CHANGELOG.md

[0.2.21] - 2022-04-24

• Dependencies updates, minor changes

Changed

• File .rubocop.yml Incorporating new Rubocop cops (up to version 1.28)
• File grammar.rb: Refactoring of a rule with grouping parentheses
• File s_expr_builder Change to relfect changes in grammar
• File skeem.gempsec Updated dependencies; minimal Ruby version is now 2.6+

[0.2.20] - 2021-11-01

• Code update to cope with changes in Rley v. 0.8.08

• File s_expr_builder.rb: Refactoring to cope with ? quantifier changes

• File skeem.gemspec dependency updated for Rley v. 0.8.08

[0.2.19] - 2021-08-30

• Grammar refactoring: use ?, * and + modifiers in Rley 0.8.03 rules

Changed

• File grammar.rb: Remove redundant rules after introduction of ?, * and + modifiers
• Class SkmBuilder: Removal of useless methods after removal of their rule counterpart

[0.2.18] - 2021-08-29

• Minor refactoring for Rley 0.8.03
• Code restyling to please rubocop 1.19.1.

Changed

• File .rubocop.yml updated with newer Rubocop cops
• File grammar.rb: Calling Rley::grammar_builder, replace LET* token by LET_STAR
• Other files changed to get rid of Rubocop offences

[0.2.17] - 2020-05-09

• Updated .rubocop.yml file.
• Code restyling to please rubocop 0.8.0.

[0.2.16] - 2019-08-18

• Code refactoring to use string frozen magic comments (as a consequence, srl_ruby runs only on Rubies 2.3 or newer).
• Code restyling to please rubocop 0.7.40.

[0.2.15] - 2019-07-02

• Added a basic command-line and console interface for Skeem interpreter.
• Added procedures: display!, newline, make-list

Added

• bin/skeem The CLI and REPL console implementation for Skeem
• bin/cubic.skm: A sample defining a procedure that computes the cube of a number.
• bin/hello-world.skm: The initiatic programming example

Changed

• File primitive_builder.rb Implementation of primitive procedures newline, make-list
• File base.skm Added implementation of newline procedure.
• File README.md vastly reorganized and introducing the new command line.

Removed

• Bundler-generated files bin/console, bin/setup

[0.2.14] - 2019-06-29

• Added derived expression do as an imperative iteration form.
• Added procedures: vector-set!

Added

• Class DoExpression for the representation of the do loop expression
• Class SkmDelayedUpdateBinding for implementation delayed updates of bindings

Changed

• File tokenizer.rb Added new keyword do
• File grammar.rb Added rules for the do expression syntax
• File primitive_builder.rb Implementation primitive procedure vector-set!
• File README.md Updated to reflect additions.

Fixed

• Method DatumDSL#to_datum now supports an SkmUndefined input argument.

[0.2.13] - 2019-06-22

• Skeem now accepts integers in hexadecimal notation
• Added procedures: char->integer, integer->char, char=?, char<?, char>?, char<=?, char>=?

Changed

• Class Tokenizer updated to recognize integer literals in hexadecimal notation.
• `DatumDSL#char(aLiteral): added conversion of char literal into SkmChar.
• File grammar.rb Added a rule to derive a simple datum from a character literal
• File primitive_builder.rb Implemented primitive procedures char->integer, integer->char, char=?, char<?, char>?, char<=?, char>=?
• File README.md Added mentions to new procedures.
• File `tokenize_spec.rb: added tests for haxadecimal integers.
• File primitive_builder_spec.rb: Added tests for new procedures.

[0.2.12] - 2019-06-19

• Skeem now supports character datatype
• Added procedures: boolean=?, char?, string, make-string, reverse

Added

• Class SkmChar
• Method SkmPair#proper? to check whether a pair/list is a proper one.

Changed

• Class Tokenizer updated to recognize character literals (specified by name, by hexadecimal code, escaped).
• File grammar.rb Added new terminal CHAR and one derivation rule
• File primitive_builder.rb Implemented primitive procedures boolean=?, char?, string, make-string, reverse
• File README.md Added mentions to new procedures.
• File tokenize_spec.rbDRYing the spec file.`
• File primitive_builder_spec.rb: Added tests for new procedures.

[0.2.11] - 2019-06-16

• Added procedures: gcd, lcm, numerator, denominator, floor, ceiling, truncate, round.

