tweak calc improvements

Signed-off-by: Jim Pryor <profjim@jimpryor.net>

diff --git a/advanced_topics/calculator_improvements.mdwn b/advanced_topics/calculator_improvements.mdwn
index 4f24f87..cbf4c89 100644 (file)
--- a/advanced_topics/calculator_improvements.mdwn
+++ b/advanced_topics/calculator_improvements.mdwn
@@ -145,9 +145,9 @@ Now our evaluation function needs two further clauses to interpret the two new e
        ...
        | Lambda(arg_var, t1) -> Closure (arg_var, t1, g)
        | Apply(t1, t2) ->
-               let value2 = eval t2 g
                (* we don't handle cases where t1 doesn't evaluate to a function value *)
-               in let Closure (arg_var, body, savedg) = eval t1 g
+               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';;
@@ -276,9 +276,9 @@ Since we're not permitting ourselves OCaml's ability to recursively define cycli
        ...
        | Lambda(arg_var, t1) -> Closure (arg_var, t1, g)
        | Apply(t1, t2) ->
-               let value2 = eval t2 g
                (* we don't handle cases where t1 doesn't evaluate to a function value *)
-               in let Closure (arg_var, body, savedg) = eval t1 g
+               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 Nonrecursive value2 *)
                in let savedg' = (arg_var, Nonrecursive value2) :: savedg
                in eval body savedg'