Recursively generating the look-and-say sequence. Viewed 579 times 5. Typical actions include reading and setting global variables, writing files, reading input, and opening windows. The legendary John H. Conway on properties he discovered within the so-called Look-and-Say Sequence. Puzzles. For example, "1" becomes "11", because there is one "1". You could argue that Haskell has a much better form of duck typing. 3 -> 13, 33 -> 23, 12 -> 1112 -> 3112. tags: haskell monads list. The sequence is obtained continuously by applying the look-and-say rule from seed 2: 2 -> 1,2 -> 1,1,1,2 -> etc. You simply ‘look-and-say’. The “Look and Say” sequence, Sloane number A005150, begins 1, 11, 21, 1211, 111221, 312211, 13112221, 1113213211, …. The look-and-say sequence (which I talked about here) is the sequence that you get by starting with the number 1 and constructing the next term in the sequence by “reading” the previous term.So 1 becomes “one one”, or 11. So: 1) The look-and-say-sequence does not depend much on the chosen base, with one important restriction: Much of the regularity in the behavior relies on the fact that no other number than $1,2,3$ can appear in the sequence. Nth element of Look-And-Say sequence in Haskell. Print the first 20 elements of the Look and Say sequence. 0 characters ARGV is available via STDIN, joined on NULL. The Look & Say sequence is quite ea s y to understand. The Look-and-Say Sequence with Digits 1 and 2. newSequence newValue oldSequence = Sequence.update 3000 newValue oldSequence will produce a new sequence with a newValue for in the place of its 3000 element. I explained it to my dog in about 10 seconds and she stayed focused the entire time. The look and say sequence, invented by mathematician John Conway and popularized by Robert Morris, is also known as "count and say sequence" or "say what you see sequence". the output sequence would be 23211435.1 Thus the resulting sequences are also sometimes called “look and say” sequences. The 2nd term is 11 ('one one') because the first term (1) consisted of a single 1. It is one of the more popular functional languages, and the lazy functional language on which the most research is being performed. See the list of supported languages to know the extension of your language.. raw download clone embed report print Haskell 0.79 KB. I would like to introduce look-and-say sequence at first. We calculated the look and say sequence in a previous exercise, and mentioned there that the sequence has some fascinating mathematical properties.One of them is that, if L n is the number of digits in the n-th element of the sequence, then. The look-and-say sequence is the sequence of below integers: 1, 11, 21, 1211, 111221, 312211, 13112221, 1113213211, … How is above sequence generated? The sequence starts plainly with a single digit 1: 1. That becomes “two ones”, or 21. A Look and Say sequence is an integer sequence in which a term is obtained by writing down a verbal description of the previous term. The Haskell code will represent these sequences as lists of type [Int] all of the members of which are positive.2 (In this paper, the elements of a list will be In this section, we look at several aspects of functions in Haskell. Active 2 years, 3 months ago. The Look and say sequence is a recursively defined sequence of numbers studied most notably by John Conway. 5 kyu. The look-and-say sequence is the sequence of numbers generated by describing each number to produce the next. The Look and Say sequence starts with 1 and is continued by looking at each of the runs of the same number in the previous element and combining the length with the original number. The digits 1, 2 and 3 can (and unless starting with 22, all eventually must) appear as the number of digits of a group at the previous stage, e.g. For example the next element after 111221 would be 312211 (three ones, two twos and one one). Getting started Exercise 1 What is the largest possible value of type Int on the computer you are using? Starting with 1 the sequence would be read out loud as 1 one 1 two 1s one 2 one 1 and so forth and the result is 1 11 21 1211 111221 … . Haskell will look at how you use the variables and figure out from there what type the variable should be - then it will all be type-checked to ensure there are no type-mismatches. The sequence is then determined by pairs of digits. The first few numbers are 1, 11, 21, 1211, 111221, 312211 and 13112221. a guest Mar 30th, 2015 286 Never Not a member of Pastebin yet? Haskell Java JavaScript PHP Python Ruby. If you use emacs I recommend installing Intero (https: //commercialhaskell.github.io/intero/). Look-and-say sequence starts from a string of characters (digits or/and letters) and works as follows – you look at the current symbol and count its frequency. Look and Say Sequence (Conway’s constant) Matz August 9, 2014 - 1:16 am January 26, 2015 Math, Programming. Find the n’th term in Look-and-say (Or Count and Say) Sequence. In Haskell, there are several ways to handle data that is structured in this way. Haskell is a standardized purely functional programming language with non-strict semantics, named after the logician Haskell Curry. I don't really understand the where clause but that does not work :( permalink 38 38 7 88% of 94 714 kyushiro 2 Issues Reported. 5 kyu . The look-and-say sequence is such a sequence that for creating each term of this sequence you have to read a number alphabetically and then write that alphabetic readings numerically. The 3rd term is then 21 ('two one') because the second term consisted of two 1s. We look at this and say what we see. We've had a few challenges involving the Look-and-say sequence. Simple Fun #299: Look And Say And Sum. //atom-haskell.github.io/ to get set up), TextMate, and Sub-lime Text. 6 kyu. In this view, a calculation with a list is a calculation that is uncertain about the result. 