X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=blobdiff_plain;f=code%2Fcalculator%2Fcalc5.ml;h=593f296beb805553ab85e636f43e4b99fec06544;hp=bfc91d9ff66bc7fb889d8cf00ba3847855d4c91f;hb=060198e29e2a13552ee64c1e489eea555c8b1cae;hpb=bd90f2eb8b87c2f44169fe209c5e35dd113c3d21

diff --git a/code/calculator/calc5.ml b/code/calculator/calc5.ml
index bfc91d9f..593f296b 100644
--- a/code/calculator/calc5.ml
+++ b/code/calculator/calc5.ml
@@ -1,6 +1,6 @@
 (* calc3,ml, enhanced with Mutable Pairs *)
 
-	type term =
+    type term =
       Intconstant of int
     | Multiplication of (term * term)
     | Addition of (term * term)
@@ -16,90 +16,90 @@
     | Setfirst of (term * term)
     ;;
 
-	type index = int;;
+    type index = int;;
 
     type bound_value = Nonrecursive of expressed_value | Recursive_Closure of char * char * term * assignment
-	and assignment = (char * bound_value) list
+    and assignment = (char * bound_value) list
     and expressed_value = Int of int | Bool of bool | Pair of index * index | Closure of char * term * assignment;;
 
-	type store = expressed_value list;;
+    type store = expressed_value list;;
 
