X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=blobdiff_plain;f=translating_between_OCaml_Scheme_and_Haskell.mdwn;h=4b0f715432c96dff25a2eed522f92bb7adcc985a;hp=891490227c87c2b3ca7c3d567774d70f8bf74d33;hb=7d1a4657f55750d3eb1571a498573cf0faada29c;hpb=9e19c6911155ccdac50589b6f16e53a8953451b4

diff --git a/translating_between_OCaml_Scheme_and_Haskell.mdwn b/translating_between_OCaml_Scheme_and_Haskell.mdwn
index 89149022..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>.
 
@@ -145,8 +150,7 @@ We will however try to give some general advice about how to translate between O
 
 *	In Haskell, you say a value has a certain type with: `value :: type`. You express the operation of prepending a new `int` to a list of `int`s with `1 : other_numbers`. In OCaml it's the reverse: you say `value : type` and `1 :: other_numbers`.
 
-*	In Haskell, type names and constructors both begin with capital letters, and type variables always appear after their constructors, in Curried form. And the primary term for declaring a new type is `data` (short for "abstract datatype").
-So we have:
+*	In Haskell, type names and constructors both begin with capital letters, and type variables always appear after their constructors, in Curried form. And the primary term for declaring a new type is `data` (short for [[!wikipedia algebraic data type]]). So we have:
 
 		data Either a b = Left a | Right b;
 		data FooType a b = Foo_constructor1 a b | Foo_constructor2 a b;