AppendicesnotesresearchAnansi’s WifeAnansi’s Family and OriginsAn interesting retelling of the “box of stories” myth, which is also the ‘pot of wisdowm” myth:Anansi and the Box of StoriesAnansi is the child of the godly manifestations of his mother the Earth (Asaase Yaa) and his father the Sky (Nyame), so is a true representation of all things on heaven and earth. He has many children with his wife Aso, but the most notable child is Ntikuma, a boy who plays a significant part in one of the more popular legends, regarding the bringing of wisdom to the world.–Anansi : Mythology.net ...继续阅读 (30)

Thor’s Law describes the behaviour of coftware engineers in a social medium. Thor’s Law states:As the length of a discussion about software design increases, the probability of someone mentioning aGeneral-purpose tool-building factory factory factoryapproaches one.The self-referential corollary to Thor’s Law states:Including the act of quoting Thor’s Law. ...继续阅读 (31)

Thor’s Law describes the behaviour of coftware engineers in a social medium. Thor’s Law states:As the length of a discussion about software design increases, the probability of someone mentioning aGeneral-purpose tool-building factory factory factoryapproaches one.The self-referential corollary to Thor’s Law states:Including the act of quoting Thor’s Law. ...继续阅读 (28)

Preface (2023)The following described the cryptographic protocol and algorithm used bynCrypt Lightback in 1993-94. I wrote nCrypt Light in the hope of creating a strong cryptography app for the orginalNewton MessagePad 100. Rolling your own crypto is well-understood to be the complete opposite of implementing secure cryptography, so this is presented purely for nostalgia and amusement purposes.The MessagePad at that time had messaging and email if connected to a network of some kind, but it did not have strong, secure protocol for ensuring the privacy of messages or documents. My business part ...继续阅读 (23)

Preface (2023)The following described the cryptographic protocol and algorithm used bynCrypt Lightback in 1993-94. I wrote nCrypt Light in the hope of creating a strong cryptography app for the orginalNewton MessagePad 100. Rolling your own crypto is well-understood to be the complete opposite of implementing secure cryptography, so this is presented purely for nostalgia and amusement purposes.The MessagePad at that time had messaging and email if connected to a network of some kind, but it did not have strong, secure protocol for ensuring the privacy of messages or documents. My business part ...继续阅读 (28)

This is not a programming post.loanwordsAloanwordis a term taken from another language and used without translation; it has a specific meaning that (typically) does not otherwise exist in a single English word. Sometimes the word’s spelling or pronunciation (or both) is slightly altered to accommodate English orthography, but, in most cases, it is preserved in its original language.Résumé(🇫🇷) andkindergarten(🇩🇪) are loanwords.calquesAcalque, on the other hand, is a word or phrase taken from another language but translated (either in part or in whole) to corresponding English words while still ...继续阅读 (25)

This is not a programming post.loanwordsAloanwordis a term taken from another language and used without translation; it has a specific meaning that (typically) does not otherwise exist in a single English word. Sometimes the word’s spelling or pronunciation (or both) is slightly altered to accommodate English orthography, but, in most cases, it is preserved in its original language.Résumé(🇫🇷) andkindergarten(🇩🇪) are loanwords.calquesAcalque, on the other hand, is a word or phrase taken from another language but translated (either in part or in whole) to corresponding English words while still ...继续阅读 (27)

In software development, we talk a lot about software anti-patterns, how to recognize them, and how to extricate yourself from them via refactoring.Ananti-patternis a common response to a recurring problem that is usually ineffective and risks being highly counterproductive. The term, coined in 1995 by computer programmerAndrew Koening, was inspired by the bookDesign Patterns, which highlights a number of design patterns in software development that its authors considered to be highly reliable and effective.The term was popularized three years later by the bookAntiPatterns, which extended its ...继续阅读 (24)

