X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=blobdiff_plain;f=code%2Fcalculator%2Fcalc2.ml;fp=code%2Fcalculator%2Fcalc2.ml;h=0000000000000000000000000000000000000000;hp=521b81ddcfb2eb757af61febbc30dee549091604;hb=fd698b815e417dec463cb0f0e9ed056ab83daed6;hpb=573a8b36ce653c84c2aecb2b81ef99128cb41d13 diff --git a/code/calculator/calc2.ml b/code/calculator/calc2.ml deleted file mode 100644 index 521b81dd..00000000 --- a/code/calculator/calc2.ml +++ /dev/null @@ -1,68 +0,0 @@ -(* calc2.ml: calc1.ml enhanced with Function Values *) - - type term = - Intconstant of int - | Multiplication of (term * term) - | Addition of (term * term) - | Variable of char - | Let of (char * term * term) - | Iszero of term - | If of (term * term * term) - | Makepair of (term * term) - | First of term - | Lambda of (char * term) - | Apply of (term * term) - ;; - - type bound_value = expressed_value - and assignment = (char * bound_value) list - and expressed_value = Int of int | Bool of bool | Pair of expressed_value * expressed_value | Closure of char * term * assignment;; - - let rec eval (t : term) (g : assignment) = match t with - Intconstant x -> Int x - | Multiplication (t1, t2) -> - (* we don't handle cases where the subterms don't evaluate to Ints *) - let Int i1 = eval t1 g - in let Int i2 = eval t2 g - (* Multiplication (t1, t2) should evaluate to an Int *) - in Int (i1 * i2) - | Addition (t1, t2) -> - let Int i1 = eval t1 g - in let Int i2 = eval t2 g - in Int (i1 + i2) - | Variable (var) -> - (* we don't handle cases where g doesn't bind var to any value *) - List.assoc var g - | Let (var_to_bind, t2, t3) -> - (* evaluate t3 under a new assignment where var_to_bind has been bound to - the result of evaluating t1 under the current assignment *) - let value2 = eval t2 g - in let g' = (var_to_bind, value2) :: g - in eval t3 g' - | Iszero (t1) -> - (* we don't handle cases where t1 doesn't evaluate to an Int *) - let Int i1 = eval t1 g - (* Iszero t1 should evaluate to a Bool *) - in Bool (i1 = 0) - | If (t1, t2, t3) -> - (* we don't handle cases where t1 doesn't evaluate to a boolean *) - let Bool b1 = eval t1 g - in if b1 then eval t2 g - else eval t3 g - | Makepair (t1, t2) -> - let value1 = eval t1 g - in let value2 = eval t2 g - in Pair (value1, value2) - | First (t1) -> - (* we don't handle cases where t1 doesn't evaluate to a Pair *) - let Pair (value1, value2) = eval t1 g - in value1 - | Lambda (arg_var, t2) -> Closure (arg_var, t2, g) - | Apply (t1, t2) -> - (* we don't handle cases where t1 doesn't evaluate to a function value *) - let Closure (arg_var, body, savedg) = eval t1 g - in let value2 = eval t2 g - (* evaluate body under savedg, except with arg_var bound to value2 *) - in let savedg' = (arg_var, value2) :: savedg - in eval body savedg' - ;;