X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=blobdiff_plain;f=code%2Funtyped_evaluator.ml;h=5ccecb50296b578f490b590f10dc97f85ec984a4;hp=edfc6ee3804898e3f180f4e837a3b4a69d0dd604;hb=30e80630a4bdb0ec23dd7098f735b060f6a3de0f;hpb=fd72a947c60f0178c7464b68b922b72ffe530bf7

diff --git a/code/untyped_evaluator.ml b/code/untyped_evaluator.ml
index edfc6ee3..5ccecb50 100644
--- a/code/untyped_evaluator.ml
+++ b/code/untyped_evaluator.ml
@@ -1,5 +1,5 @@
 (*
-   This is a simplified version of the code at ...
+   This is a simplified version of the code at http://lambda.jimpryor.net/code/untyped_full-1.7.tgz
    You can use this code as follows:
 
    1. First, use a text editor to fill in the (* COMPLETE THIS *) portions.
@@ -15,7 +15,7 @@
       `reduce (App(Lambda("x",Var "x"),Lambda("y",Var "y")))`
       `evaluate (App(Lambda("x",Var "x"),Lambda("y",Var "y")))`
 
-   The two interpreters presented below are (VersionA) a substitute-and-replace
+   The two interpreters presented below are (VersionA) a substitute-and-repeat
    interpreter, and (VersionB) an environment-based interpreter. We discuss the
    differences between these in the course notes.
 
@@ -61,7 +61,7 @@ and env = (identifier * term) list
 (* Operations for environments *)
 let empty = []
 let shift (ident : identifier) binding env = (ident,binding) :: env
-let rec lookup (sought_ident : ident) (env : env) : term option =
+let rec lookup (sought_ident : identifier) (env : env) : term option =
   match env with
   | [] -> None
   | (ident, binding) :: _ when ident = sought_ident -> Some binding
@@ -72,7 +72,7 @@ let rec lookup (sought_ident : ident) (env : env) : term option =
    eval raises this exception when it fails to reduce/evaluate
    a term, because it has components for which no
    reduction/evaluation is defined, such as `x y`. The
-   reduction-based interpreter just signals this with a normal
+   substitute-and-repeat interpreter just signals this with a normal
    return value; but the environment-based interpreter uses an
    exception to abort prematurely.