Added more tests

src/core/CompileAssignArray.go

@@ -7,7 +7,7 @@ import (
 	"git.akyoto.dev/cli/q/src/ast"
 	"git.akyoto.dev/cli/q/src/cpu"
 	"git.akyoto.dev/cli/q/src/errors"
-	"git.akyoto.dev/cli/q/src/token"
+	"git.akyoto.dev/cli/q/src/types"
 )
 
 // CompileAssignArray compiles an assign statement for array elements.
@@ -33,7 +33,7 @@ func (f *Function) CompileAssignArray(node *ast.Assign) error {
 
 	index := left.Children[1]
 
-	if index.Token.Kind == token.Number {
+	if index.Token.IsNumeric() {
 		offset, err := f.Number(index.Token)
 
 		if err != nil {
@@ -42,12 +42,16 @@ func (f *Function) CompileAssignArray(node *ast.Assign) error {
 
 		memory.Offset = int8(offset)
 	} else {
-		_, indexRegister, isTemporary, err := f.Evaluate(index)
+		typ, indexRegister, isTemporary, err := f.Evaluate(index)
 
 		if err != nil {
 			return err
 		}
 
+		if !types.Is(typ, types.Int) {
+			return errors.New(&errors.TypeMismatch{Encountered: typ.Name(), Expected: types.Int.Name()}, f.File, index.Token.Position)
+		}
+
 		memory.OffsetRegister = indexRegister
 
 		if isTemporary {

src/core/CompileDefinition.go

@@ -25,12 +25,11 @@ func (f *Function) CompileDefinition(node *ast.Define) error {
 			return err
 		}
 
-		variable.Type = typ
-
-		if variable.Type == nil {
-			return errors.New(errors.CouldNotInferType, f.File, node.Expression.Token.End())
+		if typ == nil {
+			return errors.New(errors.UntypedExpression, f.File, node.Expression.Token.End())
 		}
 
+		variable.Type = typ
 		f.AddVariable(variable)
 		return nil
 	}

src/core/ExpressionToRegister.go

@@ -1,6 +1,8 @@
 package core
 
 import (
+	"math"
+
 	"git.akyoto.dev/cli/q/src/asm"
 	"git.akyoto.dev/cli/q/src/ast"
 	"git.akyoto.dev/cli/q/src/cpu"
@@ -40,10 +42,46 @@ func (f *Function) ExpressionToRegister(node *expression.Expression, register cp
 	}
 
 	if node.Token.Kind == token.Array {
-		array := f.VariableByName(node.Children[0].Token.Text(f.File.Bytes))
-		offset, err := f.Number(node.Children[1].Token)
-		f.MemoryRegister(asm.LOAD, asm.Memory{Base: array.Register, Offset: int8(offset), Length: 1}, register)
-		return types.Int, err
+		name := node.Children[0].Token.Text(f.File.Bytes)
+		array := f.VariableByName(name)
+
+		if array == nil {
+			return nil, errors.New(&errors.UnknownIdentifier{Name: name}, f.File, node.Children[0].Token.Position)
+		}
+
+		index := node.Children[1]
+
+		memory := asm.Memory{
+			Base:           array.Register,
+			Offset:         0,
+			OffsetRegister: cpu.Register(math.MaxUint8),
+			Length:         byte(1),
+		}
+
+		if index.Token.IsNumeric() {
+			offset, err := f.Number(index.Token)
+
+			if err != nil {
+				return nil, err
+			}
+
+			memory.Offset = int8(offset)
+		} else {
+			typ, err := f.ExpressionToRegister(index, register)
+
+			if err != nil {
+				return nil, err
+			}
+
+			if !types.Is(typ, types.Int) {
+				return nil, errors.New(&errors.TypeMismatch{Encountered: typ.Name(), Expected: types.Int.Name()}, f.File, index.Token.Position)
+			}
+
+			memory.OffsetRegister = register
+		}
+
+		f.MemoryRegister(asm.LOAD, memory, register)
+		return types.Int, nil
 	}
 
 	if node.Token.Kind == token.Period {