Expression Types Continued
•
Elimination rule (destructor)
D
;
G
|- M : A
D
,u::A ;
G
|- N : C
D
;
G
|- (let box u = M in N) : C
•
Operational semantics captures staging
M
Þ
box E
[E/u] N
Þ
V
box E
Þ
box E
let box u = M in N
Þ
V