v7.2

  * added derivation->pict

  * brought the letrec model up to date with modern Racket

  * misc minor bug fixes and documentation improvements

v7.1

  * added make-immutable-binding-hash and make-binding-hash

  * various bug fixes

v7.0

  * various bug fixes

v6.12

  * typeset prime characters better, e.g. when writing e_′,
    don't use the subscript style for the ′ character

  * various bug fixes

v6.11

  * various bug fixes

  * added #:codomain clause to `reduction-relation`

v6.10

  * added a two argument version of `alpha-equivalent?`

  * added `sc-linebreaks`

  * use the atomic rewriters when rendering a 
    metafunction's name in its type signature

  * added judgment-form-show-rule-names

  * improved the binding-forms documentation

  * misc bug fixes

v6.9

  * add mf-apply

  * improve define-relation's cooperation with judgment-holds and
    related constructs

  * various bug fixes

v6.8

  * improved the ambiguity checker

  * minor bug fixes

v6.7

  * performance improvements

  * minor bug fixes

v6.6

  * added test-judgment-holds

  * bug fixes and performance improvements

v6.5

  * bug fixes

v6.4

  * add support for variable binding declarations in define-language
    and have pattern match now preserve alpha equivalence, based on
    those declarations.

    This improvement is based on the ideas in Paul Stansifer's
    dissertation and is implemented by Paul Stansifer.

  * changed shortcuts in --> so that non-terminals are no
    longer allowed for the names in the shortcut "parameters"

    These shortcut names were never constrained to actually be
    non-terminals, so this change is intended entirely to be
    able to give a helpful error message in an attempt to avoid
    confusion

v6.3

  * Add new syntax error checking that ensures that each pattern
    generates either exactly one hole or zero holes.

  * Add a number of new parameters for finer-grained control of
    rendering.

  * Added a new, in-depth tutorial and some extended exercises

  * Added the #:all? argument to apply-reduction-relation*

  * check-metafunction and check-reduction-relation (and redex-check
    with the #:source keyword) no longer check the "extras" clauses
    and instead just blindly generate from the left-hand side
    patterns. (This speeds up compilation of Redex programs that use
    define-metafunction and reduction-relation.)

  * Judgment forms that have the mode (I O) can be used as
    reduction-relations

  * misc bug fixes

v6.2

  * Performance improvements for example generation, both for 
    enumerators (#:i-th in generate-term) and judgment forms
    (#:satisfying in generate-term)

  * Add short discussion of each of the benchmark programs

  * Use unicode whitebracket characters for metafunction typesetting

  * add support for "big left curly bracket"-style conditionals
    when typesetting metafunctions

v6.1

  * changed the semantics for _!_ variables when they are under
    ellipses, making them less insane. There is now a much simpler
    description of how these two interact (in the docs)
    
  * improved the performance of term generation from judgment-forms
    (when using the #:satisfying keyword argument)

  * lots of improvements to the enumeration test case generator

  * metafunctions can now typeset their contracts

  * added #:equiv option to test-equal

  * added default-equiv

  * added the #:enum-p keyword
    (based on statistics help from Neil Toronto)

  * change the default strategy of redex-check to do enumeration first,
    then interleave random generation and enumeration and then just
    do random generation

v6.0

  * Added an enumerator for patterns. For example, here's how to get
    the first 100 untyped LC terms (over 3 variables) and the 10^10000-th:

        #lang racket
        (require redex)
        
        (define-language L
          (e (e e) x (λ (x) e))
          (x a b c))
        
        (for/list ([i (in-range 100)])
          (generate-term L e #:i-th i))

        (generate-term L e #:i-th (expt 10 10000))

    Thanks to Max New for the enumerator.

  * More patterns that match no terms are now syntax errors, e.g.:
    (any_1 ..._!_1 any_2 ..._!_1 (any_1 any_2) ...)
 
  * added where-make-prefix-pict and where-combine parameters.

