From cbce0d649816cb782f2d2932e8aa74edfda64da1 Mon Sep 17 00:00:00 2001
From: Přemysl Janouch <p.janouch@gmail.com>
Date: Sun, 21 May 2017 00:23:51 +0200
Subject: Fix for, map, filter

---
 ell.c     | 51 +++++++++++++++++++++++++++++----------------------
 greet.ell |  9 +++++++--
 2 files changed, 36 insertions(+), 24 deletions(-)

diff --git a/ell.c b/ell.c
index 0e6b550..cc38579 100755
--- a/ell.c
+++ b/ell.c
@@ -765,6 +765,13 @@ execute_args (struct context *ctx, struct item *args, struct item **res) {
 	return true;
 }
 
+static bool
+set_arg (struct context *ctx, size_t arg, struct item *value) {
+	char buf[64];
+	(void) snprintf (buf, sizeof buf, "%zu", arg);
+	return set (ctx, buf, value);
+}
+
 // TODO: we should probably maintain arguments in a separate list,
 //   either that or at least remember the count so that we can reset them
 static bool
@@ -776,12 +783,9 @@ execute_and_set_args (struct context *ctx, struct item *following) {
 	}
 
 	size_t i = 0;
-	for (struct item *arg = args; arg; arg = arg->next) {
-		char buf[64];
-		(void) snprintf (buf, sizeof buf, "%zu", i++);
-		if (!set (ctx, buf, arg))
+	for (struct item *arg = args; arg; arg = arg->next)
+		if (!set_arg (ctx, i++, arg))
 			return false;
-	}
 	item_free_list (args);
 	return true;
 }
@@ -822,6 +826,15 @@ execute_statement
 		body = get (ctx, name);
 	}
 
+	// XXX: not sure whether it makes more sense to evaluate a list
+	//   instead of leaving it as it is -> probably evaluate, since then
+	//   lambdas will be better: { arg _n; print @_n } 'hello\n'
+	//
+	//   Even though it's practically useless being able to dereference
+	//   function names directly that way: `@list 1 2 3` vs `list 1 2 3`
+	//
+	//   Maybe something like (choose [@f1 @f2 @f3]) arg1 arg2 arg3
+
 	if (!body) {
 		struct native_fn *fn = native_find (name);
 		if (!fn)
@@ -935,14 +948,10 @@ defn (fn_for) {
 		return set_error (ctx, "second argument must be a function");
 
 	(void) result;
-	for (struct item *iter = list->head; iter; iter = iter->next) {
-		struct item *copy;
-		if (!check (ctx, (copy = new_clone (iter))))
-			return false;
-
+	for (struct item *v = list->head; v; v = v->next) {
 		struct item *res = NULL;
-		// FIXME: wrong thing is executed, see fn_map
-		bool ok = execute_statement (ctx, body, &res);
+		bool ok = set_arg (ctx, 0, v)
+			&& execute (ctx, body->head, &res);
 		item_free_list (res);
 		if (!ok)
 			return false;
@@ -959,14 +968,12 @@ defn (fn_map) {
 
 	struct item *res = NULL, **out = &res;
 	for (struct item *v = values->head; v; v = v->next) {
-		// FIXME: wrong thing is executed
-		//   -> either temporarily append the value to the body
-		//   -> or modify execute_statement()
-		if (!execute_statement (ctx, v, out)) {
+		if (!set_arg (ctx, 0, v)
+		 || !execute (ctx, body->head, out)) {
 			item_free_list (res);
 			return false;
 		}
-		while (*out && (*out)->next)
+		while (*out)
 			out = &(*out)->next;
 	}
 	return check (ctx, (*result = new_list (res)));
@@ -981,14 +988,14 @@ defn (fn_filter) {
 
 	struct item *res = NULL, **out = &res;
 	for (struct item *v = values->head; v; v = v->next) {
-		struct item *res = NULL;
-		// FIXME: wrong thing is executed, see fn_map
-		if (!execute_statement (ctx, body, &res)) {
+		struct item *keep = NULL;
+		if (!set_arg (ctx, 0, v)
+		 || !execute (ctx, body->head, &keep)) {
 			item_free_list (res);
 			return false;
 		}
-		bool match = truthy (res);
-		item_free_list (res);
+		bool match = truthy (keep);
+		item_free_list (keep);
 		if (!match)
 			continue;
 
diff --git a/greet.ell b/greet.ell
index bd29d93..b53f21d 100644
--- a/greet.ell
+++ b/greet.ell
@@ -2,5 +2,10 @@ set greet {
 	arg _name
 	print 'hello ' @_name '\n'
 }
-greet world
-greet creator
+for (map { arg _x; .. @_x ! } [
+	world
+	creator
+]) {
+	arg _whom
+	greet @_whom
+}
-- 
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