Feat/add macros

[grantwforsythe]

Overview

Add (very buggy) macro system which utilizes three new key words:

1. quote - stops the evaluation of a node and returns a quote object
2. unquote - evaluate a node
3. macro - define a new macro which returns a quote object by definition

Example

>> let unless = macro(condition, consequence, alternative) {
  quote(
    if (!(unquote(condition))) {
      unquote(consequence); 
    } else { 
      unquote(alternative); 
    }
  );
}
>> unless(10 > 5, puts("10 is greater than 5"), puts("10 is not greater than 5")
"10 is greater than 5" -- notice that null is not outputted and the other puts statement is not evaluated

[codecov]

Codecov Report

Attention: Patch coverage is 58.85417% with 79 lines in your changes missing coverage. Please review.

Project coverage is 70.29%. Comparing base (11b0f13) to head (91a84de).
Report is 17 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/object/object.go	0.00%	31 Missing ⚠️
pkg/ast/ast.go	0.00%	13 Missing ⚠️
pkg/evaluator/macro_expansion.go	86.20%	5 Missing and 3 partials ⚠️
pkg/ast/modify.go	86.95%	5 Missing and 1 partial ⚠️
pkg/object/environment.go	0.00%	5 Missing ⚠️
pkg/evaluator/builtins.go	0.00%	4 Missing ⚠️
pkg/evaluator/quote_unqote.go	78.94%	2 Missing and 2 partials ⚠️
pkg/parser/parser.go	60.00%	2 Missing and 2 partials ⚠️
pkg/repl/repl.go	0.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main       #9      +/-   ##
==========================================
- Coverage   72.00%   70.29%   -1.71%     
==========================================
  Files          11       14       +3     
  Lines         925     1111     +186     
==========================================
+ Hits          666      781     +115     
- Misses        225      288      +63     
- Partials       34       42       +8     

Files with missing lines	Coverage Δ
pkg/evaluator/evaluator.go	84.95% <100.00%> (+0.94%)	⬆️
pkg/lexer/lexer.go	95.09% <ø> (ø)
pkg/strings/strings.go	100.00% <ø> (ø)
pkg/token/token.go	100.00% <ø> (ø)
pkg/evaluator/builtins.go	87.83% <0.00%> (-5.02%)	⬇️
pkg/evaluator/quote_unqote.go	78.94% <78.94%> (ø)
pkg/parser/parser.go	79.13% <60.00%> (-0.79%)	⬇️
pkg/repl/repl.go	0.00% <0.00%> (ø)
pkg/object/environment.go	0.00% <0.00%> (ø)
pkg/ast/modify.go	86.95% <86.95%> (ø)
... and 3 more