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bind expression (:=) instead of let
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This commit is contained in:
Chuck Smith
2024-03-21 17:43:03 -04:00
parent 66d5453ecc
commit 6282075e66
36 changed files with 425 additions and 583 deletions
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29
evaluator/evaluator.go
View File

@@ -45,6 +45,23 @@ func Eval(node ast.Node, env *object.Environment) object.Object {
}
return &object.ReturnValue{Value: val}
case *ast.BindExpression:
value := Eval(node.Value, env)
if isError(value) {
return value
}
if ident, ok := node.Left.(*ast.Identifier); ok {
if immutable, ok := value.(object.Immutable); ok {
env.Set(ident.Value, immutable.Clone())
} else {
env.Set(ident.Value, value)
}
return NULL
}
return newError("expected identifier on left got=%T", node.Left)
case *ast.AssignmentExpression:
left := Eval(node.Left, env)
if isError(left) {
@@ -94,18 +111,6 @@ func Eval(node ast.Node, env *object.Environment) object.Object {
return NULL
case *ast.LetStatement:
val := Eval(node.Value, env)
if isError(val) {
return val
}
if immutable, ok := val.(object.Immutable); ok {
env.Set(node.Name.Value, immutable.Clone())
} else {
env.Set(node.Name.Value, val)
}
case *ast.Identifier:
return evalIdentifier(node, env)

