Why do programming languages use curly braces?

http://programmers.stackexchange.com/q/188455/54164

by RKoutnik • 13 years ago

54 89 13 years ago

programmers.stackexchange.com

buster4• 13 years ago

I always wonder why so many languages are sooo bad to use on a non-us keyboard.. I'd love if language designers would consider other keyboard layouts more often.. :(

kd0amg• 13 years ago

FWIW, braces (and brackets and parentheses) aren't all that pleasant to type on a US keyboard either.

buster4• 13 years ago

This: https://en.wikipedia.org/wiki/File:KB_US-International.svg

is much easier then this: https://en.wikipedia.org/wiki/File:German-Keyboard-Layout-T2...

Of course that's probably the reason why the braces were chosen at all :P

ginko2• 13 years ago

There's dedicated keys for brackets and parentheses in relatively easy-to-reach positions. How could you make that more pleasant?

dlitvakb• 13 years ago

Most programmers often write their programs in english anyway, to be easy to share or to review by others (even in closed source software), so it makes sense for programming languages to mostly care about English keyboard layouts.

Anyways, if the keyboard layout is a blocking problem for you, consider changing it to what it suits you the best, or use multiple layouts for different tasks. Every operating system has a keystroke to swap layouts.

buster4• 13 years ago

It's not about writing english per se. How often do you need to write {[]}<> in a letter?

Those keys are really easy on US layout but horrible to type on a german keyboard layout. Holding alt-gr and press 7 or 8 or 9 or 0 is surely not impossible to type but compared to US layout it's much more worse, imo.

Fortunately Python does away with the overabundance of curly braces at least.

camus2• 13 years ago

it is one thing write programs in english , i have a french keyboard , typing english is fine , the problem is all the non word stuff that are not directly visible on my keyboard like {}[]|\] and so on. You kind of get used to it but frankly i dream of a language with non of these characters, just words. typing def/end doesnt bother me. By the way , that's kind of why i love coffee-script so much.

    myObject = 
       param1 : foo
       param2 : bar
       param3 : baz

    foo bar,baz,boom

my god it is a relief on a non english keyboard... on the mac i get the @attr without using alt-right , that is neat.

jonascopenhagen2• 13 years ago

I write software in English, sure, but my keyboard layout needs to be Danish in order for me to write emails, etc. in Danish. Having to swap keyboard layouts would mean I'd be confused constantly.

On a Danish Mac keyboard the curly braces are written by holding down Alt + Shift + 8. Not exactly an easy combination to hit.

> Most programmers often write their programs in english anyway

I'm not so sure about that. There are tons of places where English proficiency is really low, even among programmers.

rsaarelm• 13 years ago

I realized I probably write more curly braces than accented characters during the day and switched to using an US-International style keyboard layout that puts the diacritic characters under the Alt Gr key.

ygra5• 13 years ago

The APL [1] designers heard you and created a language impossible to type on almost every keyboard layout [2] ;-)

As for me, I've been using US International for a few years by now (because I use too many curly-braces languages and didn't want to give up being able to type ümläüts). But frankly, changing the keyboard layout just for a programming language is a bit evil. In that sense I liked BASIC and Pascal; I don't mind keywords instead of symbols that much either and I tend to be faster typing words anyway.

________

[1] http://en.wikipedia.org/wiki/APL_(programming_language)

[2] http://en.wikipedia.org/wiki/File:APL-keybd2.svg

itcmcgrath• 13 years ago

This made me search to see if there was any 256 key keyboards so I could have a key for every byte, but I apparently no one has been that crazy yet.

dexen• 13 years ago

In Poland, the most common layout is the `Polish (programmers)', virtually the same as US layout, with extra right Alt switching for polish accented characters.

The alternative is `Polish (typewriter)' layout, with accented characters replacing most of punctuation, which doesn't seem to have caught on. Apparently entering accented characters with right Alt is comfy enough.

Surprisingly all that happened in spite of MS Windows default settings -- IIRC up to and including Windows 98, MS Windows defaulted to the legacy `Polish (typewriter)' layout, and only since Win XP (or perhaps 7) it defaults to the common `Polish (programmers)'.

At any rate, have a look at http://www.colemak.com/ which is quite programmer-friendly. I am using a variation of it.

ginko2• 13 years ago

I'd rather say that keyboard layout designers should consider programming languages more often

cpeterso• 13 years ago

Or programming languages designers should consider keyboard layouts more often. :)

nzonbi2• 13 years ago

There is also the possibility of ditching entirely the approach of text based programming, for a more visual approach. This will not work for many people, but for those that it does work, it could improve productivity.

