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chengluyuchengluyu
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Add some examples of unhygienic let bindings
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‎shared/src/test/diff/ucs/HygienicBindings.mls

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:NewDefs
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type Option[out T] = None | Some[T]
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module None
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class Some[out T](value: T)
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//│ type Option[T] = Some[T] | None
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//│ module None()
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//│ class Some[T](value: T)
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type Either[A, B] = Left[A] | Right[B]
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class Left[A](leftValue: A)
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class Right[B](rightValue: B)
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//│ type Either[A, B] = Left[A] | Right[B]
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//│ class Left[A](leftValue: A)
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//│ class Right[B](rightValue: B)
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type List[out A] = Nil | Cons[A]
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module Nil
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class Cons[out A](head: A, tail: List[A])
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//│ type List[A] = Cons[A] | Nil
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//│ module Nil()
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//│ class Cons[A](head: A, tail: List[A])
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fun h0(a) =
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if
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a is Some(Left(y)) then y
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a is Some(Right(z)) then z
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a is None then 0
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//│ fun h0: forall 'leftValue. (None | Some[Left['leftValue] | Right['leftValue]]) -> (0 | 'leftValue)
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// FIXME: Precise scrutinee identification (easy)
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// This seems fine. But the subtrees are not merged.
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fun h1(a) =
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if
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a is Some(x) and x is Left(y) then y
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a is Some(y) and y is Right(z) then z
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a is None then 0
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//│ fun h1: forall 'leftValue. (None | Some[Right['leftValue]]) -> (0 | 'leftValue)
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// FIXME: This is the desugared version of the test case above.
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fun h1'(a) =
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if a is
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Some then
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let x = a.value
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let y = a.value
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if x is
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Left then
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let y = x.leftValue
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y
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_ then
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if y is
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Right then
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let z = y.rightValue
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z
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None then 0
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//│ fun h1': forall 'leftValue. (None | Some[Right['leftValue]]) -> (0 | 'leftValue)
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// FIXME This seems fine but the desugared term does not merge the cases.
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// See the example below.
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fun h1''(a) =
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if
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a is Some(x) and x is Left(y) then y
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a is Some(x) and x is Right(z) then z
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a is None then 0
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//│ fun h1'': forall 'leftValue. (None | Some[Left['leftValue] | Right['leftValue]]) -> (0 | 'leftValue)
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// FIXME
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h1(Some(Left(0)))
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h1'(Some(Left(0)))
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h1''(Some(Left(0)))
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//│ ╔══[ERROR] Type mismatch in application:
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//│ ║ l.68: h1(Some(Left(0)))
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//│ ║ ^^^^^^^^^^^^^^^^^
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//│ ╟── application of type `Left[?A]` is not an instance of type `Right`
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//│ ║ l.68: h1(Some(Left(0)))
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//│ ║ ^^^^^^^
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//│ ╟── Note: constraint arises from class pattern:
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//│ ║ l.36: a is Some(y) and y is Right(z) then z
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//│ ║ ^^^^^
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//│ ╟── from reference:
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//│ ║ l.35: a is Some(x) and x is Left(y) then y
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//│ ║ ^
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//│ ╟── Note: type parameter T is defined at:
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//│ ║ l.5: class Some[out T](value: T)
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//│ ╙── ^
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//│ ╔══[ERROR] Type mismatch in application:
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//│ ║ l.69: h1'(Some(Left(0)))
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//│ ║ ^^^^^^^^^^^^^^^^^^
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//│ ╟── application of type `Left[?A]` is not an instance of type `Right`
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//│ ║ l.69: h1'(Some(Left(0)))
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//│ ║ ^^^^^^^
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//│ ╟── Note: constraint arises from class pattern:
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//│ ║ l.52: Right then
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//│ ║ ^^^^^
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//│ ╟── from field selection:
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//│ ║ l.45: let y = a.value
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//│ ║ ^^^^^^^
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//│ ╟── Note: type parameter T is defined at:
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//│ ║ l.5: class Some[out T](value: T)
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//│ ╙── ^
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//│ 0
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//│ res
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//│ = 0
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//│ res
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//│ = 0
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//│ res
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//│ = 0
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// FIXME: Precise scrutinee identification (hard)
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fun h2(a) =
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if
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a is Some(x) and x is x' and x' is Left(y) then y
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a is Some(y) and
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let y' = y
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y' is Right(z) then z
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a is None then 0
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//│ ╔══[ERROR] identifier not found: y
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//│ ║ l.114: let y' = y
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//│ ╙── ^
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//│ ╔══[ERROR] identifier not found: y
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//│ ║ l.114: let y' = y
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//│ ╙── ^
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//│ fun h2: forall 'leftValue. (None | Some[Left['leftValue] | ~Left[anything]]) -> (0 | error | 'leftValue)
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//│ Code generation encountered an error:
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//│ unresolved symbol y
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// FIXME
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fun h3(x, y, f, p) =
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if x is
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_ and f(x) is y and p(x) then y
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None then y
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_ then "anyway"
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h3("anything", "not me", _ => "should be me", _ => true)
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h3(None, "should be me", _ => "not me", _ => false)
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h3("anything", "anything", _ => "not me", _ => false)
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//│ fun h3: forall 'a 'b. (None | 'a & ~#None, 'b, (None | 'a) -> anything, (None | 'a) -> anything,) -> ("anyway" | 'b)
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//│ "anything" | "anyway"
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//│ res
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//│ = [Function: h3]
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//│ res
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//│ = 'not me'
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//│ res
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//│ = 'should be me'
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// FIXME
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fun h4(x, y, p) =
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if x is
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y and p(x) then y
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None then y
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_ then "default"
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h4("should be me", "not me", _ => true) // WRONG!
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h4(None, "not me", _ => true) // WRONG!
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h4(None, "should be me", _ => false)
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h4("anything", "not me", _ => false)
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//│ fun h4: forall 'a 'b. (None | 'a & ~#None, 'b, (None | 'a) -> anything,) -> ("default" | 'b)
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//│ "default" | "not me"
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//│ res
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//│ = [Function: h4]
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//│ res
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//│ = 'not me'
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//│ res
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//│ = 'not me'
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//│ res
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//│ = 'should be me'

‎shared/src/test/diff/ucs/Wildcard.mls

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Original file line numberDiff line numberDiff line change
@@ -235,3 +235,29 @@ w6("42", "42")
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//│ = 0
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//│ res
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//│ = '42'
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// FIXME
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// Should report warnings.
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fun w7(x, f) =
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if x is
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_ and f(x) is
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Some(v) then v
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None then x
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Left(x) then x + 1
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Right(x) then x + 2
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//│ fun w7: forall 'a 'value. (Left[int] | Right[int] | 'a & ~#Left & ~#Right, 'a -> (None | Some['value]),) -> (int | 'value | 'a)
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// The results are wrong:
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w7(Left(99), _ => Some(0)) // => 0
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w7(Left(99), _ => None) // => Left(99)
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w7(Right(99), _ => Some(0)) // => 0
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w7(Right(99), _ => None) // => Right(99)
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//│ int
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//│ res
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//│ = 100
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//│ res
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//│ = 100
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//│ res
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//│ = 101
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//│ res
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//│ = 101

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