[interpreter,spec] Convert MTValue into an alias of native types an…

…d `MutableValue`s.

Instead of using wrapper classes for the primitive types of `TInteger`, `TFloat`, `TString`, and `TBoolean`, these values are now implemented directly as the underlying Crystal types: `Int64`, `Float64`, `String`, and `Bool` respectively. `TList` and `TMap` may also be converted over to use `Array` and `Hash` directly in the near future.

`TNil` and `TSymbol` will remain non-native types. `TNil` will remain because it would conflict in many cases with Crystal's standard library returning `nil` in many cases (this is already enough of an issue with `false`). `TSymbol` needs to remain to be able to retain the name of the Symbol at run time.

There are two main reasons for implementing this change:
- **Performance improvements.** While not overly substantial (~0.1% speed-wise in a super-quick test benchmark), the interpreter no longer needs to allocate a whole object on the heap to represent integers, floats, or booleans (strings will still be allocated on the heap). In the long run, this will help with both speed and memory.
- **Cleaner native library work.** Native library methods no longer need to wrap and unwrap values to work with them. Since these values are literally the Crystal objects themselves, they can be manipulated directly.

spec/interpreter/callstack_spec.cr

@@ -81,8 +81,7 @@ describe "Interpreter - Callstack" do
     it "removes the last entry from the callstack" do
       itr = Interpreter.new
       add_breakpoint(itr, "breakpoint") do
-        expected_stack_size = __args[0].as(TInteger).value
-        itr.callstack.size.should eq(expected_stack_size)
+        itr.callstack.size.should eq(__args[0])
       end
 
       parse_and_interpret! %q(
@@ -100,8 +99,7 @@ describe "Interpreter - Callstack" do
       it "removes the last entry from the callstack" do
         itr = Interpreter.new
         add_breakpoint(itr, "breakpoint") do
-          expected_stack_size = __args[0].as(TInteger).value
-          itr.callstack.size.should eq(expected_stack_size)
+          itr.callstack.size.should eq(__args[0])
         end
 
         parse_and_interpret! %q(
@@ -121,8 +119,7 @@ describe "Interpreter - Callstack" do
     it "removes the `block` from the callstack" do
       itr = Interpreter.new
       add_breakpoint(itr, "breakpoint") do
-        expected_stack_size = __args[0].as(TInteger).value
-        itr.callstack.size.should eq(expected_stack_size)
+        itr.callstack.size.should eq(__args[0])
       end
 
       parse_and_interpret! %q(
@@ -137,8 +134,7 @@ describe "Interpreter - Callstack" do
     it "removes the `next` from the callstack" do
       itr = Interpreter.new
       add_breakpoint(itr, "breakpoint") do
-        expected_stack_size = __args[0].as(TInteger).value
-        itr.callstack.size.should eq(expected_stack_size)
+        itr.callstack.size.should eq(__args[0])
       end
 
       parse_and_interpret! %q(

spec/interpreter/closure_scope_spec.cr

@@ -9,7 +9,7 @@ describe "Interpreter - ClosureScope" do
       scope["b"]
     end
 
-    scope["b"]?.should be(nil)
+    scope["b"]?.should eq(nil)
   end
 
   describe "#[]" do
@@ -97,7 +97,7 @@ describe "Interpreter - ClosureScope" do
       scope = ClosureScope.new(Scope.new)
       scope["a"] = TNil.new
       scope["Thing"] = TType.new("Thing")
-      scope["x"] = TInteger.new(100_i64)
+      scope["x"] = 100_i64
 
       scope.values.size.should eq(3)
 

spec/interpreter/invocation_spec.cr

@@ -82,13 +82,13 @@ TYPE_DEFS = %q(
 )
 
 
-private def it_invokes(prelude, call, expected)
+private def it_invokes(prelude, call, expected, file=__FILE__, line=__LINE__, end_line=__END_LINE__)
   itr = parse_and_interpret(prelude)
   # Running the prelude will leave the last definition on the stack. For
   # clarity in the tests, the stack is cleared of any existing values before
   # making any assertions.
   itr.stack.clear
-  it_interprets(call, [expected] of MTValue, itr)
+  it_interprets(call, [expected] of MTValue, itr, file: file, line: line, end_line: end_line)
 end
 
 describe "Interpreter - Invocation" do

spec/interpreter/nodes/call_spec.cr

@@ -95,7 +95,7 @@ describe "Interpreter - Call" do
     # Operators can also be defined statically to do some type algebra.
     it_interprets %Q(
       deftype Foo
-        defstatic #{op}(other : Foo)
+        defstatic #{op}(other)
           :called_op_on_type
         end
       end

spec/interpreter/nodes/match_assign_spec.cr

@@ -3,15 +3,15 @@ require "../../support/nodes.cr"
 require "../../support/interpret.cr"
 
 private def it_matches(match, file=__FILE__, line=__LINE__, end_line=__END_LINE__)
-  it %Q(matches `#{match}`) do
+  it %Q(matches `#{match}`), file, line, end_line do
     itr = Interpreter.new
     program = parse_program(match)
     result = itr.run(program)
   end
 end
 
 private def it_does_not_match(match, file=__FILE__, line=__LINE__, end_line=__END_LINE__)
-  it %Q(does not match `#{match}`) do
+  it %Q(does not match `#{match}`), file, line, end_line do
     itr = Interpreter.new(errput: IO::Memory.new)
     program = parse_program(match)
 
@@ -50,7 +50,7 @@ describe "Interpreter - MatchAssign" do
   distinct_types.each_with_index do |a, i|
     distinct_types.each_with_index do |b, j|
       next if i == j
-      it_does_not_match "#{a} =: #{b}", /match/
+      it_does_not_match "#{a} =: #{b}"
     end
   end
 
@@ -59,8 +59,8 @@ describe "Interpreter - MatchAssign" do
   it_interprets %q(1    =: 1.0)
   it_interprets %q(1.0  =: 1)
 
-  it_does_not_match %q(1    =: 1.1),  /match/
-  it_does_not_match %q(1.1  =: 1),    /match/
+  it_does_not_match %q(1    =: 1.1)
+  it_does_not_match %q(1.1  =: 1)
 
 
   # Assignments at any level should either create or re-assign the variable
@@ -122,7 +122,7 @@ describe "Interpreter - MatchAssign" do
   it_does_not_match %q(
     A = false
     A =: true
-  ), /match/
+  )
 
   # Both styles of matching with Consts works through interpolation.
   it_interprets %q(<String>   =: "hello")
@@ -140,5 +140,5 @@ describe "Interpreter - MatchAssign" do
   it_does_not_match %q(
     float_type = 1.5.type
     <float_type> =: 1
-  ),  /match/
+  )
 end

spec/interpreter/scope_spec.cr

@@ -9,7 +9,7 @@ describe "Interpreter - Scope" do
       scope["b"]
     end
 
-    scope["b"]?.should be(nil)
+    scope["b"]?.should eq(nil)
   end
 
   describe "#[]" do
@@ -71,7 +71,7 @@ describe "Interpreter - Scope" do
       scope = Scope.new
       scope["a"] = TNil.new
       scope["Thing"] = TType.new("Thing")
-      scope["x"] = TInteger.new(100_i64)
+      scope["x"] = 100_i64
 
       scope.values.size.should eq(3)