In software development, we talk a lot about software anti-patterns, how to recognize them, and how to extricate yourself from them via refactoring.Ananti-patternis a common response to a recurring problem that is usually ineffective and risks being highly counterproductive. The term, coined in 1995 by computer programmerAndrew Koening, was inspired by the bookDesign Patterns, which highlights a number of design patterns in software development that its authors considered to be highly reliable and effective.The term was popularized three years later by the bookAntiPatterns, which extended its ...继续阅读 (22)

In the board gameMouse Trap, players build an elaborateRube Goldberg Machine. Wikipedia explains:The player turns the crank (A) which rotates the gears (B) causing the lever (C) to move and push the stop sign against the shoe (D), which tips the bucket holding the metal ball (E) which rolls down the stairs (F) and into the pipe (G) which leads it to hit the rod held by the hands (H), causing the bowling ball (I) to fall from the top of the rod, roll down the groove (J), fall into and then out of the bottom of the bathtub (K), landing on the diving board (L). The weight of the bowling ball cata ...继续阅读 (28)

In this essay, we’re going to work withinvertible functions. A function is invertible if it has aninverse function. Consider:constevenToNatural=even=>even/2;constnaturalToEven=natural=>natural*2;evenToNaturalandnaturalToEvenareinversesof each other:evenToNatural(14)//=> 7naturalToEven(7)//=> 14Which is to say, each function inverts or reverses the computation of the other function. This implies that for alln ∈ N:n===evenToNatural(naturalToEven(n))&&n;===naturalToEven(evenToNatural(n))And, subject to JavaScript’s implementation limitations, this expression istrue.1A functionfis consideredinvert ...继续阅读 (44)

On April 8, 2020,John Horton Conwaydeveloped symptoms of COVID-19. On April 11, 2020, he succumbed to the disease.1234Like so very, very many, I mourn Conway’s passing, and yet I also celebrate his life. I celebrate his accomplishments, I celebrate his curiosity, and I celebrate his skill at making important topics in mathematics engaging and interesting.One of the finest examples of that skill is the programming language FRACTRAN, the subject of this essay.PreludeJohn Horton Conway in 1993Conway touched my own life from early days. As I described inThe Eight Queens Problem… and Raganwald’s Un ...继续阅读 (112)

On April 8, 2020,John Horton Conwaydeveloped symptoms of COVID-19. On April 11, 2020, he succumbed to the disease.1234Like so very, very many, I mourn Conway’s passing, and yet I also celebrate his life. I celebrate his accomplishments, I celebrate his curiosity, and I celebrate his skill at making important topics in mathematics engaging and interesting.One of the finest examples of that skill is the programming language FRACTRAN, the subject of this essay.PreludeJohn Horton Conway in 1993Conway touched my own life from early days. As I described inThe Eight Queens Problem… and Raganwald’s Un ...继续阅读 (24)

This is Part II of “Exploring Regular Expressions.” If you haven’t already, you may want to readPart Ifirst, where we wrote a compiler that translatesformal regular expressionsintofinite-state recognizers.You may also want another look at the essay,A Brutal Look at Balanced Parentheses, Computing Machines, and Pushdown Automata. It covers the concepts behind finite-state machines and the the kinds of “languages” they can and cannot recognize.Table of ContentsThe Essentials from Part IRegular ExpressionsOur Code So Farthe shunting yardthe stack machineevaluating arithmetic expressionscompiling ...继续阅读 (28)

This is Part II of “Exploring Regular Expressions.” If you haven’t already, you may want to readPart Ifirst, where we wrote a compiler that translatesformal regular expressionsintofinite-state recognizers.You may also want another look at the essay,A Brutal Look at Balanced Parentheses, Computing Machines, and Pushdown Automata. It covers the concepts behind finite-state machines and the the kinds of “languages” they can and cannot recognize.Table of ContentsThe Essentials from Part IRegular ExpressionsOur Code So Farthe shunting yardthe stack machineevaluating arithmetic expressionscompiling ...继续阅读 (26)