1 = one 1 (so = 11) 11 = two 1 (so = 21) 21 = one 2 one 1 (so = 1211) As a rule of the sequence, no number can go beyond 3, so creating a translation table can fit in. The rules are as follows: Take any number you like. Problem. More precisely, I want to look at a few different binary number systems (i.e. Print out the first 12 terms of the look-and-say sequence … 38 38 11 95% of 143 453 GiacomoSorbi. For example the term 11222 would be read as two 1s three 2s so the next term would be 2132. 5 kyu. Now we have come to the list monad, and now it gets interesting. The I/O system in Haskell is purely functional, yet has all of the expressive power found in conventional programming languages. Python has the notion of "duck typing", meaning "If it walks and talks like a duck, it's a duck!". Arrays. The idea of the look-and-say sequence is similar to that of run-length encoding. Sign Up, it unlocks many cool features! A225224 and A221646 are from seed 1 and A088204 from seed 3. In other words, the UID is a key into a database. How do you know? The Look and Say sequence. That is: look-and-say is like Fibonacci, just with 92 instead of 2. Because in the world of haskell, a list is a collection of results from a calculation that could be zero, one or several elements. Generalizing fold. The sequence starts with the number 1 and each additional number encodes the number of digits that are repeated before each digit sequence. Again, it doesn't destroy the old sequence, it just creates a new one. The value is architecture-dependent, so don’t just Google it—ﬁnd out empiri-cally. If we start with any digit d from 0 to 9 then d will remain indefinitely as the last digit of the sequence. The first few numbers are 1, 11, 21, 1211, and 111221.The next number in the sequence is 312211, because the last one has "Three 1s, two 2s, and one 1".Given n, produce the n-th number in the sequence.The output will not be longer than 20,000 characters. You don’t need any mathematical background and little thought is required to find the next term. The n-th term is constructed by reading the (n-1)-th term. Audrey … I just took a look at John Conway’s video at Numberphile about the “look-and-say” sequence or as Conway called it “The Weird and Wonderful Chemistry of Audioactive Decay”. Language is selected by the extension of the file. Hardy's taxi (generalized) 9 9 0 90% of 20 59 jakber. 16 16 8 85% of 62 170 myjinxin2015. n’th term in generated by reading (n-1)’th term. Each term is constructed from its predecessor by stating the frequency and number of each group of like digits. Algorithms. Terms of even ranks are counts while odd ranks are figures. The Look and Say sequence is an interesting sequence of numbers where each term is given by describing the makeup of the previous term. First, consider this definition of a function which adds its two arguments: add :: Integer -> Integer -> Integer add x y = x + y This is an example of a curried function. The look-and-say sequence was introduced and analyzed by John Conway. The statement is not trivial, as the sequence is a sequence of numbers, each of which can have many digits, and it speaks about what new digits can appear in numbers as the sequence develops. In imperative languages, programs proceed via actions which examine and modify the current state of the world. Closely related to the ternary version of the sequence is the sequence obtained by reading the previous term in the sequence, but with the restriction that you can never use a number larger than 2 (see A110393). Since Haskell is a functional language, one would expect functions to play a major role, and indeed they do. However, this is still true for any base $\geq 4$. In this post I want to look at what happens with different number systems. These users have contributed to this kata: Similar Kata: 6 kyu. number systems using only two bits 0 and 1 instead of the usual ten digits 0,1,..,9). Look and say sequence generator. The look and say sequence is a basic form of run length encoding. Mathematics. Quick reminder: The sequence starts with 1, Subsequent terms of this sequence are generated by enumerating each group … Rules for Creating the Sequence . For example, if you look at "22a", you count "two twos" and "one a" so the next sequence element is "221a", and then you repeat this process. That is, “I can see one one”. The value of this list lies in being able to look up a textual username for a given UID, not in the order of the data. It's generated by describing a series of digits as letters in plain English language. The 1st term is given as 1. But it is not semantic, I don't like it. The two most common are association lists and the Map type provided by Data.Map module. The Look and Say sequence. The look-and-say sequence above makes use of the standard decimal system to translate the numbers one, two, and three to their usual digits. You can take any number as a starting number, and then follow this rule to produce next numbers. That becomes “one two, one one”, or 1211, and so on. Why? Although Haskell has a comparatively small user community, its strengths have been well applied to a few projects. The list in haskell is viewed as a monad. Yes, I didn't know it was called a look-and-say sequence, but that's what I'm trying to do. Numbers. The system is it checks the previous digit and counts the numbers. 4 4 1 86% of 21 60 haspience. Ask Question Asked 2 years, 3 months ago. Train Next Kata. Then "11" becomes "21", and so on. For instance, the term after 1211 is “one 1, one 2, and two 1s”, or 111221. The look-and-say sequence is also known as the Morris Number Sequence, after cryptographer Robert Morris, and the puzzle What is the next number in the sequence 1, 11, 21, 1211, 111221? Sequences. All Langs ><> Bash brainfuck C C# COBOL F# Fortran Go Haskell J Java JavaScript Julia Lisp Lua Nim Perl PHP PowerShell Python Raku Ruby Rust SQL Swift V Zig. The beauty of the look-and-say sequence is how simple it is to define. Association lists are handy because they are simple. One two, one one ”, or 111221 to do viewed as a starting number and! 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