RE: Implementation 4

From: Rui Shi (shearer@cs.bu.edu)
Date: Mon Nov 27 2006 - 13:04:16 EST 

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From: "Rui Shi" <shearer@cs.bu.edu>
To: <samepst@cs.bu.edu>
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Subject: RE: Implementation 4
Date: Mon, 27 Nov 2006 13:04:16 -0500
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Hi,

I didn't see the point of the change. From my point of view, "TpUni of int"
is sufficient for the purpose.

In fact, to represent universal type scheme, you don't need to have explicit
qualifiers as implied by your proposed changes. For instance

let f = lam y => y in (f 10, f true)

when you do the constraint generation, f's type can be (TpUni 1 -> TpUni 1)
which is equivalent to \forall a. a -> a.

Hope that is helpful.

- Rui

-----Original Message-----
From: samepst@cs.bu.edu [mailto:samepst@cs.bu.edu]
Sent: Monday, November 27, 2006 12:44 PM
To: shearer@cs.bu.edu
Subject: Implementation 4

Hello,

I had to make a few changes to the framework of programming assignment 4 to
implement the let-polymorphism using type scheme. I changed:

TpUni of int

to

TpScheme of int list * stp

is this acceptable?

Thanks,
-Sam

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