PreludeIn this essay, we’re going to explore regular expressions by implementing regular expressions.This essay will be of interest to anyone who would like a refresher on the fundamentals of regular expressions and pattern matching. It is not intended as a practical “how-to” for using modern regexen, but the exercise of implementing basic regular expressions is a terrific foundation for understanding how to use and optimize regular expressions in production code.As we develop our implementation, we will demonstrate a number of important results concerning regular expressions, regular language ...继续阅读 (27)

PreludeIn this essay, we’re going to explore regular expressions by implementing regular expressions.This essay will be of interest to anyone who would like a refresher on the fundamentals of regular expressions and pattern matching. It is not intended as a practical “how-to” for using modern regexen, but the exercise of implementing basic regular expressions is a terrific foundation for understanding how to use and optimize regular expressions in production code.As we develop our implementation, we will demonstrate a number of important results concerning regular expressions, regular language ...继续阅读 (26)

As discussed inPattern Matching and Recursion, a well-known programming puzzle is to write a function that determines whether a string of parentheses is “balanced,” i.e. each opening parenthesis has a corresponding closing parenthesis, and the parentheses are properly nested.For example:InputOutputComment''truethe empty string is balanced'()'true'(())'trueparentheses can nest'()()'truemultiple pairs are acceptable'(()()())()'truemultiple pairs can nest'((()'falsemissing closing parentheses'()))'falsemissing opening parentheses')('falseclose before openThis problem is amenable to all sorts of s ...继续阅读 (64)

As discussed inPattern Matching and Recursion, a well-known programming puzzle is to write a function that determines whether a string of parentheses is “balanced,” i.e. each opening parenthesis has a corresponding closing parenthesis, and the parentheses are properly nested.For example:InputOutputComment''truethe empty string is balanced'()'true'(())'trueparentheses can nest'()()'truemultiple pairs are acceptable'(()()())()'truemultiple pairs can nest'((()'falsemissing closing parentheses'()))'falsemissing opening parentheses')('falseclose before openThis problem is amenable to all sorts of s ...继续阅读 (24)

In this essay, we’re going to look at a game called Ayoayo. As we’ll read, Ayoayo is part of the Mancala family of games that has spread throughout Africa, and beyond. We’ll write some code that would be useful if we were implementing an Ayoayo game, and along the way, we’ll look at how we can keep our functions decoupled from each other and themselves with dependency injection.We’ll then look at how our gratuitous use of linear recursion also helps us keep our code decoupled, and teaches us how to write decoupled code even if we decided to use iteration.But first, some personal recollections. ...继续阅读 (41)

In this essay, we’re going to look at a game called Ayoayo. As we’ll read, Ayoayo is part of the Mancala family of games that has spread throughout Africa, and beyond. We’ll write some code that would be useful if we were implementing an Ayoayo game, and along the way, we’ll look at how we can keep our functions decoupled from each other and themselves with dependency injection.We’ll then look at how our gratuitous use of linear recursion also helps us keep our code decoupled, and teaches us how to write decoupled code even if we decided to use iteration.But first, some personal recollections. ...继续阅读 (31)

This is Part II of an essay that takes a highly informal look at two related techniques for achieving high performance when using large data structures:Structural Sharing, andCopy-on-Write Semantics.InPart I, we used recursive functions that operate on lists to explore how we could useStructural Sharingto write code that avoids making copies of objects while still retaining the semantics of code that makes copies.Here in Part II, we’ll considerresource ownership, starting with using copy-on-write semantics to implement safe mutation while still reserving structural sharing.a brief review of st ...继续阅读 (30)