Changed

• File interpreter_spec.rb: Refactoring by DRYing code
• File primitive_builder_spec.rb: Refactoring by DRYing code
• File base.skm added implementation of truncate
• File primitive_builder.rb Implemented primitive procedures gcd, lcm, numerator, denominator, floor, ceiling, round.
• File README.md Added mentions to new procedures.

[0.2.10] - 2019-06-15

• Skeem now supports rational numbers (fractions)
• Added procedures: max, min, floor/, floor-quotient, floor-remainder, truncate/, truncate-quotient, truncate-remainder, quotient, remainder, modulo

Added

• DatumDSL#rational conversion method

Changed

• `DatumDSL#to_datum(aLiteral): added conversion of literal rational into rational value.
• Class Tokenizer updated to recognize rational numbers.
• File grammar.rb Added new terminal RATIONAL and rule deriving number from rational
• File primitive_builder.rb Implemented primitive procedures floor/ and truncate/
• Class SkmInteger now inherits from SkmRational class
• File base.skm added implementation of floor-quotient, floor-remainder, truncate-quotient, truncate-remainder, quotient, remainder, modulo
• Test suite file base_tests.scm expanded.
• File README.md Added mentions to new procedures.

Fixed

• File primitive_builder.rb Fixed and extended implementation of /procedure

[0.2.09] - 2019-06-10

• New procedures: complex?, exact-integer?
• Support for #| ... |# block comments (including nesting)

Added

• File base.skm: Added integer number predicate exact-integer?
• File primitive_builder.rb: Added numeric type predicate complex?
• New method Tokenizer#skip_block_comment to handle "| ... |#" comments (including their nesting)
• New folder test_skeem containing a test suite in Skeem

Changed

• Method 'PrimitiveProcedure#do_call' whenever possible, the arguments are evaluated before executing the primitive.
• File primitive_builder.rb: Lambda expression refactoring as most argument evaluations became redundant.
• Method Tokenizer#_next_token numeric literals with only zero(es) in their fractional part are implicitly converted to integers 3.0 => 3
• Method Tokenizer#skip_whitespaces refactoring & detection of block comments

Fixed

• File base.skm: predicate positive? returned #t when argument was zero. Now: (positive? 0) returns #f as expected.

Removed

• Empty method PrimitiveBuilder#add_binding removed.

[0.2.08] - 2019-06-02

• New standard procedures implemented: assq, assv

Added

• File primitive_builder.rb. New methods for implementing assq, assv

Changed

• File README.md Added mentions to new procedures.

Removed

• Superseded class SkmList removed.

[0.2.07] - 2019-05-31

• New standard procedures implemented: list-copy, procedure?, apply and map

Added

• File primitive_builder.rb. New methods for implementing list-copy, procedure?, apply and map

Changed

• File README.md Added mentions to new procedures.

[0.2.06] - 2019-05-30

• NEW Special cond (= condional) form implemented. Supports else alternative and arrow (=>) syntax.
• FIX Corner case in procedure append.

Added

• Class SkmConditional. Internal representation of condforms.

Changed

• Class Skeem::Tokenizer. Added keywords cond, else and => separator.
• Method Tokenizer#_next_token updated to accept new keywords and arrows =>
• File grammar.rb: Added new terminals and new production rules for parsing the cond form
• File s_expr_builder.rb: Added new methods for building parse tree of cond forms
• File interpreter_spec.rb: Added tests for condform.
• File README.md Updated for cond form. Added fifth example illustrating the cond form.

Fixed

• Method Primitive#create_append: test case (append '() 'a)) failed to return a (as identifier)

[0.2.05] - 2019-05-26

• Passing more standard Scheme tests, append procedure implemented.

Added

• File primitive_builder.rb: Added implementation for standard procedure append.
• Class LambdaRep: represents a parse tree of a lambda expression.

Changed

• File grammar.rb: Changed a grammar rule for (begin ...) expression because R7RS was too restrictive compared to main implementations.
• Class SkmBuilder several method updates (e.g. reduce_alt_definition)

Removed

• Class Environment superseded by class SkmFrame

[0.2.04] - 2019-04-29

• Support for local definitions [initial]

Changed

• File grammar.rb Added one production rule for third begin form syntax.
• Method SkmBuilder#reduce_begin_cmd added to implement semantic action for new begin... production rule.
• File README.md Added a couple of links for additional Scheme resources.

