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Date: Wed, 8 Sep 1993 12:04:10 -0400
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From: "Vincent Maiorana" <[EMAIL PROTECTED]>
To: haskers
Subject: Dec_1991_docs
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Sirs:
I have three short questions prompted by my
reading of HASKELL, Version 1.2beta, December 1991.
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Question 1
Could you describe (or point to a page that describes)
what is meant by the notation on page 83:
-- constant function
const :: a -> b -> a
const x _ = x
With a copy of Winston/Horn's discussion of Lambda calculus
in hand, (and I've almost located a paper by Church),
I do not understand the :: a -> b -> a
expression. Help !
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Question 2
Could you provide a simple glossary of mathematical notations
in the next versions of the docs?
It took a while for me to realize that the => symbol meant
if p then q (p only if q) a.k.a the 'context operator'
Question 2a:
Could you provide an English definition of
"expression type signature" versus "type signature".
Are they one-in-the-same? I could not find an adequate
English definition that distinguished the two.
F Y I C O M M E N T S:
o The industry language MHDL (based on HASKELL)
never defined the => operator! C++ literature
does a somewhat better job of defining type defintion
and class definitions of types.
o Perhaps the HASKELL docs could follow the formats of
introductory (and later in HASKELL) advanced C++ docs.
See Lippman's C++ or other "primers" for an idea.
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Question 3
Could you explain (or point to an explanation) of the Lambda
production (page 10)
exp 10 -> \apat .. apatn -> exp
and how it relates to Winston/Horn's discussion of Lambda
in their LISP book, chapter 6, "Definition of Lambda"?
It seems as if the backslant is a LITERAL part of the syntax.
If that is the case, BNF formatting rules usually require
a '\' as the designation of a literal.
Thanks !
Vincent Maiorana
Raytheon Company
Missile System Division
Computer Aided Engineering
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