#2716: tuple optimization

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

@@ -57,10 +57,17 @@
         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 checking i.
+  # i must be less than length and greater or equal 0.
+  # This is faster than at.
+  [i] > at-without-checks
+    i > idx!
+    if. > @
+      i.lt head.length
+      ^.head.at-without-checks i
+      ^.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 +172,22 @@
     a.at 0
     3
 
+# Test
+[] > at-without-checks-with-first-element
+  eq. > @
+    at.
+      * 100 101 102
+      0
+    100
+
+# Test
+[] > at-without-checks-with-last-element
+  eq. > @
+    at.
+      * 100 101 102
+      2
+    102
+
 # Test.
 [] > tuple-empty-fluent-with-indented-keyword
   tuple