From 8e24378981bd4095fe580475cf6a530e168965b1 Mon Sep 17 00:00:00 2001 From: Jim Pryor Date: Sat, 4 Dec 2010 18:31:41 -0500 Subject: [PATCH] translating tweaks Signed-off-by: Jim Pryor --- translating_between_OCaml_Scheme_and_Haskell.mdwn | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/translating_between_OCaml_Scheme_and_Haskell.mdwn b/translating_between_OCaml_Scheme_and_Haskell.mdwn index d0f7442c..b8938962 100644 --- a/translating_between_OCaml_Scheme_and_Haskell.mdwn +++ b/translating_between_OCaml_Scheme_and_Haskell.mdwn @@ -183,15 +183,17 @@ We will however try to give some general advice about how to translate between O type Weight = Integer type Person = (Name, Address) -- supposing types Name and Address to be declared elsewhere - then you can use a value of type `Integer` wherever a `Weight` is expected, and vice versa. `newtype` and `data` on the other hand, create genuinely new types. `newtype` is basically just an efficient version of `data` that you can use in special circumstances. `newtype` must always take one type argument and have one value constructor. For example: + then you can use a value of type `Integer` wherever a `Weight` is expected, and vice versa. + + `newtype` and `data` on the other hand, create genuinely new types. `newtype` is basically just an efficient version of `data` that you can use in special circumstances. `newtype` must always take one type argument and have one value constructor. For example: newtype PersonalData a = PD a You could also say: - data PersonalData a = PD a + data PersonalData2 a = PD2 a - And `data` also allows multiple type arguments, and multiple variants and value constructors. + And `data` also allows multiple type arguments, and multiple variants and value constructors. OCaml just uses the one keyword `type` for all of these purposes: @@ -201,7 +203,7 @@ We will however try to give some general advice about how to translate between O * When a type only has a single variant, as with PersonalData, Haskell programmers will often use the same name for both the type and the value constructor, like this: - data PersonalData a = PersonalData a + data PersonalData3 a = PersonalData3 a The interpreter can always tell from the context when you're using the type name and when you're using the value constructor. -- 2.11.0