  * added #:keep-going to redex-check

  * added #:satisfying to redex-check

  * added #:reduce argument to traces

  * DrRacket's Check Syntax now works better with Redex pattern variables

  * The pattern _ now matches anything but does not bind a variable

  * bug fixes

v5.3.4

  * adjusted define-union-language to allow the unioned languages to
    have overlapping non-terminals; in that case the productions are
    combined

  * Adjust check-metafunction and check-reduction-relation so that
    they skip over randomly generated terms that don't match the
    contract spec (or #:domain spec). This means that when there is a
    case in the metafunction (or reduction-relation) whose nominal
    pattern is more general than the contract would allow, that those
    terms are discarded instead of used as inputs to the predicate.

  * Added the #:pre keyword to define-metafunction. It allows
    contracts that have to relate different arguments to a
    metafunction.

  * Fixed the way random generation for define-judgment-form works so
    that it properly handles metafunctions (i.e., it properly takes
    into account that previous patterns in a metafunction must not
    match when generating a particular clause)


v5.3.3

No changes

v5.3.2

  * added random-generation based on define-judgment-form
    (which allows Redex to more effectively generate things
     like well-typed terms)

  * removed the restriction on unquotes in define-judgment-form

  * added the option to use judgment-forms with only I mode
    positions in terms

  * added 'boolean' as a new pattern

  * define-relation now compiles to judgment-form
    (instead of a metafunction)
  
  * added show-derivations to visualize judgment form derivations
    	     
v5.3.1

  * added optional #:lang keyword to term

  * added the ability to name clauses to define-judgment-form

  * added judgment-form-cases

  * adjust define-judgment-form typesetting so that it uses
    the line breaks in a premise to determine how to line
    break the typeset version

v5.3

  * added the amb tutorial.

  * added define-union-language

  * added define-extended-judgment-form

  * extended render-* functions so they can produce PDF

v5.2.1

  * rewrote the internals of the pattern matcher to be more consistent
    (centralized more error checking, moving more of it to compile
    time, and various other internal cleanups).

  * improved the way caching works so it uses about 1/5th memory and
    speeds up the R6RS test suite by about a factor of 2.

  * added a number of optimizations to the pattern matcher that
    speed up the R6RS test suite by 50% or so and speed up a
    lambdaJS benchmark by about a factor of 25.

  * added support for side-conditions and where clauses to
    define-relation, also added support for side-conditions to
    define-judgment-form

  * added the List-machine benchmark (by Appel, Dockins & Leroy)

v5.2

  * added define-judgment-form form

  * added define-term form

  * added with-compound-rewriters form

  * added Ariola-Felleisen by-need evaluation contexts to examples

  * improved error message for definition forms in expression contexts

v5.1.2

  * added support for typsetting define-relation relations

  * made apply-reduction-relation* call remove-duplicates
    on the result of apply-reduction-relation

  * extended render-reduction-relation-rules to accept rule indices
    in addition to rule names

  * added the to-lw/stx procedure

  * fixed domain checking for unioned reduction relations

  * added the #:cache-all? argument to apply-reduction-relation*
    and the current-cache-all? parameter

  * fixed stepper's handling of symbols that required || quoting

  * removed all undocumented exports

  * added the redex-let form

  * added the #:source argument to generate-term

  * changed redex-match to hide bindings for named ellipses such
    as ..._x

  * improve test-->E failure message

  * fixed misc. bugs in examples and typos in documentation

v5.1.1

  * changed pattern language to disallow unquote

  * fixed matching of ..._x and ..._!_x within ellipses

  * fixed bugs in stepper's diff highlighting

  * improved rendering of arrows in typesetting

  * added support for unioned metafunction codomains

  * fixed typesetting of the pattern (hole p_0 p_1 ...)

