Ruby (MRI) most relevant versions.

Ruby 1.8.0  
2003-08  
  class.allocate
  first argument parentheses change
  to_str
  multiple assignment behaviour change
  many lib changes
   
Ruby 1.8.5  
2006-08  
  Non-blocking IO
  rdoc/ri changes
   
Ruby 1.8.6  
2007-03  
  Faster mutex
   
Ruby 1.8.7  
2008-06  
  Enumerator (from 1.9)
   
Ruby 1.9  
2007-12  
  new hash syntax
  new lambda syntax
  splats/mandatory arguments changes…
  block arguments are local; new semantics
  new lines before : or .
  source code encoding/magic comments
  constant definition semantics
  Enumerators
  Hash preserves order
  String encodings
  String#[] semantics, ?x
  rray#choice nitems
  to_s == inspect in Hash, etc
  Fibers
  Native Threads / GIL
  YARV
   
  String#each_line/lines, not each
  continuations moved to library
  Precision removed
   
Ruby 1.9.2  
2010-08  
  Regexp chages (\p…)
  $: no current dir; use require_relative
  Float#rationalize INFINITY NAN
   
Ruby 1.9.3  
2011-10  
  Regexp changes
   
  libs/internal
   
Ruby 2.0  
2013-02  
  keyword arguments
  refinements (experimental)
  %i %I symbol arrays
  UTF-8 default encoding
  lazy enumeration
   
Ruby 2.1  
2013-12 semantic versioning from now on; 2.1.x vs 1.9.3-px
  refinements
  frozen string literals
  r,i numeric suffixes
  def returns name as symbol
  required keyword arguments (without default value)
   
  RGenGC (generational GC)
   
Ruby 2.2  
2014-12-25  
  Incremental GC, Symbol GC
  Float#next_float, prev_float
  Enumerable#slice_after
  File.birthtime

Numerical features availability

  • Float#round with precision argument 1.9
  • Rational with 0 denominator raises ZeroDivisionError since 1.9.1 1
  • Float#to_r 1.9.1 1
  • Float#rationalize 1.9.2
  • Float::NAN, INFINITY : 1.9.2
  • Float(hex-string) / printf %a %A : 1.9.2
  • BigDecimal constructor from Integer, Float+precision, Rational+precision: 1.9.3
  • BigMath module functions (rather that needing to include BigMath…): 1.9.3
  • bigdecimal/util #to_d 1.9.3
  • Float#next_float Ruby 2.2
  • Float#prev_float Ruby 2.2

  1. Internal version 1.9.0-2 actually, when Rational was moved from stdlib (Ruby) into core (C) ↩ ↩2