The Fortress Language Specification - CiteSeerX

Function/method name lookup: Fname(fd) = f
−−−−−−−−−−−→
Fname(fαextends { −→ K}( −→ x:τ):τ = e) = f
Types of values: type(v) = τ
type(O −→ τ ( −→ v )) = O −→ τ
Finding witnesses from the static type of the receiver: witness p (τ, τ) = S
witness p (τ, τ ′ ) =
⎧
⎪⎨
⎪⎩
[ ] if τ ′ = Object
match(C −→ τ , C −→ τ ′ ) if τ = C −→ τ and τ ′ = C −→ τ ′
S n · · · S 1 if τ = C −→ τ , τ ′ = C ′ −→ τ ′ , C ≠ C ′ ,
C −−−−−−−−−→ αextends extends { −→ N } ∈ p,
and witness p ([ −→ τ / −→ α ]N i , C ′ −→ τ ′ ) = S i for N i ∈ { −→ N }
[ ] otherwise
Match two types to get substitutions: match(τ, τ) = S
match(τ, τ ′ ) =
⎧
⎪⎨
⎪⎩
[ ] if τ = τ ′
[τ ′ /β] if τ = β
S n · · · S 1 if τ = C −→ τ , τ ′ = C −→ τ ′ , and match(S i−1 · · · S 1 τ i , τ ′ i ) = S i for 1 ≤ i ≤ n
[ ] otherwise
Figure A.8: Dynamic Semantics of Core Fortress with Where Clauses (II)
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