  * added arrow->pict, which shows how reduction relation are rendered
    in typesetting

  * added a parameter that provides the default for redex-check's
    #:attempts argument

  * changed the random term generator to produce shorter sequences

  * added a Redex model of the system in Jay McCarthy's ICFP '09 paper
    "Automatically RESTful Web Applications Or, Marking Modular
    Serializable Continuations" to the examples directory

  * resolved PRs 10665, 11174, 11579, 11041, 10837, and 11853

v5.1

  * adds an optional #:pred keyword argument to `test-->>' form

  * added the `redex-pseudo-random-generator' parameter

  * added option `::=' syntax to non-terminal definitions

  * added contract support to `define-relation'

  * added the `test-->∃' form

  * fixed minor bugs

v5.0.2

  * added `pretty-print-parameters' to control term pretty-printing

  * added `grammar-style' and `paren-style' typesetting parameters

  * added support for computed reduction rule names

  * added delimited control model to examples

  * added optional #:attempt-size and #:prepare keyword arguments to random 
    testing forms

  * fixed minor bugs

v5.0.1

  * changed the matching of `where' clauses in a
    backwards-incompatible way. Previously, pattern variables bound by
    a `where' left-hand side shadowed bindings from earlier clauses
    and the case's left-hand side; now, `where' clauses match only
    when their bindings match the existing ones. 

  * fixed minor bugs

v5.0

  * added an optional term-equivalence predicate to the test--> and
    test-->> forms

  * added R6RS and Racket VM models to examples sub-collection

  * fixed minor bugs
  
v4.2.5

  * reversed the order in which `where' and `side-condition' clauses
    appear in typeset definitions

  * added support for `where' and `side-condition' clauses that do not
    appear in the metafunction's typeset definition

  * added a #:print? flag to redex-check, to control whether it prints
    or returns its result

  * renamed the #:attempts keyword to #:attempt-num in the `generate-term' form

  * changed typesetting to render `where' clauses as `fresh' clauses
    when the right-hand side is a call to `variable-not-in' or 
    `variables-not-in'

  * changed typesetting of meta-variables to render anything following
    a caret (^) as a superscript

  * minor bug fixes

v4.2.4

  * minor bug fixes

v4.2.3

  * added support for collecting metafunction coverage, using the
    'relation-coverage' parameter. This includes a backwards
    incompatible change: the parameter's value is now a list of
    coverage structures, to allow coverage collection for multiple 
    metafunctions and reduction relations at once.

  * redex/reduction-semantics exports the names `hole' and `in-hole'
    (and `term' no longer captures those names).

  * minor bug fixes

v4.2.2

  * minor bug fixes

v4.2.1

  * improved 'where' conditions in metafunctions and
    reduction-relations so that they work with Redex's full pattern
    language. 

    This is a backwards incompatible change. In old versions,
    variables used in a where clause were independent of the pattern
    language. Now, if the variable in a where clause is a literal in
    the grammar, the result of the where clause must be that
    literal. Similarly, if the variable is a non-terminal, the result
    must match that non-terminal.

  * added 'define-relation' 

  * relaxed the restrictions on metafunctions so that multiple
    pattern matches are allowed, as long as the right-hand side
    has the same value for each different pattern binding

  * added metafunction styles 'up-down/compact-side-conditions,
    'left-right/compact-side-conditions, and 
    'left-right/beside-side-conditions.

  * added #:x-spacing and #:y-spacing parameters to traces and
    traces/ps

  * changed the grammar for 'side-condition' clauses
    from (side-condition scheme-expression ... )
    to (side-condition scheme-expression)

v4.2

  * minor bug fixes

v4.1.5

  * renamed test--> to test-->>

  * added a new test--> that only tests for a single step in the
    reduction sequence

  * added #:cycles-ok flag to (what is now called) test-->>

  * define-metafunction and reduction-relation now work better with
    Check Syntax
    
  * added the #:arrow keyword to reduction-relation, which lets you use
    a different main arrow (mostly useful for the typesetting)

  * added domain specifications to reduction relations via
    the #:domain keyword

  * 'traces' copes better with errors during reduction 

  * initial-char-width now accepts functions to give finer grained
    control of the initial widths of the terms.

