(
 	(def 'const \x \y x)
 	(def 'print (. putstr repr))
 	(def '$ \f \x (f x))
-	(def 'if \c \t \f (__if c (() t) (() f)))
 	(def 'last \l (if (nil (tail l)) (head l) (last (tail l))))
 	(def 'init \l (if (nil (tail l)) '() (cons (head l) (init (tail l))))))
 )RAW");
@@ -31,6 +30,11 @@ static AST dofunction(const AST&){
 	return doNative;
 }
 
+
+const AST chooseFirstLambda=AST::makeLambda("",AST::makeLambda("",AST::makeIndex(2)));
+const AST chooseSecondLambda=AST::makeLambda("",AST::makeLambda("",AST::makeIndex(1)));
+
+
 class PreludeInit{
 public:
 	PreludeInit(Environment &intoEnv){
@@ -99,17 +103,13 @@ public:
 				return AST::makeNumber(arg.numval==0);
 			}));
 
-		intoEnv.define("__if",checkedHook("__if",{AST::Type::number},{AST::Type::tuple},{AST::Type::tuple},
-			[](Environment&,const AST &arg1,const AST &arg2,const AST &arg3) -> AST {
-				if(arg2.terms.size()!=2||arg3.terms.size()!=2){
-					throw FormError("Then and else arguments to '__if' should be 2-tuples with value in second element");
-				}
-				const AST &choice=arg1.numval!=0?arg2:arg3;
-				AST res=choice.terms[1];
-				if(choice.quoted){
-					res.quoted=true;
+		intoEnv.define("if",checkedHook("if",{AST::Type::number},
+			[](Environment&,const AST &arg) -> AST {
+				if(arg.numval!=0){
+					return chooseFirstLambda;
+				} else {
+					return chooseSecondLambda;
 				}
-				return res;
 			}));
 
 		intoEnv.define("+",checkedHook("+",{AST::Type::number,AST::Type::string},