#2716: tuple optimization

eo-runtime/src/main/eo/org/eolang/tuple.eo

@@ -57,10 +57,16 @@
         index.lt 0
         index.gte len
       error "Given index is out of tuple bounds"
-      if.
-        index.lt (len.plus -1)
-        ^.head.at index
-        ^.tail
+      at-without-checks index
+
+    # Takes element from the tuple without index validation.
+    # Here i must be an object that can be comparable with int using lt attribute.
+    [i] > at-without-checks
+      i > idx!
+      if. > @
+        idx.lt head.length
+        ^.^.head.at.at-without-checks idx
+        ^.^.tail
 
   # Create a new tuple with this element added to the end of it.
   [x] > with

eo-runtime/src/test/eo/org/eolang/tuple-tests.eo

@@ -172,6 +172,24 @@
     a.at 0
     3
 
+# Test
+[] > at-without-checks-with-first-element
+  eq. > @
+    at-without-checks.
+      at.
+        * 100 101 102
+      0
+    100
+
+# Test
+[] > at-without-checks-with-last-element
+  eq. > @
+    at-without-checks.
+      at.
+        * 100 101 102
+      2
+    102
+
 # Test.
 [] > tuple-empty-fluent-with-indented-keyword
   tuple