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Lambda CalculusA New Approach to Abstract Syntax with Variable BindingPitts and Gabbay, A New Approach to Abstract Syntax with Variable Binding, FAC 2001. In the lambda calculus, the particular choice of variable names  even free variables  is irrelevant. Names serve two purposes:
In a theory of binders, only the latter purpose is relevant. This is why it's so annoying to have to deal with captureavoiding substitution, the Barendregt variable convention,
There are several standard ways to deal with this. Generating fresh names with This paper introduces a theory of fresh names that restores algebraic reasoning, referential transparency, and structural induction to algebraic datatypes with a HOASlike notation for introducing binders into an abstract syntax. This is the settheoretical basis for the authors' work on FreshML and FreshO'Caml, which we've discussed a little bit on LtU in the past. By Dave Herman at 20050314 15:53  Lambda Calculus  MetaProgramming  Theory  7 comments  other blogs  7324 reads
Barbara Partee: Reflections of a Formal Semanticist as of Feb 2005What follows will be a very subjective and personal view, as much my own history and development in the field and how things looked through my eyes as about the development of the field itself. This essay is about natural language semantics, but you'll find old friends here: lambdas, bindings, types, quantifiers etc. If you are lazy, go directly to footnote 25... No surprise, really, if you follow the links we give here from time to time about TLGs and such. By Ehud Lamm at 20050215 10:37  History  Lambda Calculus  Semantics  Type Theory  5 comments  other blogs  8751 reads
The Church Project
http://types.bu.edu or http://www.churchproject.org
We previously linked to a document on this site, but not the site itself. By Andris Birkmanis at 20050208 17:24  Lambda Calculus  Type Theory  3 comments  other blogs  4551 reads
The piCalculus in Direct StyleThe piCalculus in Direct Style
a.k.a. Blue Calculus Normalorder directstyle betaevaluator with syntaxrules, and the repeated applications of call/cc
Oleg's presentation at the workshop in honor of Daniel Friedman is great fun as usual.
The topic of repeated applications of call/cc has been mentioned on LtU previously, a few years
ago. New this time: the full and correct betanormalizer written as a
directstyle syntaxrule. The normalizer implements calculus of
explicit substitutions. The talk presents probably the shortest (and
the fastest) normalorder betanormalizer as a (standalone) Scheme
macro. Another new feature is the discussion of selfapplications of
delimited continuation operators. The talk mentions incidentally that
shift, control, shift0 and other, lessdelimited control operators are the members of the same family: gshift/greset.
Hot stuff. By Ehud Lamm at 20050119 13:07  Lambda Calculus  MetaProgramming  Semantics  1 comment  other blogs  6394 reads
CallbyName, Callby Value and the Lambda Calculus
Gordon Plotkin's
CallbyName, CallbyValue and the Lambda Calculus (Theoretical Computer Science , Vol. 1, pp. 125159, 1975), is available online.
The fundamental point made in the paper should seem natural to most LtU readers: In order to reason about programming language semantics one should look for programming language/calculus pairs. The paper contrasts CBN and CBV, and shows the differences between the Lambda Calculi appropriate for describing each of them. Theoretical Pearl: Church numerals, twice!
Ralf Hinze. Theoretical Pearl: Church numerals, twice! Journal of Functional Programming, 2004. To appear.
This pearl explains Church numerals, twice. The first explanation links Church numerals to Peano numerals via the wellknown encoding of data types in the polymorphic LC. This view suggests that Church numerals are folds in disguise. The second explanation, which is more elaborate, but also more insightful, derives Church numerals from first principles, that is, from an algebraic specification of addition and multiplication. Additionally, we illustrate the use of the parametricity theorem by proving exponentiation as reverse application correct. A simple concept is used to demonstrate several interesting and useful techniques. By Ehud Lamm at 20040715 13:27  Lambda Calculus  login or register to post comments  other blogs  4010 reads
Reflections on reflection  Henk Barendregt(Link)Here's something to exercise both brain hemispheres. Henk Barendregt needs no introduction for many LtU readers  he literally wrote "the book" on the lambda calculus, and that only hints at the profound impact his work has had on lambda calculus and type theory.The page linked above lists two overlapping papers, both about reflection:
As the first paragraph quoted above implies, the scope of these two papers extends far beyond the lambda calculus, into fields such as biology and meditation. Between the two papers, there's something for everyone: "Reflection and its use, from science to meditation" is wideranging, covering reflection related to living cells, formal languages, mathematics, art, computers, and the human mind. "Reflection and its use, with an emphasis on languages and lambda calculus", focuses specifically on reflection in formal languages, including combinatory logic and lambda calculus.
By Anton van Straaten at 20040713 16:32  Fun  General  Lambda Calculus  login or register to post comments  other blogs  10501 reads

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