Parentheses

HaskCalc can parse expressions containing parentheses now.
README.md (RbScm)
README.md

~6.6
string

RbScm can parse strings.
[refactor] rewrite tests(in progress)

rewrite tests (using test_eval, assert_equal)
refactor] rewrite tests(in progress)

rewrite tests (using test_eval, assert_equal)
define make_int in main.rb
[refactor] rewrite tests(in progress)

rewrite tests (using test_eval, assert_equal)
add tests for named let
[refactor] rewrite tests(in progress)

rewrite tests (using test_eval, assert_equal)
add code that counts successes and failures
[refactor] rewrite tests(in progress)

rewrite tests (using test_eval, assert_equal)
add tests and readme for section 4.1

4.1 Primitive expression types
[fix] assertion error to stderr

output assertion error to stderr