Removed

• Method SkmLambda#evaluate_defs replaced by homonymous method in SkmProcedureExec class.

[0.2.03] - 2019-04-26

Changed

• File README.md added new example with procedures holding each their local states.

Fixed

• The nesting of a lambda expression nested in a let construct caused an aliasing of the bindings.

[0.2.02] - 2019-04-20

Added

• Skeem now supports 'let*' local binding construct

[0.2.01] - 2019-04-19

Added

• Skeem now supports 'let' local binding construct

[0.2.00] - 2019-04-14

Major refactoring

[0.1.03] - 2019-01-15

Added

• File base.skm implementation of list procedures: caar, cadr, cdar, cddr

Changed

• File interpreter_spec.rb added spec examples to test the new procedures.
• File README.md added allusion to new procedures?

[0.1.02] - 2019-01-13

Added

• File primitive_builder.rb implementation of: equal?, make-vector, symbol->string procedures.

Changed

• File .travis.yml Added newer Ruby versions and more environments in "Allowed failures" because of Bundler issue.
• File README.md updated to reflect currently implemented features.
• Class SkmUndefined uses now the Singleton pattern.

Fixed

• File skeem.gemspec Make dependency on Bundler gem depends on the Ruby version.
• Method SkmElement#eqv? was missing. Method is now implemented.
• Class PrimitiveProcedure was unable to cope with procedures with a bounded range of arity.

[0.1.01] - 2019-01-01

• Fixes, added 'set-car!', 'set-cdr!' standard Scheme procedures.

Added

• File primitive_builder.rb implementation of: set-car!, set-cdr! list procedures.

Changed

• Methods SkmBuilder#reduce_quotation_short, SkmBuilder#reduce_quotation added optimization for quoted literal data.

[0.1.00] - 2018-12-28

• Version bumped because lists are re-implemented in a way to closer to historical Scheme/Lisp.
• A lot of internal refactoring after list re-implementation...

Added

• File primitive_builder.rb implementation of: pair?, car, cdr, cons, list->vectors list procedures.
• File primitive_builder.rb implementation of: vector->list vector procedures.

Changed

• Class SkmList is now deprecated and being replaced by SkmPairnodes.
• Class SkmElementVisitor supports new visit events: visit_empty_list and visit_pair

[0.0.28] - 2018-12-10

• Nasty bug fix: interpreter was'nt able to retrieve data argument deep in call stack.

Added

• Method Environment#inspect

Fixed

• Method SkmDefinition#call now accepts variable references that refer to a lambda or a primitive procedure.
• Method SkmLambda#evaluate_sequence failed when argument value came from a caller deep in call stack?
• Added a specific test in interpreter_spec.rb

[0.0.27] - 2018-11-25

Fixed

• The interpreter failed with second-order lambdas (lambda expression that contains another lambda)
• Added a specific test in interpreter_spec.rb

[0.0.26] - 2018-11-25

Added

• Procedure eqv?
• Procedure assert
• Class Runtime, call stack added.
• Class ProcedureCall, attribute call_site added. It contains the location of the call (line and column)

Changed

• File primitive_builder.rb implementation of: not procedure removed, not is now implemented in base.skm.
• Method Tokenizer#build_token updated to remain compatible with new Rley (> 0.7.x))

Removed

• File stoken.rb: Class SkmToken is no more necessary.

[0.0.25] - 2018-11-11

Aliasing of procedures with 'set!' is supported.

Added

• Procedures string=?, symbol=?

[0.0.24] - 2018-11-08

Many internal refactoring, augmented spec files base, initial quasiquotation implementation.

Added

• File primitive_builder.rb implementation of standard: string->length
• File datum_dsl.rb to implement an internal DSL for building literal data elements.
• Files tokenizer.rb, grammar.rb, class SExprBuilder Added support for quasiquotation: (quasiquote foo) or `foo and unquoting

Changed

• File README.md udpated to reflect currently implemented features.

[0.0.23] - 2018-10-24

Added

• File primitive_builder.rb implementation of: standard or, string->symbol, number->string, string-append procedures.

Changed

• File README.md udpated to reflect currently implemented features.

Fixed

• Method Convertible#to_skm Now converts String argument into SkmString and raises an exception when unable to convert.

[0.0.22] - 2018-10-23

Added

• Class SkmBuilderadded support for list datum.
• File primitive_builder.rb implementation of: standard and procedure.