-	let rec eval (t : term) (g : assignment) (s : store) = match t with
-	  Intconstant x -> (Int x, s)
-	| Multiplication (t1, t2) ->
-		(* we don't handle cases where the subterms don't evaluate to Ints *)
-		let (Int i1, s') = eval t1 g s
-		in let (Int i2, s'') = eval t2 g s'
-		(* Multiplication (t1, t2) should evaluate to an Int *)
-		in (Int (i1 * i2), s'')
-	| Addition (t1, t2) ->
-		let (Int i1, s') = eval t1 g s
-		in let (Int i2, s'') = eval t2 g s'
-		in (Int (i1 + i2), s'')
-	| Variable (var) -> (
-		(* we don't handle cases where g doesn't bind var to any value *)
-		match List.assoc var g with
+    let rec eval (t : term) (g : assignment) (s : store) = match t with
+      Intconstant x -> (Int x, s)
+    | Multiplication (t1, t2) ->
+        (* we don't handle cases where the subterms don't evaluate to Ints *)
+        let (Int i1, s') = eval t1 g s
+        in let (Int i2, s'') = eval t2 g s'
+        (* Multiplication (t1, t2) should evaluate to an Int *)
+        in (Int (i1 * i2), s'')
+    | Addition (t1, t2) ->
+        let (Int i1, s') = eval t1 g s
+        in let (Int i2, s'') = eval t2 g s'
+        in (Int (i1 + i2), s'')
+    | Variable (var) -> ((
+        (* we don't handle cases where g doesn't bind var to any value *)
+        match List.assoc var g with
           | Nonrecursive value -> value
           | Recursive_Closure (self_var, arg_var, body, savedg) as rec_closure ->
-			  (* we update savedg to bind self_var to rec_closure here *)
+              (* we update savedg to bind self_var to rec_closure here *)
               let savedg' = (self_var, rec_closure) :: savedg
               in Closure (arg_var, body, savedg')
-        ), s
-	| Let (var_to_bind, t2, t3) ->
-		(* evaluate t3 under a new assignment where var_to_bind has been bound to
+        ), s)
+    | Let (var_to_bind, t2, t3) ->
+        (* evaluate t3 under a new assignment where var_to_bind has been bound to
            the result of evaluating t2 under the current assignment *)
-		let (value2, s') = eval t2 g s
-		(* we have to wrap value2 in Nonrecursive *)
-		in let g' = (var_to_bind, Nonrecursive value2) :: g
-		in eval t3 g' s'
-	| Iszero (t1) ->
-		(* we don't handle cases where t1 doesn't evaluate to an Int *)
-		let (Int i1, s') = eval t1 g s
-		(* Iszero t1 should evaluate to a Bool *)
-		in (Bool (i1 = 0), s')
-	| If (t1, t2, t3) ->
-		(* we don't handle cases where t1 doesn't evaluate to a boolean *)
-		let (Bool b1, s') = eval t1 g s
+        let (value2, s') = eval t2 g s
+        (* we have to wrap value2 in Nonrecursive *)
+        in let g' = (var_to_bind, Nonrecursive value2) :: g
+        in eval t3 g' s'
+    | Iszero (t1) ->
+        (* we don't handle cases where t1 doesn't evaluate to an Int *)
+        let (Int i1, s') = eval t1 g s
+        (* Iszero t1 should evaluate to a Bool *)
+        in (Bool (i1 = 0), s')
+    | If (t1, t2, t3) ->
+        (* we don't handle cases where t1 doesn't evaluate to a boolean *)
+        let (Bool b1, s') = eval t1 g s
         (* note we thread s' through only one of the then/else clauses *)
-		in if b1 then eval t2 g s'
-		else eval t3 g s'
-	| Makepair (t1, t2) ->
-		let (value1, s') = eval t1 g s
-		in let (value2, s'') = eval t2 g s'
+        in if b1 then eval t2 g s'
+        else eval t3 g s'
+    | Makepair (t1, t2) ->
+        let (value1, s') = eval t1 g s
+        in let (value2, s'') = eval t2 g s'
         (* now we want to retrieve the next free index in s'' *)
         in let new_index = List.length s''
         (* now we want to insert value1 and value2 there; the following is an easy but inefficient way to do it *)
         in let s''' = List.append s'' [value1; value2]
-		in (Pair (new_index, new_index + 1), s''')
-	| First (t1) ->
-		(* we don't handle cases where t1 doesn't evaluate to a Pair *)
-		let (Pair (index1, index2), s') = eval t1 g s
+        in (Pair (new_index, new_index + 1), s''')
+    | First (t1) ->
+        (* we don't handle cases where t1 doesn't evaluate to a Pair *)
+        let (Pair (index1, index2), s') = eval t1 g s
         (* note that s' may be different from s, if t1 itself contained any mutation operations *)
         in (List.nth s' index1, s')
-	| Lambda (arg_var, t2) -> (Closure (arg_var, t2, g), s)
-	| Apply (t1, t2) ->
-		(* we don't handle cases where t1 doesn't evaluate to a function value *)
-		let (Closure (arg_var, body, savedg), s') = eval t1 g s
-		in let (value2, s'') = eval t2 g s'
-		(* evaluate body under savedg, except with arg_var bound to Nonrecursive value2 *)
-		in let savedg' = (arg_var, Nonrecursive value2) :: savedg
-		in eval body savedg' s''
-	| Letrec (var_to_bind, t2, t3) ->
-		(* we don't handle cases where t2 doesn't evaluate to a function value *)
-		let (Closure (arg_var, body, savedg), s') = eval t2 g s
+    | Lambda (arg_var, t2) -> (Closure (arg_var, t2, g), s)
+    | Apply (t1, t2) ->
+        (* we don't handle cases where t1 doesn't evaluate to a function value *)
+        let (Closure (arg_var, body, savedg), s') = eval t1 g s
+        in let (value2, s'') = eval t2 g s'
+        (* evaluate body under savedg, except with arg_var bound to Nonrecursive value2 *)
+        in let savedg' = (arg_var, Nonrecursive value2) :: savedg
+        in eval body savedg' s''
+    | Letrec (var_to_bind, t2, t3) ->
+        (* we don't handle cases where t2 doesn't evaluate to a function value *)
+        let (Closure (arg_var, body, savedg), s') = eval t2 g s
         (* evaluate t3 under a new assignment where var_to_bind has been recursively bound to that function value *) 
-		in let g' = (var_to_bind, Recursive_Closure (var_to_bind, arg_var, body, savedg)) :: g
-		in eval t3 g' s'
+        in let g' = (var_to_bind, Recursive_Closure (var_to_bind, arg_var, body, savedg)) :: g
+        in eval t3 g' s'
     | Setfirst (t1, t2) ->
         (* we don't handle cases where t1 doesn't evaluate to a Pair *)
         let (Pair (index1, index2), s') = eval t1 g s
         (* note that s' may be different from s, if t1 itself contained any mutation operations *)
-        in let (new_value, s'') = eval t2 g s'
-        (* now we create a list which is just like s'' except it has new_value in index1 *)
+        in let (value2, s'') = eval t2 g s'
+        (* now we create a list which is just like s'' except it has value2 in index1 *)
         in let rec replace_nth lst m =
             match lst with
             | [] -> failwith "list too short"
-            | x::xs when m = 0 -> new_value :: xs
+            | x::xs when m = 0 -> value2 :: xs
             | x::xs -> x :: replace_nth xs (m - 1)
         in let s''' = replace_nth s'' index1
         in (Int 42, s''')