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Functional Programming For Dynamic Programmers - Part 4
=======================================================
:author: Michele Simionato
:date: December 2007
This is the fourth of a series of articles on functional programming in
statically typed languages. It is intended for dynamic programmers, i.e.
for programmers with a background in dynamically typed languages, such as Perl,
Python, Ruby, or languages in the Lisp family. The approch is eminently practical
and example-based; the main goal is to see if we can stole some good idea from
statically typed languages. In order to be concrete, I will consider languages
in the ML family, because they are pretty nice and much easier to understand
that Haskell.
Text processing in SML
----------------------------------------------
Scripting languages, starting from Perl, have a very strong tradition
in the field of text processing. In comparison, SML has very few
primitive text processing functions. Still, it is not difficult to implement a few
basic facilities. In this assessment, as a learning exercise, I will
show how can implement a simple template mechanism. In order to do
so, the first thing to discuss is the regular expression. More or
less all SML implementations have they own regular expression library;
here I will consider only Alice ML library, which is very simple and
needs to be supplemented by some utility in order to become usable.
$pippo:
$hello
$are pippo lippo
fun pippo {hello, are} = "" ^ hello ^ "" ^ are " pippo lippo"
link:<a href="$u">$a</a>
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