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Today's Topics:
1. Basic Trie Implementation: Request for Feedback and
QuickCheck Question (Dominik Bollmann)
----------------------------------------------------------------------
Message: 1
Date: Sat, 27 Aug 2016 15:00:43 +0200
From: Dominik Bollmann <[email protected]>
To: [email protected]
Subject: [Haskell-beginners] Basic Trie Implementation: Request for
Feedback and QuickCheck Question
Message-ID:
<87vaymnz7o.fsf@t450s.i-did-not-set--mail-host-address--so-tickle-me>
Content-Type: text/plain
Hello Haskellers,
I just finished implementing a very simple Trie module, consisting of a
Trie data type as well as operations `insert` and `lookup`. Function
`insert` inserts a new element into the Trie; function lookup searches
for all words in the Trie that match a specific pattern. Besides regular
words, a pattern may consist of a single dot '.', indicating that at
this position of the search term any letter may occur. For example a
pattern "hello" would just search for the word "hello" in the Trie,
while ".ello" would search words starting in *any* letter and followed
by the sequence "ello" (i.e., it searches for "hello", "Hello", "Aello",
etc.)
The code for the Trie module can be found here: http://lpaste.net/180768.
Regarding the code I have two questions:
(1) Since I'm new to Haskell, I'd very much welcome feedback on the
general implementation of the Trie module and its two methods what
I could improve.
(2) While testing the Trie module with QuickCheck, I wrote the
property `prop_insert_then_lookup_succeeds` stating that after
inserting a word into a Trie it can always successfully be looked
up again. While quickchecking this property seems to succeed, I
cannot verbose check it. In particular, when I run
`verboseCheck prop_insert_then_lookup_succeeds`
this property consumes all my main memory and results in the
program hanging.
Does anyone know what I messed up in devising the quickcheck
property? I guess I left open some memory leak... Maybe it has to
to with the Arbitrary instance which I might have defined
incorrectly?
Responses to any of the two questions above are very welcome :-)
Thanks!
Dominik.
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