  * traces & traces/ps: added the ability to specify a mixin
    to be mixed into the graph pasteboard

  * added built-in patterns natural, integer, and real
  
v4.1.4

  * added redex-check, a tool for automatically generating test cases
    for Redex specifications.

  * improved traces for use in generating PostScript:

    - added traces/ps

    - added more coloring arguments to traces: #:scheme-colors? 
    #:default-arrow-highlight-color, and #:default-arrow-color

    - added the #:layout argument to traces 

    - added term-node-set-position! and related term-node functions

  * Added tracing to metafunctions (see current-traced-metafunctions)

  * added caching-enabled? parameter (changed how set-cache-size! 
    works)

v4.1.2

  - added white-bracket-sizing to control how the brackets
    are typeset when rendering a metafunction.

  - added render-* functions that make it easier to experiment
    with typesetting at the REPL.

  - where clauses in metafunctions now are implicitly in
    `term's (they were not documented at all before)

v4.1 (this is the first version that was included in the PLT
      distribution. Before this, Redex was in PLaneT).

  EXTENSIONS:

  - added test-equal, test-pred, test-reduces, and test-results

  - removed restriction on apply-reduction-relation*
    replaced it with additional work while matching
    non-terminals to remove the redundancy

  - added `in-domain?'

  CHANGES:

  - define-metafunction and co. now use a different syntax.

  - got rid of named holes. This means, eg, that (hole #f) now matches
    a two element list, not just the hole directly.

  - zero occurrences of a hole when matching an `in-hole' now
    correctly fails.

  - the `where' keyword in reduction-relation became `with' (and the
    arguments reversed order)

  - renamed the `rib' struct to `bind' (and mismatch-rib =>
    mismatch-bind)

  - merged the various traces functions into a single
    function that accepts keyword arguments.

  - renamed the loc-wrapper struct to lw.

  - language->ps and language->pict's listof-symbols is now
    optional and thus the language->ps's arguments changed
    order to make that work.

  - renamed test-match to redex-match

  - no long export mtch struct or bindings struct and
    test-match's result is not simplified.

  - extend-reduction-relation now uses the names of the
    rules to replace existing rules (instead of just
    unioning the rules)

  - in-hole used to substitute into named holes, but now it
    only substitutes into unnamed holes. Use in-named-hole
    on the right-hand side to do the substitution

  - removed hole-here

  BUG FIXES:

  - fixed a (not easily noticed) bug in the way hole
    matching worked for named holes.

  - extending a non-terminal that's been defined together
    with other non-terminals now works as expected.

  - handling of non-terminals uses that have underscores in
    them now works properly (only showed up when using them
    in the definition of a language)

  - an extended language can now define multiple non-terminals
    together

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
below here were the versions of Redex that appeared in PLaneT
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

("robby" "redex.plt" 4 4)

  - undid some changes that broke backwards compatibility

("robby" "redex.plt" 4 3)

  - added extend-reduction-relation
  - fixed a bug whereby reduction relations that reduced to
    false were always ignored

("robby" "redex.plt" 4 2)

  - fixed a bug in the way `in-hole' inside
    an ellipsis on the right-hand side of a
    reduction rule.

("robby" "redex.plt" 4 1)

  - improved stepper so that scrolling works when large
    terms are present.

("robby" "redex.plt" 4 0)

  - changed conventions for subscripts. Now, non-terminals
    w/out subscripts bind in reduction rules (but they still
    do not bind in grammar definitions).

  - wheres and side-conditions now bind as expected in
    reduction-rules

  - fixed a bug in metafunction pict generation (parallel
    fix from 3.28)

  - renamed horizontal-arrow-space to arrow-space.
  - renamed horizontal-label-space to label-space.

("robby" "redex.plt" 3 27)

  - added horizontal-arrow-space, horizontal-label-space
  - number & variable now typeset in italics (to match the other non-terminals)
  - improved fresh variable generation
  - added `where' for bindings in metafunctions
  - added 'up-down mode for metafunction typesetting
  - added optional argument to reduction-relation->pict &
    reduction-relation->ps
  - PR 8957

("robby" "redex.plt" 3 26)

  - fixed a bug in pict generation

("robby" "redex.plt" 3 25)

  - added hole-here support for `term'

("robby" "redex.plt" 3 24)

  - added curly-quotes-for-strings and current-text

("robby" "redex.plt" 3 23)

  - fixed a bug that cause typesetting of grammars that
    defined hole as the first production of some
    non-terminal.