Text is a good way to represent sequences of information. So it fits programs well, to some extent. But programs contains various kinds of information, that doesn't fit well with a textual representation: Hierarchical data, scope, branching flow, loops, dependencies, etc. These can be enhanced by a visual representational that goes beyond just text.

Besides the Visual representation, there is also the UI. Things like Vim for example, can be awesomely productive, in the hands of someone that has mastered it. But I would claim, that there is still space for improvement. With a visual interface, there are lots of things that can be done. Touch interfaces have lots of possibilities. Special inputs devices, would also be a great opportunity. But that would be harder, for obvious reasons. Maybe 3D printing would open opportunities there soon. The key for a visual UI to succeed, is to allow to do more with less effort.

Visual programming has not succeed so far. I would argue that it is because it has not been done right yet. I am currently working on these ideas, with one of my weekend's side projects. Since my time is limited, It is still going to take some time.

kitsune_• 13 years ago

There are a lot of visual programming environments that are used in the creative industries, environments such as MAX/MSP, Pure Data, Houdini (CGI / FX) or NI Reaktor...

When I look at a complex Reaktor instrument (for instance Razor[1]), the entire paradigm seems to hit a wall at a certain point. The networks driving these instruments are an intricate mess and their visual representation can actually make it harder to grasp them in their entirety.

[1] http://www.native-instruments.com/en/products/komplete/synth...

kps4• 13 years ago

I'm not convinced it can be done right, because alphabets are inherently superior to ideograms. Making a small set of symbols capable of representing language is one of humanity's greatest inventions.

It's good to have an editor (like vi, following TECO) that takes advantage of the fact that this set of symbols is literally at the user's fingertips.

kps4• 13 years ago

Treat keyboard layouts as a part of your software tool set. If the one the OS gave you doesn't work well (and they are universally pretty bad), find or build one that does.

calinet6• 13 years ago

Well... why not?

--Edit: No, seriously, why not? There are only a few different opening-closing character pairs on a keyboard: [], (), <>, {}, /\, etc. It's not that different to type any of them.

So why is this even a question? It's because we used the others up and that was next on the list, and it looks somewhat logical as a container of things. So again, wholly and completely, the answer is in the question: "why not?"

jonascopenhagen2• 13 years ago

Because on non-English keyboards curly braces are a pain to type. E.g. in Danish it requires Alt + Shift + 8 (on a Mac), and if you look at the comments above you'll see that the problem is the same for many other languages.

cgrubb• 13 years ago

Features of BCPL (Martin Richards, 1967):

  * used { } instead of BEGIN and END keywords
  * single type called WORD
  * declared variables with LET
  * used // style comments like C++

Features of B (Ken Thompson, 1969):

  * used = instead of := for assignment
  * variables could be declared AUTO or STATIC
  * semicolons as statement terminators
  * ++ and -- incrementors/decrementors in prefix and postfix position

Features of early C (Dennis Ritchie, 1970)

  * two types: int and char
  * struct introduced in 1973
  * /* */ style comments from PL/I
  * && and || operators with short-cut semantics

pjmlp4• 13 years ago

Sadly proper arrays and strings were left somehow along the way.

kps4• 13 years ago

BCPL vectors seem to be the same as C arrays, no?

dmr wrote at http://cm.bell-labs.com/cm/cs/who/dmr/bcpl.html that “C was invented in part to provide a plausible way of dealing with characters when one begins with a word-oriented language. [...] BCPL later found a solution better, on its own terms, by providing an operator (%) analogous to its !, such that v%i designates the i-th character in a vector. However, the earliest BCPL applications tended not to process packed characters in vectors, but to spread them out early into one character per word, process, and then pack them again if necessary.”

dangoldin• 13 years ago

A meta comment: It's pretty awesome that we're already having lore discussions about our craft 50 years later. I wonder what they'll be discussing in a 100 years about our languages now and why certain decisions were made.

pjmlp4• 13 years ago

We will discussing how it was possible that C could endure for so many years delaying the use of safer languages for systems programming along the line of Modula-2 and Ada.

alan_cx• 13 years ago

Modula-2 ????????

Is that serious language then? We learned that back at University when I was doing my CS degree. Other students were scathing about it, going on about why we weren't doing C. But it was used as a simple introduction to programming techniques to prepare for C, Java etc. I understood its value back then as an introduction, but I never realise it had a use beyond that. I have to say, I quite enjoyed using it, and I was a little disappointed to move way from it to "proper" languages at the time.

So, it is used in anger, as it were, now? If so, what can it be used for? Part of me would love to pick it up again for something vaguely serious.

k3n3• 13 years ago

Tokens of a bygone era.