Fixed

• File interpreter_spec.rb Added test example of list quotation.

[0.0.21] - 2018-10-22

Added

• Added support for alternative define syntax.
• File primitive_builder.rb implementation of: standard vector-ref procedure.
• Added SkmQuotation#inspect, SkmVector#inspect method

Changed

• File README.md added sub-section with links for Scheme language.

Fixed

• Method Convertible#to_skm now returns a SkmElement-like object without attempting a convertion.

[0.0.20] - 2018-10-21

Added

• Added support for quotation: (quote foo) or 'foo
• Added support for vectors #( 1 2 3 "foo")
• Added primitive procedures vector?, vector, vector-length

Changed

• File README.md enhanced with detailed implementation status.
• Class PrimitiveBuilder in addition to new Skeem procedures, the class was vastly refactored.
• Class Tokenizer extended to cope with quotation and vectors.

[0.0.19] - 2018-10-15

Added primitive procedures list?, null?, length

Added

• File primitive_builder.rb implementation of: list?, null?, length procedures.
• File primitive_builder_spec.rb spec examples for: list?, null?, length procedures.

Fixed

• Method SkmLambda#bind_locals Fix: a variadic procedure with no argument provided, should have empty list as actual argument.
• File interpreter_spec.rb Added test case for calling list procedure without argument.

[0.0.18] - 2018-10-14

Reworked procedure argument-passing.

Added

• Classes SkmArity, SkmFormals implement the core argument counting checks.

Changed

• Class PrimitiveProcedure vastly reworked to support Scheme's argument passing convention.
• Class PrimitiveBuilder primitive procedures now check the number of arguments.
• Class SkmLambda vastly reworked to support Scheme's argument passing convention.

Fixed

• Method Tokenizer#skip_whitespaces Fix: comment lines were ignored in line counting.
• Method Tokenizer#_next_token Fix: mistake in regex for period (dot) recognition.

[0.0.17] - 2018-10-06

• Fix: now support calls of anonymous lambda procedures.

Fixed

• Method SkmProcedureCall#evaluate Fix: no procedure name lookup for anonymous ones!

[0.0.16] - 2018-10-06

• Added built-in procedures odd?, even?, square, and floor-remainder (modulo).
• Supports procedures without argument.
• Implements second syntax form for variable definition.
• Fixed nasty bug when same variable name used in nested procedure calls.

Added

• Method `Environment#depth to count the nesting levels
• File primitive_builder.rb implementation of: odd?, even?, square, floor-remainder, modulo procedures.
• File grammar.rb rule for second syntax form for variable definition.
• File grammar.rb rule for calling procedures without argument.

Fixed

• Method SkmDefinition#evaluate Infinite recursion when a variable, say x, referred to a variable with same name in outer scope.

[0.0.15] - 2018-09-30

Recursive functions are now supported.
Interpreter pre-loads a Scheme file with standard procedures (zero?, positive?, negative?, abs)

Added

• File base.skm with standard Scheme procedures zero?, positive?, negative?, abs

Changed

• Class Interpreter#initialize now execute a Scheme file containing a number of standard procedures.
• File README.md Added third demo snippet showing example of recursive lambda function.

Fixed

• Method SkmLambda#bind_locals now execute any procedure call in argument list before executing the lambda itself.

[0.0.14] - 2018-09-23

Added lambda (anonymous function). This is an initial implementation that doesn't support recursion yet.

Added

• Class SkmLambda for representing a specific definition.

Changed

• Class Environment. Now supports the nesting of environments. If an environment doesn't find a variable, then it forwards the serach to the outer environment.
• File grammar.rb Added syntax rules for lambda expression.
• Class Runtime added methods nest and unnest that adds or removes an nested environment.
• Class SkmBuilder. Added method to implement the semantic action for lambda expressions.
• Class Tokenizer Added keyword lambda
• File README.md Added demo snippet with example of lambda expression.
• Files *_spec.rb Added more tests. Skeem passes the 100 'RSpec examples' mark.

[0.0.13] - 2018-09-18

Added primitive if (conditional form)

Added

• Class SkmCondition for representing a specific conditional.

Changed

• File grammar.rb Added syntax rules for conditional expression.
• Class SkmBuilder. Added method to implement the semantic action for if.
• File interpreter_spec.rb added tests for if.
• File README.md Changed demo snippet with example of conditional expression.

