Tipi e pattern matching

type expr =

| Den of ide

| Fun of ide * expr

| Plus of expr * expr

| Apply of expr * expr

type eval = | Int of int | Bool of bool | Efun of myfun | Unbound

type myfun = eval -> eval

type env = ide -> eval

E(I) = ______(I)

E(plus(E1, E2))= _____ (E(E1) __) + (E(E2) __)

E(lambda(I, E1))= __________ E(E1) [r / I _ d ]

E(apply(E1, E2)) = _____ (E(E1) ____E(E2) _)

# let rec sem e rho = match e with

| Den i -> rho i

| Plus(e1, e2) -> plus(sem e1 rho, sem e2 rho)

| Fun(i, e) -> Efun(function d -> sem e (bind(rho, i, d)))

| Apply(e1, e2) -> match sem e1 rho with

| Efun f -> f (sem e2 rho)

| _ -> failwith("wrong application");;

val sem : expr -> env -> eval =

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