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Merged
mathieu-lemay merged 2 commits into from
Aug 31, 2026
Merged

feat: Option and Result should not be used as pointers #9

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1ee9e61
[skip ci] WIP: 04-no-ptrs
mathieu-lemay Aug 29, 2026
7f74f49
Option and Result should not be used as pointers
mathieu-lemay Aug 29, 2026
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58 changes: 28 additions & 30 deletions safetypes/option.go
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Original file line number Diff line number Diff line change
Expand Up @@ -7,25 +7,25 @@ import (
)

// None creates a None variant of Option.
func None[T any]() *Option[T] {
func None[T any]() Option[T] {
var v T

return &Option[T]{
return Option[T]{
ok: false,
val: v,
}
}

// Some creates a Some variant of Option from the value.
func Some[T any](val T) *Option[T] {
return &Option[T]{
func Some[T any](val T) Option[T] {
return Option[T]{
ok: true,
val: val,
}
}

// OptionOf creates an Option from the given value.
func OptionOf[T any](val T) *Option[T] {
func OptionOf[T any](val T) Option[T] {
if reflect.ValueOf(&val).Elem().IsZero() {
return None[T]()
}
Expand All @@ -37,7 +37,7 @@ func OptionOf[T any](val T) *Option[T] {
// (if None).
//
// With Go 1.27+, use Option[T].Map().
func MapOption[T any, U any](opt *Option[T], f func(T) U) *Option[U] {
func MapOption[T any, U any](opt Option[T], f func(T) U) Option[U] {
if !opt.ok {
return None[U]()
}
Expand All @@ -48,7 +48,7 @@ func MapOption[T any, U any](opt *Option[T], f func(T) U) *Option[U] {
// MapOptionOr returns the provided default result (if None), or applies a function to the contained value (if Some).
//
// With Go 1.27+, use Option[T].MapOr().
func MapOptionOr[T any, U any](opt *Option[T], def U, f func(T) U) U {
func MapOptionOr[T any, U any](opt Option[T], def U, f func(T) U) U {
if !opt.ok {
return def
}
Expand All @@ -60,7 +60,7 @@ func MapOptionOr[T any, U any](opt *Option[T], def U, f func(T) U) U {
// (if Some).
//
// With Go 1.27+, use Option[T].MapOrElse().
func MapOptionOrElse[T any, U any](opt *Option[T], factory func() U, f func(T) U) U {
func MapOptionOrElse[T any, U any](opt Option[T], factory func() U, f func(T) U) U {
if !opt.ok {
return factory()
}
Expand All @@ -71,7 +71,7 @@ func MapOptionOrElse[T any, U any](opt *Option[T], factory func() U, f func(T) U
// And returns None if the Option is None, otherwise returns `optb`.
//
// With Go 1.27+, use Option[T].And().
func And[T any, U any](opt *Option[T], other *Option[U]) *Option[U] {
func And[T any, U any](opt Option[T], other Option[U]) Option[U] {
if !opt.ok {
return None[U]()
}
Expand All @@ -82,7 +82,7 @@ func And[T any, U any](opt *Option[T], other *Option[U]) *Option[U] {
// AndThen returns None if the Option is None, otherwise calls `f` with the wrapped value and returns the result.
//
// With Go 1.27+, use Option[T].AndThen().
func AndThen[T any, U any](opt *Option[T], f func(T) *Option[U]) *Option[U] {
func AndThen[T any, U any](opt Option[T], f func(T) Option[U]) Option[U] {
if !opt.ok {
return None[U]()
}
Expand Down Expand Up @@ -172,7 +172,7 @@ func (o *Option[T]) UnwrapOrDefault() T {
}

// AsOkOr converts an Option to an Ok when opt is Some or Err when opt is None.
func (o *Option[T]) AsOkOr(err error) *Result[T] {
func (o *Option[T]) AsOkOr(err error) Result[T] {
if o.ok {
return Ok[T](o.val)
}
Expand All @@ -181,7 +181,7 @@ func (o *Option[T]) AsOkOr(err error) *Result[T] {
}

// AsOkOrElse converts an Option to an Ok when opt is Some or Err when opt is None.
func (o *Option[T]) AsOkOrElse(f func() error) *Result[T] {
func (o *Option[T]) AsOkOrElse(f func() error) Result[T] {
if o.ok {
return Ok[T](o.val)
}
Expand All @@ -190,51 +190,51 @@ func (o *Option[T]) AsOkOrElse(f func() error) *Result[T] {
}

// Inspect calls a function with a reference to the contained value if Some. Returns the original Option.
func (o *Option[T]) Inspect(f func(T)) *Option[T] {
func (o *Option[T]) Inspect(f func(T)) Option[T] {
if o.ok {
f(o.val)
}

return o
return *o
}

// Filter returns None if the Option is None, otherwise calls predicate with the wrapped value and returns:
// - Some(t) if the predicate returns true (where t is the wrapped value), and
// - None if the predicate returns false.
func (o *Option[T]) Filter(f func(T) bool) *Option[T] {
func (o *Option[T]) Filter(f func(T) bool) Option[T] {
if o.ok && f(o.val) {
return o
return *o
}

return None[T]()
}

// Or returns the Option if it contains a value, otherwise returns optb.
func (o *Option[T]) Or(other *Option[T]) *Option[T] {
func (o *Option[T]) Or(other Option[T]) Option[T] {
if o.ok {
return o
return *o
}

return other
}

// OrElse returns the option if it contains a value, otherwise calls f and returns the result.
func (o *Option[T]) OrElse(f func() *Option[T]) *Option[T] {
func (o *Option[T]) OrElse(f func() Option[T]) Option[T] {
if o.ok {
return o
return *o
}

return f()
}

// Xor returns Some if exactly one of self, optb is Some, otherwise returns None.
func (o *Option[T]) Xor(other *Option[T]) *Option[T] {
func (o *Option[T]) Xor(other Option[T]) Option[T] {
if o.ok == other.ok {
return None[T]()
}

if o.ok {
return o
return *o
}

return other
Expand Down Expand Up @@ -295,30 +295,28 @@ func (o *Option[T]) GetOrInsertWith(f func() T) *T {
}

