Primitive operations 1
let plus (x,y) = match (x,y) with
|(Int nx, Int ny) -> Int (nx + ny)
let diff (x,y) = match (x,y) with
|(Int nx, Int ny) -> Int (nx - ny)
let valid x = match x with
let unsatisfiable x = match x with
|Int n -> if n=0 then false else true
let merge (a,b,c) = match a with
|Int n -> if b=c then b else Wrong
let applyfun ((x:eval),(y:eval)) = match x with
let rec makefun(ii,aa,r) = Funval(function d ->
else sem aa (bind(r,ii,d)))