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Microfeatures I'd like to see in more languages

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Re: Microfeatures I'd like to see in more languages

#41

Post by amalgamated_inc »

wging wrote: post #28
pgorczak wrote: post #12

Clojure’s loop expression hits this spot for me. It sets a recursion point to which you can jump using any logic inside the body you want, as long as it is from tail position. It’s like a while loop turned into an expression. I haven’t encountered any other way to write iterative expressions whose number of iterations isn’t known at the top (like map and reduce).

Tail call optimization can get you that, too. If you've written Scheme and/or gone through SICP you might be familiar with this: you write a recursive function, with the recursive function call as the last thing the function does ('tail-recursion'), and the compiler/runtime is able to optimize those recursive calls out rather than consuming one stack frame of space per call ('tail call optimization'). Clojure has loo…

Interestingly, I almost prefer Clojure's `recur` semantically. Means you don't have to change the function name twice if you rename it, and it's hard to miss that you're recursing.

Re: Microfeatures I'd like to see in more languages

#42

Post by tremon »

xigoi wrote: post #4

My favorite is uniform function call syntax. In several languages (Nim, Koka, D, …), you can always write bar.foo(baz) instead of foo(bar, baz) and vice-versa. Another one from Nim is the implicit result variable. Instead of having to do this: func sum(nums: seq[int]): int = var result = 0 for num in nums: result += num return result you just do this: func sum(nums: seq[int]): int = for num in nums: result += num It…

and vice-versa

Doesn't the reverse pollute the function namespace? If every obj.fun() can be written as fun(obj), doesn't that cause ambiguity with a previously imported global function fun()?

Re: Microfeatures I'd like to see in more languages

#43

Post by mr_mitm »

japanman425 wrote: post #19
mr_mitm wrote: post #17

I really liked the postfix and prefix notation in Mathematica. These three all mean the same: f[x] f@x x // f It matches the flow of thought more naturally when hammering out a couple of one-liners.

How is that third one readable at all? I’d assume it meant integer division.

That's just a matter of habit. The exact symbol isn't important anyway.

Re: Microfeatures I'd like to see in more languages

#44

Post by masklinn »

progval wrote: post #29
revskill wrote: post #8

Earlier quoted context omitted.

Is it for performant reason ?

Symbols can even improve performance. Replace them with integers at compile time like a global enum, and so the runtime only needs to compare integers instead of potentially lengthy (especially if UTF-16) strings.

> Replace them with integers at compile time like a global enum, and so the runtime only needs to compare integers instead of potentially lengthy (especially if UTF-16) strings.

All of those strings will be interned, and can thus be compared by identity. Which is an integer comparison.

Re: Microfeatures I'd like to see in more languages

#45

Post by amalgamated_inc »

Elixir's sigils are amazing. There are date sigils that allow you to do what the OP does: ~N[2023-01-01 12:00:00]

But you can also define your own sigils to create new "custom syntax" for almost any struct. Kind of a special case of reader macros, I guess. Very convenient.

Re: Microfeatures I'd like to see in more languages

#46

Post by iwsk »

davidhyde wrote: post #31

> You can write # 2001-08-12 # to mean the date 2001-08-12, instead of writing something annoying like Date(2001, 8, 12) I like this article but oh man dates just trigger me. Such a missed opportunity to use an unambiguous date example like 2001-08-13

It would have been unambiguous in a world where we all agreed that both months and days start at 0 :)

Re: Microfeatures I'd like to see in more languages

#49

Post by tremon »

japanman425 wrote: post #20
pgorczak wrote: post #12

Clojure’s loop expression hits this spot for me. It sets a recursion point to which you can jump using any logic inside the body you want, as long as it is from tail position. It’s like a while loop turned into an expression. I haven’t encountered any other way to write iterative expressions whose number of iterations isn’t known at the top (like map and reduce).

for x in y: yield x Job done

Also known as (in Python, that is):

  yield from y

Re: Microfeatures I'd like to see in more languages

#50

Post by RodgerTheGreat »

happyrock wrote: post #3

I have long wondered why Ruby's symbols aren't in every language.

They exist in K/Q. A single-word identifier-shaped symbol begins with a backtick, or a multi-word symbol can be created with a backtick and double quotes. A sequence of symbols is a vector literal, and is stored compactly. For example:

    `apple
    `"cherry pie"
    `one`two`three
Many languages will intern string literals implicitly, or allow a programmer to explicitly intern a string; for example Java's "String.intern()".

The problem with string interning, especially for strings constructed at runtime, is that for the interning pool to be efficient it is very desirable for it to be append-only, and non-relocatable. A long-running program which generates new interned strings on the fly risks exhausting this pool or system memory.

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