[0.0.12] - 2018-09-17

Added primitive define and variable reference

Added

• Class SkmDefinition for representing a specific definition.
• Class SkmVariableReference for representing a variable reference (i.e. retrieving its value)
• Module Convertible implementing utility methods for converting "native" Ruby objects into their Skeem counterpart.
• Class SkmBuilder. Added methods to implement the semantic actions for define and variable reference.
• File interpreter_spec.rb added tests for define and variable reference.

Changed

• File README.md Changed demo snippet with example of variable definition and variable reference.

[0.0.11] - 2018-09-16

Added primitive procedures: =, <, >, >=, <=

Added

• Class PrimitiveBuilder. Added methods to implement the comparison operators =, <, >, >=, <=
• File interpreter_spec.rb added tests for <, >, >=, <=

[0.0.10] - 2018-09-15

Added primitive procedures: 'boolean?', 'string?', 'symbol?', and 'not'

Added

• Class PrimitiveBuilder. Added methods to implement the predicates 'boolean?', 'string?', 'symbol?', and 'not'
• File interpreter_spec.rb added tests for 'boolean?', 'string?', 'symbol?'

Changed

• Class hierarchy SExprElement. Prefix SExpr in class names changed into 'Skm'

Fixed

• Method PrimitiveBuilder#create_minus When '-' has only one argument then it means sign change.

[0.0.9] - 2018-09-15

Added primitive procedures: 'number?', 'real?', 'integer?'.

Added

• Class PrimitiveBuilder. Added methods to implement the predicates number?, real?, integer?

Changed

• Class hierarchy SExprElement. Prefix SExpr in class names changed into 'Skm'

[0.0.8] - 2018-09-13

Added primitive operators: '-', '*', '/' operators.

Added

• Class PrimitiveBuilder. Added methods to implement the arithmetic operators - (subtraction), * (product), / (division)
• Class SExprList. Class refactoring
• Class PrimitiveFunc Internal representation of primitive functions.

Changed

• File interpreter_spec.rb Added tests for arithmetic expressions.
• File README.md Changed demo snippet with example of arithmetic expression.

[0.0.7] - 2018-09-12

Proof of concept of a primitive function: '+' operator. Demo works but code needs some polishing and testing.

Added

• Class Environment. Holds a mapping between symbol names and their associated value.
• Class PrimitiveBuilder. Builder class that seeds the default environment with primitive functions (now, limited to '+')
• Class PrimitiveFunc Internal representation of primitive functions.
• Class Runtime. Holds all context data of the Skeem interpreter.
• Methods SExprBuilder#reduce_proc_call, SExprBuilder#reduce_multiple_operands, SExprBuilder#reduce_last_operand

Changed

• Class Tokenize Added support for Scheme semi-colon comments.
• File grammar.rb Added syntax rules for procedure calling.
• File s_expr_nodes.rb Class and code refactoring.
• File README.md Changed demo snippet with example plus operator.

[0.0.6] - 2018-09-01

Initial (minimalistic) interpreter implementation.

Added

• Class Interpreter.
• Spec file interpreter_spec.rb initial test suite for the interpreter.

Changed

• File README.md Udpates, sample code snippet added, link to other similar project heist.
• Method SExprTerminalNode#interpret returns self instead of the value attribute.

[0.0.5] - 2018-08-30

Parser now generates correct parse trees for expressions consisting of a single literal.

Fixed

• ClassTokenizer The regexp for real numbers was too restricitive: it didn't recognize real numbers without fractional part.

[0.0.4] - 2018-08-29

Added

• File s_expr_nodes.rb with initial implementation of SExprTerminalNode classes.

Changed

• ClassTokenizer converts literal into Ruby "native" objects

[0.0.3] - 2018-08-25

Added

• File grammar.rb with minimalist grammar.
• Initial Parser class commit

Changed

• ClassTokenizer recognizes define keyword
• Spec file Tokenizer_spec.rb expanded with more tests.

[0.0.2] - 2018-08-25

Changed

• ClassTokenizer improved, does recognize delimiters, booleans, integers, real numbers, strings, and identifiers.
• Spec file Tokenizer_spec.rb expanded with more tests.

[0.0.1] - 2018-08-25

Added

• Initial Tokenizer class commit

[0.0.0] - 2018-08-24

Added

• Initial Github commit

Unreleased

Added

Changed

Deprecated

Removed

Fixed

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