RE: Abstract Interpretation of XSLT stylesheets

[Dylan Walsh <Dylan.Walsh@xxxxxxxxxx>]

From:	Kay Michael [SMTP:Michael.Kay@xxxxxxx]
Sent:	Thursday, July 06, 2000 9:47 AM
To:	'xsl-list@xxxxxxxxxxxxxxxx'
Subject:	RE: Abstract Interpretation of  XSLT stylesheets

>> XSLT is a declarative language, not a functional language. Think SQL.
>
>I think that's open to debate.

Functional programming is a subset of declarative programming. From the
FOLDOC computing dictionary:
http://wombat.doc.ic.ac.uk/foldoc/

"declarative language

A general term for a relational language or a functional language, as
opposed to an imperative language. Imperative (or procedural) languages
specify explicit sequences of steps to follow to produce a result, while
declarative languages describe relationships between variables in terms of
functions or inference rules and the language executor (interpreter or
compiler) applies some fixed algorithm to these relations to produce a
result. The most common examples of declarative languages are logic
programming languages such as Prolog and functional languages like Haskell."

And on FP:

"functional programming

A program in a functional language consists of a set of (possibly recursive)
function definitions and an expression whose value is output as the
program's result. Functional languages are one kind of declarative language.
They are based on the typed lambda-calculus with constants. There are no
side-effects to expression evaluation so an expression (e.g. a function
applied to certain arguments) will always evaluate to the same value (if its
evaluation terminates). Furthermore, an expression can always be replaced by
its value without changing the overall result (referential transparency). "



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