X-Git-Url: http://git.megacz.com/?p=coinductive-monad.git;a=blobdiff_plain;f=Computation%2FEval.v;fp=Computation%2FEval.v;h=07d79e4d104a8df9b9e0a364820dbd4b0f78f704;hp=0000000000000000000000000000000000000000;hb=ad8905d391e4e2015b6525a81a3b5e1ad607439e;hpb=7439e43c33a10817e19e7a5f26435d2097dc262d

diff --git a/Computation/Eval.v b/Computation/Eval.v
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+Require Export Computation.Monad.
+Require Export Computation.Termination.
+
+(* evaluate up to [n] computation steps *)
+Fixpoint bounded_eval (A:Set) (n:nat) (c:#A) {struct n} : option A :=
+  match n with
+    | O      => None
+    | (S n') =>
+      match c with
+        | Return b   => Some b
+        | Bind _ f c' =>
+          match (bounded_eval _ n' c') with
+            | None   => None
+            | Some a => bounded_eval A n' (f a)
+          end
+      end
+  end.
+
+Inductive Unit : Set := unit : Unit.
+Definition eval (A:Set) (c:#A) (t:Terminates c) : A :=
+  match eval' c Unit (Return unit) (termination_is_safe A c t) with
+    | exist x pf => x
+  end.
+
+Implicit Arguments eval [A].
+Implicit Arguments bounded_eval [A].