I wish more languages were like Python and didn't require so many cruft characters.

cobrausn2• 13 years ago

The first time I ran into the spaces vs. tab problem I wanted my curly braces back.

rejschaap• 13 years ago

Invisible cruft! The worst.

Also, Python is crufty by convention with its __init__ and __new__.

k3n3• 13 years ago

That's an issue you run into once, set your editor, and then never have to worry about it again.

On the other hand, curly braces will plague you as long as you use C-inspired languages. An editor will only help you to more easily produce the cruft, it won't absolve you of the responsibility.

manaskarekar2• 13 years ago

Or lisps. Commas in sequences? Cruft!

jgrahamc• 13 years ago

and why not something more reasonable, like [], which doesn't require the shift key at least on US keyboards

The OP is assuming the current US keyboard layout. C was developed on the PDP-11 which would likely have used a DECwriter II for the keyboard/output.

On that keyboard [ ] are on the same key (non-shift is [, shift is ]). Thus [ ] were not 'easier' on it. Similarly, { } were on the same key with non-shift being { and shift being }.

C's predecessor BCPL used { } although it was developed on a machine without a keyboard and so typing those characters was just as easy as any other character. The developer might have had access to an IBM card punch with a keyboard but the keyboards on those were odd (IBM layout) with no [] or {} and $( was used in place of {.

limmeau• 13 years ago

On German (and I think also Dutch) keyboards, {} are on AltGr-7 and 0, which is a pain to type (and the reason why I switch every computer to US keyboard). I wonder if that's why Python uses indentation and not braces for blocks...

Tripfag2• 13 years ago

Flemish (Belgian Dutch) keyboards have them at AltGr9 and AltGr0. Works just fine, if you ask me.

sjmulder• 13 years ago

Dutch people use US International layout keyboards almost exclusively (@ above 2). The Dutch layout (# above 2) is very very rare.

Turing_Machine2• 13 years ago

"$( was used in place of {."

That was very common. The C compilers for the Atari 8 bit computers (which used the ASCII values for { and } for graphics characters) did this too.

mirkules• 13 years ago

My preference on an American keyboard is still curly braces, probably because of my typing style.

In order to type { }, I hit the shift key with my right pinkie finger, which shifts my entire hand over and allows me to hit the brackets with precision with my middle or ring finger. When I type [ ], I use my middle and ring fingers but without anchoring my hand to the right shift key, and I often hit the wrong character.

This is why I always found it awkward to program in Objective-C due to their extensive use of square brackets, whereas Java or PHP (or other C-like languages) come a lot more naturally (curly braces are more often used than square ones).

groovy2shoes• 13 years ago

As far as I can tell, after having read Martin Richards's BCPL book and the BCPL reference manual, BCPL allowed only $( $) as section brackets. Looking at the current BCPL compiler code, it seems that it does now allow { } for section brackets, but the comments in the compiler suggest that it wasn't added until 1995. BCPL's section brackets were neat in that you could add a label to them and they would be parsed much like HTML tags. I think it's likely that B introduced the curly brackets in lieu of BCPL-style section brackets and omitted tagged brackets altogether, then B begat C, etc.

dragonwriter• 13 years ago

> and why not something more reasonable, like [], which doesn't require the shift key at least on US keyboards

[] are used for indexing, which is probably used more. So regardless of the historical reason, it makes sense to use something visually distinct for blocks.

pmelendez• 13 years ago

[Slightly off topic] It's just me or now a lot of very interesting threads in SO are being closed as "not constructive"

Should we start to looking for a place to start this kind of discussion without lose the Q&A format? Reddit and HN might work but just a few of 'Ask HN' posts actually make the front page and, in my opinion, answers on Reddit don't have the same quality in comparison with SO.

manaskarekar2• 13 years ago

Simple answer: http://meta.stackoverflow.com/questions/110350/why-are-usefu...

Not a fan of this myself. When there is a pool of thousands of smart people who are willing to answer in a certain format, hundreds of thousands who are looking to read those answers in that format, outright banning that format is a little unfortunate in my opinion.

If you want to maintain a certain style for SO, then perhaps there's some outlet for these "discussion format" style questions on there that could be marked as such.

To disallow smart people from solving problems because they don't adhere to one strict format is a tragedy.

jiayo• 13 years ago

They already split off "programmers" from the main StackOverflow site to address this exact issue, and history is repeating itself. Now it seems we need individual sites for programmers-offtopic, programmers-trivia, programmers-history. Make those, and as time goes by, each one will be moderated more and more heavily until they form their own spinoffs.

lelandbatey• 13 years ago

This is very much a side comment, but I've noticed that there are a lot of these kinds of questions on StackExchange, but it seems like a lot of them are closed (this one was closed within an hour of it being opened) because they don't fit within the goals of StackExchange.

