add sig/fibonacci.rbs

Steepfile

@@ -8,11 +8,13 @@ target :lib do
   check "lib/compsci/byte_pack.rb"
   check "lib/compsci/collatz.rb"
   check "lib/compsci/elo.rb"
+  check "lib/compsci/fibonacci.rb"
 
   # library "pathname"              # Standard libraries
   # library "strong_json"           # Gems
 
   library "zlib"
+  # library "matrix"
 
   # configure_code_diagnostics(D::Ruby.strict)
 end

lib/compsci/fibonacci.rb

@@ -27,7 +27,7 @@ def self.dynamic(n)
 
     # https://ianthehenry.com/posts/fibonacci/
     def self.matrix(n)
-      (Matrix[[1, 1], [1, 0]] ** n.pred)[0, 0]
+      (Matrix[[1, 1], [1, 0]] ** n.pred)[0, 0] # steep:ignore
     end
   end
 end

sig/fibonacci.rbs

@@ -0,0 +1,10 @@
+module CompSci
+  module Fibonacci
+    def self.classic: (Integer n) -> Integer
+    def self.cache_recursive: (Integer n, ?Hash[Integer, Integer] cache) ->
+      Integer
+    def self.cache_iterative: (Integer n) -> Integer
+    def self.dynamic: (Integer n) -> Integer
+    def self.matrix: (Integer n) -> Integer
+  end
+end