From 04364b75eab3287bb18fe658f28d058f37dd690f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?P=C5=99emysl=20Janouch?= <p.janouch@gmail.com>
Date: Sun, 21 May 2017 11:26:59 +0200
Subject: [PATCH] Add "eq?" and "lt?"

---
 README.adoc |  4 ++--
 ell.c       | 33 ++++++++++++++++++++++++++++++++-
 2 files changed, 34 insertions(+), 3 deletions(-)

diff --git a/README.adoc b/README.adoc
index e1b663c..7bbb17b 100644
--- a/README.adoc
+++ b/README.adoc
@@ -29,7 +29,7 @@ The parser, however, does a bunch of transformations:
 
 As an example, consider the following snippet:
 
- print (if { = @var foo } {
+ print (if { eq? @var foo } {
      quote 'Hello world\n'
  } else {
      quote 'Error\n'
@@ -37,7 +37,7 @@ As an example, consider the following snippet:
 
 which gets expanded to the following:
 
- ((print (if (quote ((= (set var) foo)))
+ ((print (if (quote ((eq? (set var) foo)))
              (quote ((quote 'Hello world\n')))
              else
              (quote ((quote 'Error\n'))))))
diff --git a/ell.c b/ell.c
index 406474f..8a46c6b 100755
--- a/ell.c
+++ b/ell.c
@@ -1159,6 +1159,35 @@ defn (fn_or) {
 	return check (ctx, (*result = new_boolean (res)));
 }
 
+defn (fn_eq) {
+	struct item *etalon = args;
+	if (!etalon || etalon->type != ITEM_STRING)
+		return set_error (ctx, "first argument must be string");
+	bool res = true;
+	for (args = etalon->next; args; args = args->next) {
+		if (args->type != ITEM_STRING)
+			return set_error (ctx, "arguments must be strings");
+		if (!(res &= !strcmp (etalon->value, args->value)))
+			break;
+	}
+	return check (ctx, (*result = new_boolean (res)));
+}
+
+defn (fn_lt) {
+	struct item *etalon = args;
+	if (!etalon || etalon->type != ITEM_STRING)
+		return set_error (ctx, "first argument must be string");
+	bool res = true;
+	for (args = etalon->next; args; args = args->next) {
+		if (args->type != ITEM_STRING)
+			return set_error (ctx, "arguments must be strings");
+		if (!(res &= strcmp (etalon->value, args->value) < 0))
+			break;
+		etalon = args;
+	}
+	return check (ctx, (*result = new_boolean (res)));
+}
+
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 
 static bool
@@ -1209,7 +1238,9 @@ init_runtime_library (struct context *ctx) {
 		&& native_register (ctx, "/",      fn_divide)
 		&& native_register (ctx, "not",    fn_not)
 		&& native_register (ctx, "and",    fn_and)
-		&& native_register (ctx, "or",     fn_or);
+		&& native_register (ctx, "or",     fn_or)
+		&& native_register (ctx, "eq?",    fn_eq)
+		&& native_register (ctx, "lt?",    fn_lt);
 }
 
 // --- Main --------------------------------------------------------------------