From: Jim Pryor <profjim@jimpryor.net>
Date: Sat, 4 Dec 2010 15:25:36 +0000 (-0500)
Subject: translating tweaks
X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=commitdiff_plain;h=7d1a4657f55750d3eb1571a498573cf0faada29c

translating tweaks

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

diff --git a/translating_between_OCaml_Scheme_and_Haskell.mdwn b/translating_between_OCaml_Scheme_and_Haskell.mdwn
index ea4079e9..4b0f7154 100644
--- a/translating_between_OCaml_Scheme_and_Haskell.mdwn
+++ b/translating_between_OCaml_Scheme_and_Haskell.mdwn
@@ -42,14 +42,17 @@ Additionally, the syntax of OCaml and SML is superficially much closer to Haskel
 
 *	**Type Variants and Pattern Matching** If you want to reproduce this kind of OCaml code:
 
-		type lambda_expression = Var of char | Lam of char * lambda_expression | App of lambda_expression * lambda_expression;;
+		# type lambda_expression = Var of char | Lam of char * lambda_expression | App of lambda_expression * lambda_expression;;
 
-		let rec free_vars (expr : lambda_expression) : char list =
+		# let rec free_vars (expr : lambda_expression) : char list =
 		  match expr with
 		    | Var label -> [label]
 		    | Lam (label, body) -> remove label (free_vars body)
 		    | App (left, right) -> merge (free_vars left) (free_vars right);;
 
+		# free_vars (Lam ('x', (App (Var 'x', Var 'y'))));;
+		- : char list = ['y']
+
 	in Scheme, you have two choices. First, the quick hack:
 
 		; we use the symbols 'var and 'lam as tags, and assume
@@ -85,6 +88,8 @@ Additionally, the syntax of OCaml and SML is superficially much closer to Haskel
 		    (lam (label body) (remove label (free-vars body)))
 		    (app (left right) (remove-duplicates (append (free-vars left) (free-vars right))))))
 
+		(free-vars (lam 'x (app (var 'x) (var 'y))))
+		; evaluates to '(y)
 
 *	Scheme has excellent support for working with implicit or "first-class" **continuations**, using either `call/cc` or any of various delimited continuation operators. See <http://docs.racket-lang.org/reference/cont.html?q=shift&q=do#%28part._.Classical_.Control_.Operators%29>.