84
evaluator/evaluator_test.go
View File

@@ -147,7 +147,7 @@ func TestReturnStatements(t *testing.T) {
},
{
`
let f = fn(x) {
f := fn(x) {
return x;
x + 10;
};
@@ -156,8 +156,8 @@ func TestReturnStatements(t *testing.T) {
},
{
`
let f = fn(x) {
let result = x + 10;
f := fn(x) {
result := x + 10;
return result;
return 10;
};
@@ -249,7 +249,7 @@ func TestIndexAssignmentStatements(t *testing.T) {
input string
expected int64
}{
{"let xs = [1, 2, 3]; xs[1] = 4; xs[1];", 4},
{"xs := [1, 2, 3]; xs[1] = 4; xs[1];", 4},
}
for _, tt := range tests {
@@ -263,16 +263,16 @@ func TestAssignmentStatements(t *testing.T) {
input string
expected interface{}
}{
{"let a = 0; a = 5;", nil},
{"let a = 0; a = 5; a;", 5},
{"let a = 0; a = 5 * 5;", nil},
{"let a = 0; a = 5 * 5; a;", 25},
{"let a = 0; a = 5; let b = 0; b = a;", nil},
{"let a = 0; a = 5; let b = 0; b = a; b;", 5},
{"let a = 0; a = 5; let b = 0; b = a; let c = 0; c = a + b + 5;", nil},
{"let a = 0; a = 5; let b = 0; b = a; let c = 0; c = a + b + 5; c;", 15},
{"let a = 5; let b = a; a = 0;", nil},
{"let a = 5; let b = a; a = 0; b;", 5},
{"a := 0; a = 5;", nil},
{"a := 0; a = 5; a;", 5},
{"a := 0; a = 5 * 5;", nil},
{"a := 0; a = 5 * 5; a;", 25},
{"a := 0; a = 5; b := 0; b = a;", nil},
{"a := 0; a = 5; b := 0; b = a; b;", 5},
{"a := 0; a = 5; b := 0; b = a; c := 0; c = a + b + 5;", nil},
{"a := 0; a = 5; b := 0; b = a; c := 0; c = a + b + 5; c;", 15},
{"a := 5; b := a; a = 0;", nil},
{"a := 5; b := a; a = 0; b;", 5},
}
for _, tt := range tests {
@@ -286,15 +286,15 @@ func TestAssignmentStatements(t *testing.T) {
}
}
func TestLetStatements(t *testing.T) {
func TestBindExpressions(t *testing.T) {
tests := []struct {
input string
expected int64
}{
{"let a = 5; a;", 5},
{"let a = 5 * 5; a;", 25},
{"let a = 5; let b = a; b;", 5},
{"let a = 5; let b = a; let c = a + b + 5; c;", 15},
{"a := 5; a;", 5},
{"a := 5 * 5; a;", 25},
{"a := 5; b := a; b;", 5},
{"a := 5; b := a; c := a + b + 5; c;", 15},
}
for _, tt := range tests {
@@ -331,11 +331,11 @@ func TestFunctionApplication(t *testing.T) {
input string
expected int64
}{
{"let identity = fn(x) { x; }; identity(5);", 5},
{"let identity = fn(x) { return x; }; identity(5);", 5},
{"let double = fn(x) { x * 2; }; double(5);", 10},
{"let add = fn(x, y) { x + y; }; add(5, 5);", 10},
{"let add = fn(x, y) { x + y; }; add(5 + 5, add(5, 5));", 20},
{"identity := fn(x) { x; }; identity(5);", 5},
{"identity := fn(x) { return x; }; identity(5);", 5},
{"double := fn(x) { x * 2; }; double(5);", 10},
{"add := fn(x, y) { x + y; }; add(5, 5);", 10},
{"add := fn(x, y) { x + y; }; add(5 + 5, add(5, 5));", 20},
{"fn(x) { x; }(5)", 5},
}
@@ -346,11 +346,11 @@ func TestFunctionApplication(t *testing.T) {
func TestClosures(t *testing.T) {
input := `
let newAdder = fn(x) {
newAdder := fn(x) {
fn(y) { x + y };
};
let addTwo = newAdder(2);
addTwo := newAdder(2);
addTwo(2);`
testIntegerObject(t, testEval(input), 4)
@@ -496,7 +496,7 @@ func TestArrayIndexExpressions(t *testing.T) {
3,
},
{
"let i = 0; [1][i];",
"i := 0; [1][i];",
1,
},
{
@@ -504,15 +504,15 @@ func TestArrayIndexExpressions(t *testing.T) {
3,
},
{
"let myArray = [1, 2, 3]; myArray[2];",
"myArray := [1, 2, 3]; myArray[2];",
3,
},
{
"let myArray = [1, 2, 3]; myArray[0] + myArray[1] + myArray[2];",
"myArray := [1, 2, 3]; myArray[0] + myArray[1] + myArray[2];",
6,
},
{
"let myArray = [1, 2, 3]; let i = myArray[0]; myArray[i]",
"myArray := [1, 2, 3]; i := myArray[0]; myArray[i]",
2,
},
{
@@ -538,7 +538,7 @@ func TestArrayIndexExpressions(t *testing.T) {
}
func TestHashLiterals(t *testing.T) {
input := `let two = "two";
input := `two := "two";
{
"one": 10 - 9,
two: 1 + 1,
@@ -621,7 +621,7 @@ func TestHashIndexExpressions(t *testing.T) {
nil,
},
{
`let key = "foo"; {"foo": 5}[key]`,
`key := "foo"; {"foo": 5}[key]`,
5,
},
{
@@ -660,14 +660,14 @@ func TestWhileExpressions(t *testing.T) {
expected interface{}
}{
{"while (false) { }", nil},
{"let n = 0; while (n < 10) { let n = n + 1 }; n", 10},
{"let n = 10; while (n > 0) { let n = n - 1 }; n", 0},
{"let n = 0; while (n < 10) { let n = n + 1 }", nil},
{"let n = 10; while (n > 0) { let n = n - 1 }", nil},
{"let n = 0; while (n < 10) { n = n + 1 }; n", 10},
{"let n = 10; while (n > 0) { n = n - 1 }; n", 0},
{"let n = 0; while (n < 10) { n = n + 1 }", nil},
{"let n = 10; while (n > 0) { n = n - 1 }", nil},
{"n := 0; while (n < 10) { n := n + 1 }; n", 10},
{"n := 10; while (n > 0) { n := n - 1 }; n", 0},
{"n := 0; while (n < 10) { n := n + 1 }", nil},
{"n := 10; while (n > 0) { n := n - 1 }", nil},
{"n := 0; while (n < 10) { n = n + 1 }; n", 10},
{"n := 10; while (n > 0) { n = n - 1 }; n", 0},
{"n := 0; while (n < 10) { n = n + 1 }", nil},
{"n := 10; while (n > 0) { n = n - 1 }", nil},
}
for _, tt := range tests {
@@ -778,7 +778,7 @@ func TestStringIndexExpressions(t *testing.T) {
"c",
},
{
`let i = 0; "abc"[i];`,
`i := 0; "abc"[i];`,
"a",
},
{
@@ -786,7 +786,7 @@ func TestStringIndexExpressions(t *testing.T) {
"c",
},
{
`let myString = "abc"; myString[0] + myString[1] + myString[2];`,
`myString := "abc"; myString[0] + myString[1] + myString[2];`,
"abc",
},
{