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47 lines
960 B
Go
47 lines
960 B
Go
3 years ago
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package opt
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// Val is an optional value
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type Val[T any] struct {
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val T
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ok bool
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}
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// New creates an optional value
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func New[T any](v T, ok bool) Val[T] {
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if ok {
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return Some(v)
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}
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return None[T]()
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}
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// None creates an empty optional value
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func None[T any]() Val[T] { return Val[T]{} }
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// NoneOf is the same as none, but it takes a parameter that it throws away.
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// This allows the type T to be inferred.
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func NoneOf[T any](v T) Val[T] { return Val[T]{} }
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// Some creates a filled optional value
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func Some[T any](v T) Val[T] {
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return Val[T]{
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val: v,
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ok: true,
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}
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}
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// Open retrives the contents of our optional value
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func (v Val[T]) Open() (T, bool) {
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return v.val, v.ok
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}
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// Bind takes a function that doesn't understand optionals and gives you
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// another function that does
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func Bind[X, Y any](f func(X) Y) func(Val[X]) Val[Y] {
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return func(mx Val[X]) Val[Y] {
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if x, ok := mx.Open(); ok {
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return Some(f(x))
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}
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return None[Y]()
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}
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}
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