  - added hide-hole pattern

("robby" "redex.plt" 3 22)

  - ??

("robby" "redex.plt" 3 21)

  - added `where' as a binding form in the individual
    clauses of a reduction-relation.

  - typesetting: 

    - improved handling of nested term, quote,
      unquote, and unquote-splicing.

    - fixed up in-named-hole and (hole x) to use subscripts.

    - improved the docs for the loc wrappers to explain
      logical spacing.

    - improved typesetting of languages built with
      extend-language. See extend-language-show-union.

    - added set-arrow-pict!

("robby" "redex.plt" 3 20)

  - improved the interface for rewriting aspects of the typesetting.

  - added linebreaks, with-compound-rewriter, and with-atomic-rewriter

("robby" "redex.plt" 3 19)

  - improved source locations for error messages when misusing ellipses, eg:
    (term-let ([(x ...) '(1 2)] [(y ...) '(1 2 3)]) (term ((x y) ...)))
    or similar things via reduction-relation, metafunctions, etc.

  - fixed PR 8752: `name' patterns only show the name,
    leaving the thing defined to the where clause

("robby" "redex.plt" 3 18)

  - fixed PRS relating to pict generation: 8749 8751 8750
    and a few other bugs along the way.

("robby" "redex.plt" 3 17)

  - initial-char-width now controls both the stepper & traces

("robby" "redex.plt" 3 16)

  - added define-multi-args-metafunction
  - finished first pass of the pict generation rewriting

("robby" "redex.plt" 3 15)

  - fixed a bug in stepper/seed

("robby" "redex.plt" 3 14)

  - fixed some silly mistakes in the packaging

("robby" "redex.plt" 3 13)

  - added variable-not-otherwise-mentioned as a new pattern
  - added stepper/seed
  - added an optional pretty-printing argument to stepper.
  - improved the ps rendering of the arrows
    for --> -> => ==> ~> and ~~>
  - rewrote internals of pict rendering (hopefully no change
    yet, but there may be bugs introduced ...).

("robby" "redex.plt" 3 12)

  - Added pict and .ps generation functions for
    reduction-relations, metafunctions, and grammars. These
    are still primitive; the most obvious missing feature is
    the inability (without secret knowledge) to replace the
    pink stuff.
  - fixed a bug in the way the stepper highlights
    differences in the presence of quote (by disabling the '
    shortcuts printing)

    NOTE this version of redex requires not just any
    369.100, but one from 5/19 in the afternoon (or newer).

("robby" "redex.plt" 3 11)

  - changed the order of the arguments in the new `fresh' clauses
    introduced in the last release.

("robby" "redex.plt" 3 10)

  - fixed bugs in the way that ..._x patterns work (they 
    didn't handle binding well).
  - fixed misc bugs in the stepper
  - added the ability to generate a sequence of fresh variables
    in a single rule

("robby" "redex.plt" 3 9)

  - added side-condition specs to metafunctions
  - added test-reduces and test-reduces/multiple to schemeunit.ss
  - fixed a bug in the handling of _!_
  - improved the "found the same binder" error message to show
    the source locations of the two offending binders

("robby" "redex.plt" 3 8)

  - fixed a bug in the way (hole #f) patterns matched.
  - fixed a bug in the initial height of the boxes in `traces' 
  - added reduction->relation-names
  - added ability to step until a particular reduction (and
    the reduction labels) in the stepper.

