我有以下定义类型,并尝试评估该函数作为示例:
let evn =[("z1",Int 0);("x",Int 1);("y",Int 2);("z",Int 3);("z1",Int 4)];;
val evn : (string * Nano.value) list = [("z1", Int 0); ("x", Int 1); ("y", Int 2); ("z", Int 3); ("z1", Int 4)]
# let e1 =Bin(Bin(Var "x",Plus,Var "y"), Minus, Bin(Var "z",Plus,Var "z1"));;
val e1 : Nano.expr = Bin (Bin (Var "x", Plus, Var "y"), Minus, Bin (Var "z", Plus, Var "z1"))
# eval (evn,e1);;
- : Nano.value = Int 0
# eval (evn,Var "p");;
Exception: Nano.MLFailure "Variable not bound: p". …