// Take takes the value out of the Option, leaving a None in its place.
func (o *Option[T]) Take() *Option[T] {
if o.ok {
res := *o
func (o *Option[T]) Take() Option[T] {
res := *o

if o.ok {
o.ok = false

return &res
}

return o
return res
}

// TakeIf takes the value out of the Option, but only if the predicate evaluates to true on a mutable reference to
// the value.
//
// In other words, replaces self with None if the predicate returns true. This method operates similar to take but
// conditional.
func (o *Option[T]) TakeIf(f func(T) bool) *Option[T] {
func (o *Option[T]) TakeIf(f func(T) bool) Option[T] {
if o.ok && f(o.val) {
res := *o

o.ok = false

return &res
return res
}

return None[T]()
Expand Down
8 changes: 4 additions & 4 deletions safetypes/option1.27.go
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Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,7 @@ package st

// Map maps an Option<T> to Option<U> by applying a function to a contained value (if Some) or returns None
// (if None).
func (o *Option[T]) Map[U any](f func(T) U) *Option[U] {
func (o *Option[T]) Map[U any](f func(T) U) Option[U] {
if !o.ok {
return None[U]()
}
Expand Down Expand Up @@ -32,16 +32,16 @@ func (o *Option[T]) MapOrElse[U any](factory func() U, f func(T) U) U {
}

// And returns None if the option is None, otherwise returns `optb`.
func (o *Option[T]) And[U any](other *Option[U]) *Option[U] {
func (o *Option[T]) And[U any](other Option[U]) Option[U] {
if !o.ok {
return None[U]()
}

return other
}

// AndThen returns None if the option is None, otherwise calls `f` with the wrapped value and returns the result.
func (o *Option[T]) AndThen[U any](f func(T) *Option[U]) *Option[U] {
// AndThen returns None if the option is None, otherwise calls `f` with the wrapped value, and returns the result.
func (o *Option[T]) AndThen[U any](f func(T) Option[U]) Option[U] {
if !o.ok {
return None[U]()
}
Expand Down
4 changes: 2 additions & 2 deletions safetypes/option1.27_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -121,15 +121,15 @@ func TestOption_AndThen(t *testing.T) {
value := fake.RandomStringWithLength(8)
other := Some(value)

res := o.AndThen(func(int) *Option[string] { return other })
res := o.AndThen(func(int) Option[string] { return other })

assert.Equal(t, other, res)
})

t.Run("none", func(t *testing.T) {
o := None[int]()

f := func(int) *Option[string] {
f := func(int) Option[string] {
assert.Fail(t, "mapper should not have been called")

return Some("")
Expand Down
4 changes: 2 additions & 2 deletions safetypes/option_marshal.go
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Original file line number Diff line number Diff line change
Expand Up @@ -3,8 +3,8 @@ package st
import "encoding/json"

// MarshalJSON implements json.Marshaler.
func (o *Option[T]) MarshalJSON() ([]byte, error) {
if o == nil || !o.ok {
func (o Option[T]) MarshalJSON() ([]byte, error) {
if !o.ok {
return []byte("null"), nil
}

Expand Down
8 changes: 4 additions & 4 deletions safetypes/option_marshal_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -47,15 +47,15 @@ func TestMarshalJSON(t *testing.T) {
struct {
Name string
Job *Option[string]
}{"Poor Schmuck", None[string]()},
}{"Poor Schmuck", ptr(None[string]())},
`{"Name": "Poor Schmuck", "Job": null}`,
},
{
"some inside a struct",
struct {
Name string
Job *Option[string]
}{"Mega Chad", Some("Big Boss")},
}{"Mega Chad", ptr(Some("Big Boss"))},
`{"Name": "Mega Chad", "Job": "Big Boss"}`,
},
}
Expand Down Expand Up @@ -125,7 +125,7 @@ func TestUnmarshalText(t *testing.T) {
err := json.Unmarshal([]byte(`{"Name": "Poor Schmuck", "Job": null}`), &o)
require.NoError(t, err)

expected := Option[S]{ok: true, val: S{"Poor Schmuck", *None[string]()}}
expected := Option[S]{ok: true, val: S{"Poor Schmuck", None[string]()}}
assert.Equal(t, expected, o)
})

Expand All @@ -139,7 +139,7 @@ func TestUnmarshalText(t *testing.T) {
err := json.Unmarshal([]byte(`{"Name": "Mega Chad", "Job": "Big Boss"}`), &o)
require.NoError(t, err)

expected := Option[S]{ok: true, val: S{"Mega Chad", *Some("Big Boss")}}
expected := Option[S]{ok: true, val: S{"Mega Chad", Some("Big Boss")}}
assert.Equal(t, expected, o)
})

Expand Down
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