("robby" "redex.plt" 3 7) 

  - improved syntax error message (PR 8576)
  - added difference highlighting for adjacent terms in the stepper

("robby" "redex.plt" 3 6)

  - added stepper

("robby" "redex.plt" 3 5)

  - bugfix (I think ... this version's changes seem to have been forgotten)

("robby" "redex.plt" 3 4)

  - added term-node-children

("robby" "redex.plt" 3 3)

  - added term-match and term-match/single
  - added variables-not-in
  - fixed a bug in metafunctions

("robby" "redex.plt" 3 2)

  - added language-nts
  - added better error messages when using parts of the
    pattern language as ordinary things in the grammar.

("robby" "redex.plt" 3 1) 

  - adds the ability to have multi-colored terms, not just
    pink ones.

("robby" "redex.plt" 3 0)

This release changes the syntax of the reduction relations
to make it more consistent and more in line with the way
reduction relations are written in papers. This is the
precise set of removals and additions:

  - added extend-language
  - added reduction-rule & apply-reduction-relation
  - added union-reduction-relations
  - added define-language

  - changed compatible-closure & context-closure so that the
    pattern argument is not quoted, but is just the pattern
    in the last argument.

  - changed term-node-labels so that it can return #f (in
    the list) when a reduction doesn't have a label.

  - removed language->predicate, compile-pattern,
    match-pattern (use test-match instead)

  - removed reduction, reduction/name, reduction/context,
    reduction/context/name (use reduction-relation instead)

  - removed red? (use reduction-relation? instead)

  - removed reduce (use apply-reduction-relation instead)

  - removed reduce-all (use apply-reduction-relation* insetad)

  - removed reduce/tag-with-reduction (use
    apply-reduction-relation/tag-with-names instead)

  - removed red-name, reduction->name, give-name

  - removed language (use define-language instead)

  - removed helper.ss

Other improvements:

  - check syntax draws arrows for the non-terminals in a
    `language' now, both to the language and to the
    reduction rules.

("robby" "redex.plt" 2 6)

  - added reduce-all and note about bad parsing performance
    issues.

  - added `test-match' and note about how to debug redex
    programs to doc.txt
 
  - added redex-specific 'check' functions for use with
    schemeunit.

  - add `metafunction' for defining meta functions using the
    pattern matching notation used in reductions and grammars.

("robby" "redex.plt" 2 5) 

  - fixed bugs in compatible-closure & context-closure

("robby" "redex.plt" 2 4) 

  - reduced the amount of memory used for caching
    significantly (with some small speedup for 
    a largeish reduction semantics test suite)

  - added set-cache-size!

  - added variable-prefix pattern

  - added ..._<id> pattern that can be used to ensure matching
    lengths of repeated patterns.

  - added _!_ subscripts (both in ... and regular) to ensure
    that the matched things are different (or have different
    lengths in the case of ..._!_ subscripts)

("robby" "redex.plt" 2 3) 

  - added the ability to traverse the graph generated by
    traces in order to decide if a term should be
    highlighted in red. See the traces/pred documentation
    for details.

  - added term-node functions

  - added red-name function

  - removed make-plt.ss from archive

("robby" "redex.plt" 2 2)

  - added a blurb, fixed a typo in the docs.

("robby" "redex.plt" 2 1)

  - changed the way a contract is specified on the matcher
    to get a 30% speed up on the beginner test suite.
    Thanks, Matthew for spotting that!

("robby" "redex.plt" 2 0)

  - fixed a bug in compatible-closure handling that could
    result in duplicate matches when there should only have
    been a single match.

  - added labels to edges for reductions
    when shown in GUI. See docs for
    reduction/name

  - small performance improvement to matcher 
    (10-20% on non-trivial examples)

  - added letrec.ss example (and improved some
    of the examples to use labels)

("robby" "redex.plt" 1 3)

  - Fixed a bug in the compatible closure function; otherwise the
    same as 1.1

("robby" "redex.plt" 1 2)

  - Obsolete'd version. It used to be a first attempt at the 2.0
    revision, but now should be avoided. 

    Use 2.0 instead of this version.

("robby" "redex.plt" 1 1)

  - fixed packaging error

("robby" "redex.plt" 1 0)

  - initial release to PLaneT

