Added some more datetime stdlib Fun with examples. And some permission fixes. (0.36.1)

lib/utils/datetime.fun

@@ -1,3 +1,12 @@
+/*
+ * This file is part of the Fun programming language.
+ * https://fun-lang.xyz/
+ *
+ * Copyright 2025 Johannes Findeisen <you@hanez.org>
+ * Licensed under the terms of the Apache-2.0 license.
+ * https://opensource.org/license/apache-2-0
+ */
+
 // Date/time utilities abstraction for the Fun stdlib.
 // Minimal version to validate syntax.
 
@@ -30,3 +39,66 @@ class DateTime()
   fun iso_now(this)
     ms = time_now_ms()
     return date_format(ms, "%Y-%m-%dT%H:%M:%S")
+
+  // Seconds since Unix epoch (integer)
+  fun now_s(this)
+    return to_number(time_now_ms() / 1000)
+
+  // Convert milliseconds to seconds (floor)
+  fun ms_to_s(this, ms)
+    return to_number(to_number(ms) / 1000)
+
+  // Convert seconds to milliseconds
+  fun s_to_ms(this, s)
+    return to_number(to_number(s) * 1000)
+
+  // Add milliseconds to an epoch-ms timestamp
+  fun add_ms(this, ms, delta_ms)
+    return to_number(to_number(ms) + to_number(delta_ms))
+
+  // Add seconds to an epoch-ms timestamp
+  fun add_seconds(this, ms, seconds)
+    return this.add_ms(ms, this.s_to_ms(seconds))
+
+  // Difference in milliseconds: b - a
+  fun diff_ms(this, a_ms, b_ms)
+    return to_number(to_number(b_ms) - to_number(a_ms))
+
+  // Milliseconds elapsed since given epoch-ms timestamp
+  fun since_ms(this, past_ms)
+    return this.diff_ms(past_ms, this.now_ms())
+
+  // Format an arbitrary epoch-ms timestamp as ISO local
+  fun iso_from(this, ms)
+    return date_format(to_number(ms), "%Y-%m-%dT%H:%M:%S")
+
+  // Date-only string for a timestamp (YYYY-MM-DD)
+  fun date_str(this, ms)
+    return date_format(to_number(ms), "%Y-%m-%d")
+
+  // Time-only string for a timestamp (HH:MM:SS)
+  fun time_str(this, ms)
+    return date_format(to_number(ms), "%H:%M:%S")
+
+  // Today's date as YYYY-MM-DD
+  fun today_str(this)
+    return this.date_str(this.now_ms())
+
+  // Start a monotonic timer
+  fun start_timer(this)
+    return clock_mono_ms()
+
+  // Elapsed ms from a monotonic start value
+  fun elapsed_ms(this, start_mono_ms)
+    return to_number(clock_mono_ms() - to_number(start_mono_ms))
+
+  // Sleep for the given milliseconds (non-negative)
+  fun sleep_ms(this, ms)
+    m = to_number(ms)
+    if m > 0
+      sleep(m)
+    return m
+
+  // Sleep for the given seconds
+  fun sleep_s(this, s)
+    return this.sleep_ms(this.s_to_ms(s))