nim-lang/Nim

Nim is a compiled, garbage-collected systems programming language which has an excellent productivity/performance ratio. Nim's design focuses on efficiency, expressiveness, elegance (in the order of priority).

Kaushal Modi

@kaushalmodi

@mratsim yep :)

but that jumbled order still bugs me

Mamy Ratsimbazafy

@mratsim

uh no, you need to define the proc then call it

Kaushal Modi

@kaushalmodi

it's like you define a proc with the types and input value, but then you pass the proc definition when you actually call it

Miran

@narimiran

why jumbled? you can use this example now not only for plusOne, but for any other int -> int function

Mamy Ratsimbazafy

@mratsim

fn is not the actual proc though, it’s a stub

it’s instantiated at call site

Kaushal Modi

@kaushalmodi

@mratsim hmm.. "but for any other int -> int function" makes sense

Mamy Ratsimbazafy

@mratsim

define the higher order function —> define it’s body —> call it with a function as parameter

Kaushal Modi

@kaushalmodi

thanks

Miran

@narimiran

maybe it would be clearer if you didn't call it plus1, but use2

Kaushal Modi

@kaushalmodi

@narimiran yeah.. I was translating directly from that elisp snippet

but..

still the input arg gets hardcoded in that use2 wrapper

Mamy Ratsimbazafy

@mratsim

@kaushalmodi

import sugar
proc plus1(fn: int -> int, x: int): int = # 1. define the proc param and return types
  fn(x)
echo plus1(x => x + 1, 2)


import sugar
proc plus1(x: int): int = # 1. define the proc param and return types
  x + 1
echo plus1(2)

Kaushal Modi

@kaushalmodi

ok.. this is better:

import sugar
proc int2int(fn: proc(x: int): int, inp: int): int = # 1. define the proc param and return types
  fn(inp) # 3. call the proc with the actual args
echo int2int(x => x + 1, 2) # 2. define what the fn in plus1 should do

hehe

Miran

@narimiran

yes, that is better :)

From IRC (bridge bot)

@FromIRC

<Yardanico> @Araq are there any examples on how to use --gc:regions? Because person in Telegram tells that he just added --gc:regions and he can use GCd code on esp8266

From IRC (bridge bot)

@FromIRC

<endes[m]> https://gitlab.com/NetaLabTek/Arduimesp

Ray Imber

@rayman22201

Damn that is cool!

Kaushal Modi

@kaushalmodi

@mratsim @narimiran Building up that example to one more complication level..

import sugar
proc twoInts2Int[T](fn: (int, int) -> int; x, y: T): T =
  ## Wrapper proc to define the ``fn`` type, and to pass its inputs.
  fn(x, y)
echo twoInts2Int((x, y) => x + y, 2, 3)

Is there a way to not hard-code the fn type to deal with ints?

Miran

@narimiran

proc twoInts2Int[T](x, y: T, fn: (T, T) -> T): T =
  ## Wrapper proc to define the ``fn`` type, and to pass its inputs.
  fn(x, y)
echo twoInts2Int(2.0, 3.5, (x, y) => x + y)

notice the change in the order of parameters

Kaushal Modi

@kaushalmodi

yeah.. was going to ask that

I had the opposite order.. didn't work

@narimiran :+1: Works! Thanks.

Miran

@narimiran

i think the type is inferred from the first parameter, so it has to be something with the known type - anonymous function isn't

Kaushal Modi

@kaushalmodi

Here's the result of all that Q&A: https://scripter.co/notes/nim/#lambda. Thanks @narimiran and @mratsim for your help!

Varriount

@Varriount

dom96: Where did you here that?

(Regarding Python and :=)

Miran

@narimiran

thanks for the mention @kaushalmodi! it's these small things that make me happy :)

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@FromIRC

<dom96> https://news.ycombinator.com/item?id=17448439

<Yardanico> @kaushalmodi but don't forget that you don't need => for lambda

<Yardanico> oh I see

Kaushal Modi

@kaushalmodi

Yardanico:.. yes :)

the last line

From IRC (bridge bot)

@FromIRC

<Yardanico> anonymous procedures = lambdas, right?

Kaushal Modi

@kaushalmodi

yes

I just chose to hyperlink the => with #lambda and the other with #anonymous-procedures as the latter is the "official name" from Nim Manual

From IRC (bridge bot)

@FromIRC

<dom96> makes sense :⁠)

Miran

@narimiran

@kaushalmodi the example after the line "Here are few more examples of using => and ->:" won't work for some general type T

because of the signature of anonymous proc

Kaushal Modi

@kaushalmodi

@narimiran You are right.. they are remnants of me trying to make generics work..

I will remove generics from those two int, flt examples

thanks

Miran

@narimiran

no problem :)

btw, if you'll extend your list comprehension part - try to compare the syntax with map(It) for the same examples, to see what is clearer/nicer to you

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