Review Proc methods; fix dead requires

- Deprecate Proc#compose and Proc#* (use Proc#<< for composition, Ruby 2.6+)
- Update Proc#update comment noting Observable is now a gem
- Fix dead requires for removed kernel/singleton_class in Proc and Kernel
- Remove dead requires for kernel/p and kernel/__dir__ from kernel.rb

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: trans

HISTORY.md

@@ -89,6 +89,8 @@ Changes:
   * Redefine `Comparable#bound` as alias for `clamp`.
   * Add `Dir.find` as convenience wrapper around Ruby's `Find.find`.
   * Deprecate `Dir.recurse` / `Dir.ls_r` (use `Dir.find` or `Find.find` instead).
+  * Deprecate `Proc#compose` and `Proc#*` (use `Proc#<<` for right-to-left composition, Ruby 2.6+).
+  * Fix dead requires for removed `kernel/singleton_class` in Proc and Kernel.
   * Remove misplaced `applique/file_helpers` from core (test infrastructure).
   * Drop unused `test_files` directive from gemspec. (PR#301)
 

lib/core/facets/kernel.rb

@@ -47,7 +47,6 @@
 require_relative 'kernel/object_class.rb'
 require_relative 'kernel/object_hexid.rb'
 require_relative 'kernel/object_send.rb'
-require_relative 'kernel/p.rb'
 require_relative 'kernel/presence.rb'
 require_relative 'kernel/present.rb'
 require_relative 'kernel/qua_class.rb'
@@ -56,7 +55,6 @@
 require_relative 'kernel/returning.rb'
 require_relative 'kernel/silence.rb'
 require_relative 'kernel/silence_warnings.rb'
-require_relative 'kernel/singleton_class.rb'
 require_relative 'kernel/super_method.rb'
 require_relative 'kernel/tap.rb'
 require_relative 'kernel/temporarily.rb'
@@ -69,7 +67,7 @@
 #require_relative 'kernel/y.rb'                 # uncommon
 require_relative 'kernel/yes.rb'
 require_relative 'kernel/__class__.rb'
-require_relative 'kernel/__dir__.rb'
+#require_relative 'kernel/__dir__.rb'  # removed, use Ruby's built-in __dir__
 require_relative 'kernel/__get__.rb'
 require_relative 'kernel/__set__.rb'
 

lib/core/facets/proc/bind.rb

@@ -1,5 +1,3 @@
-require 'facets/kernel/singleton_class'
-
 class Proc
 
   # Bind a Proc to an object returning a Method.

lib/core/facets/proc/compose.rb

@@ -1,42 +1,21 @@
 class Proc
 
-  # Returns a new proc that is the functional
-  # composition of two procs, in order.
-  #
-  #   a = lambda { |x| x + 4 }
-  #   b = lambda { |y| y / 2 }
-  #
-  #   a.compose(b).call(4)  #=> 6
-  #   b.compose(a).call(4)  #=> 4
-  #
-  # CREDIT: Dave
-
+  # @deprecated Use Proc#>> or Proc#<< instead (built-in since Ruby 2.6).
   def compose(g)
-    raise ArgumentError, "arity count mismatch" unless arity == g.arity
-    lambda{ |*a| self[ *g[*a] ] }
+    warn "Proc#compose is deprecated. Use Proc#<< instead (right-to-left composition).", uplevel: 1
+    self << g
   end
 
-  # Operator for Proc#compose and Integer#times_collect/of.
-  #
-  #   a = lambda { |x| x + 4 }
-  #   b = lambda { |y| y / 2 }
-  #
-  #   (a * b).call(4)  #=> 6
-  #   (b * a).call(4)  #=> 4
-  #
-  # CREDIT: Dave
-
+  # @deprecated Use Proc#>> or Proc#<< for composition (built-in since Ruby 2.6).
   def *(x)
-    if Integer===x
-      # collect times
+    warn "Proc#* is deprecated. Use Proc#<< for composition (right-to-left).", uplevel: 1
+    if Integer === x
       c = []
       x.times{|i| c << call(i)}
       c
     else
-      # compose procs
-      lambda{|*a| self[x[*a]]}
+      self << x
     end
   end
 
 end
-

lib/core/facets/proc/to_method.rb

@@ -1,5 +1,4 @@
 require 'facets/proc/bind'
-require 'facets/kernel/singleton_class'
 
 class Proc
 

lib/core/facets/proc/update.rb

@@ -1,6 +1,13 @@
 class Proc
 
-  # Use a Proc as an observable.
+  # Alias for #call, allowing a Proc to be used as an Observer.
+  #
+  # Ruby's Observable module (now the `observer` gem, removed from
+  # stdlib in Ruby 3.2) calls #update on observers. This alias
+  # lets a Proc serve as an observer directly.
+  #
+  # TODO: Consider submitting a PR to the observer gem to include
+  # this extension there instead.
   #
   # CREDIT: Tim Pease