This is Part II of an essay that takes a highly informal look at two related techniques for achieving high performance when using large data structures:Structural Sharing, andCopy-on-Write Semantics.InPart I, we used recursive functions that operate on lists to explore how we could useStructural Sharingto write code that avoids making copies of objects while still retaining the semantics of code that makes copies.Here in Part II, we’ll considerresource ownership, starting with using copy-on-write semantics to implement safe mutation while still reserving structural sharing.a brief review of st ...继续阅读 (24)

This essay takes a highly informal look at two related techniques for achieving high performance when using large data structures:Structural Sharing, andCopy-on-Write Semantics. In Part I, we’ll look at the background of Structural Sharing and start making aSliceclass that abstracts the concept of a slice of an array. InPart II, we’ll consider the problem of resource ownership when mutating objects.To give us some context for exploring these techniques, we’re going to solve a very simple problem:Programming in a Lisp-like recursive style, but using JavaScript arrays.Although not the most pract ...继续阅读 (39)

This essay takes a highly informal look at two related techniques for achieving high performance when using large data structures:Structural Sharing, andCopy-on-Write Semantics. In Part I, we’ll look at the background of Structural Sharing and start making aSliceclass that abstracts the concept of a slice of an array. InPart II, we’ll consider the problem of resource ownership when mutating objects.To give us some context for exploring these techniques, we’re going to solve a very simple problem:Programming in a Lisp-like recursive style, but using JavaScript arrays.Although not the most pract ...继续阅读 (20)

Alice and Bobbie were comparing notes after interviewing interns for an upcoming work term with their company, HipCo. Their interview process, although often maligned on social media, worked reasonably well for their purposes: They spent an hour with each candidate, devoting twenty minutes to introductions and some basic behavioural questions, about half an hour to a basic programming problem, and the remaining ten minutes or so was turned over to the candidate to ask them questions.They quickly went over all of the the candidates but one. Alice held that back for the end of their meeting.“And ...继续阅读 (24)

Alice and Bobbie were comparing notes after interviewing interns for an upcoming work term with their company, HipCo. Their interview process, although often maligned on social media, worked reasonably well for their purposes: They spent an hour with each candidate, devoting twenty minutes to introductions and some basic behavioural questions, about half an hour to a basic programming problem, and the remaining ten minutes or so was turned over to the candidate to ask them questions.They quickly went over all of the the candidates but one. Alice held that back for the end of their meeting.“And ...继续阅读 (15)

A popular programming “problem” is to determine whether a string of parentheses is “balanced:”Given a string that consists of open and closed parentheses, write a function that determines whether the parentheses in the string arebalanced. “Balanced” parentheses means that each opening symbol has a corresponding closing symbol and the pairs of parentheses are properly nested.For example:InputOutputComment'()'true'(())'trueparentheses can nest'()()'truemultiple pairs are acceptable'(()()())()'truemultiple pairs can nest'((()'falsemissing closing parentheses'()))'falsemissing opening parentheses ...继续阅读 (29)

A popular programming “problem” is to determine whether a string of parentheses is “balanced:”Given a string that consists of open and closed parentheses, write a function that determines whether the parentheses in the string arebalanced. “Balanced” parentheses means that each opening symbol has a corresponding closing symbol and the pairs of parentheses are properly nested.For example:InputOutputComment'()'true'(())'trueparentheses can nest'()()'truemultiple pairs are acceptable'(()()())()'truemultiple pairs can nest'((()'falsemissing closing parentheses'()))'falsemissing opening parentheses ...继续阅读 (26)

The Ruby programming language has the notion of aHash. AHashis a dictionary-like collection of unique keys and their values. Ruby hashes have most of the semantics of an ES6Map, but also have the syntactic conveniences of Plain-Old-JavaScript-Objects (“POJOs”).Interestingly, Ruby hashes also have the notion of programmatically determine a default value to be returned when accessing keys that have not been set. In JavaScript, the default value is alwaysundefined.In this essay we will look at rolling our ownHashclass with Ruby-like semantics, and then we’ll examine one of the most interesting th ...继续阅读 (39)