My question is: is there somewhere else where these kinds of questions (not totally on topic but still relevant to what programmers do) can be asked? I'd love to see more of them!

thoughtpalette• 13 years ago

http://programmers.stackexchange.com/

"This is a collaboratively edited question and answer site for professional programmers interested in conceptual questions about software development."

smackfu• 13 years ago

You would think, but the same question was closed there as Not Constructive:

http://programmers.stackexchange.com/questions/188455/why-do...

Very common on StackExcahnge. A bunch of high rep users swoop in and close questions that don't meet this weeks version of the rules that were decided in the Meta site that only the high rep users read. It reminds me a lot of Wikipedia.

sharkweek• 13 years ago

I really like the /r/learnprogramming subreddit -- You can ask anything relevant to programming and you'll get earnest answers with minimal trolling (the mods do a great job there).

insteadof• 13 years ago

You'll have to create an audience draw for it as well. Say, promise them the site won't be overrun by endless discussions about which Aeron chair is the best to sit on a treadmill.

Then when you have the audience who were drawn in by the high signal focus on a topic of expertise, sucker punch them by closing down all such questions and cite some lame excuse of following the charter of purity. In the name of site quality they'll say.

eli_gottlieb• 13 years ago

Yes, there is a place. Usenet is a popular forum for holy wars about the lexical syntax of various programming languages.

DodgyEggplant• 13 years ago

The "what question is interesting enough to reach HN front page so we can close it" watch is alert and active, thank you

Thrall• 13 years ago

I sometimes wonder why languages use sequences like "->". This is clearly meant to represent an arrow, so why has noone ever taken the time to make sure an arrow character is defined, make sure it's possible to type it in most keyboard maps and use it in programming languages.

It can't be because physical keyboards wouldn't have the key, because my keyboard doesn't display a # symbol, but that is widely used.

I can only guess that the character sets and "what characters are easy to type into a computer" became standardised early on, and no individual language has been able to push such a change (Early in development a language has few users, thus no influence; Later in development, the language has been using "->" itself for a while, so it's less easy to change).

Also, proper languages like lisp use parentheses (), not curly braces. :p

AlexanderDhoore2• 13 years ago

Not entirely the same thing, but there are some plugins for Vim, Emacs,... that show different figures/characters in place of things like "=>" or "lambda". But don't actually change your source code.

For example: https://github.com/ehamberg/vim-cute-python

spacemanaki• 13 years ago

Some languages do support Unicode for things like arrows and other mathematical symbols: http://wiki.portal.chalmers.se/agda/pmwiki.php?n=ReferenceMa...

Languages which support this (including Agda, I believe) usually support some fallback to ASCII, allowing you to type "->" instead of a Unicode arrow, because it's easier to type on the vast majority of keyboards.

Of course, APL also famously uses all kinds of symbolic nonsense.

kps4• 13 years ago

Several early programming systems did use custom character sets (custom type bars) as well as typewriter-oriented notations like overstrikes, half-line motions for superscripts (powers) and subscripts (indexes), and colour (red half of the ribbon for comments)¹. Except for APL, which had IBM behind it, these tended not to escape their original research environments.

Relatively large-scale production required I/O devices to share a common character set. These tended to be based on pre-computer character sets (teletypes, punched cards) and were limited in size both by the I/O devices and by storage requirements (don't forget how small and expensive memories were). A lot of work went into choosing character sets.²³⁴

1963 ASCII had an up arrow ‘↑’ dropped in 1967 in favour of ^ (because furriners wanted accents), and a left arrow ‘←’ dropped in favour of ‘_’.⁵⁶

¹Jean Sammet, Programming Languages: History and Fundamentals 978-0137299881  ²Charles E. MacKenzie, Coded Character Sets: History and Development 978-0201144604  ³http://www.trailing-edge.com/~bobbemer/SURVEY.HTM ⁴R W Bemer, Design of an improved transmission/data processing code http://dx.doi.org/10.1145/366532.366538  ⁵American Standard Code for Information Interchange http://www.wps.com/projects/codes/X3.4-1963/index.html  ⁶Revised U.S.A. Standard Code for Information Interchange http://www.wps.com/J/codes/Revised-ASCII/index.html 

abecedarius• 13 years ago

Smalltalk uses [] for blocks, and somehow it just looks jagged and unpleasant to read, to me: [[[]]] doesn't nest nicely like ((())) or {{{}}}. I don't propose this as an explanation of anything; but I'm glad it isn't [].

restlessmedia• 13 years ago

I wonder what percentage of questions with the highest hit rate on SO and SE have "closed as not constructive by x" on them.

My 3 groats here says lots.

Why do programming languages use curly braces?

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