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

hmm

btw just replace fmt to & did not make any difference, still fails

next, will use the let trick you suggested

Mamy Ratsimbazafy

@mratsim

@jrfondren there was too many unintentional errors with unary <10

now you should use ..< without space and unary < (previous) will be removed

From IRC (bridge bot)

@FromIRC

<nc-x> Araq: I will open an issue in a few minutes once I get a minimize the code

Kaushal Modi

@kaushalmodi

Araq: OK, that let trick worked: http://ix.io/1GrY

Ghost

@ghost~5b68e3cbd73408ce4fa3b6b0

I remembered that. I just wondered how I'm expected to learn that.

Mamy Ratsimbazafy

@mratsim

so 0 ..< 10 remains but 0 .. <10 is warned about

Kaushal Modi

@kaushalmodi

Araq: what's a simple explanation for that behavior? (so that I can put in my notes)

also, do you think that will be fixed?

Mamy Ratsimbazafy

@mratsim

the new deprecation indicates what is the replacement

deprecations*

you can do a PR to add that to <

From IRC (bridge bot)

@FromIRC

<Araq> @kaushalmodi: fields/fieldPairs is very special in the compiler, we have to unroll the loop in the frontend and we likely got it wrong :⁠P

Kaushal Modi

@kaushalmodi

looks like I hit the nail on the head with that issue title

I played with numerous fmts in for loops and got confused what was special about looping through objects :P

Mamy Ratsimbazafy

@mratsim

it's not a loop

Kaushal Modi

@kaushalmodi

i mean iterating through values yielded by fields/fieldPairs

Mamy Ratsimbazafy

@mratsim

yeah, I mean what's special is that it's not a loop :p

Kaushal Modi

@kaushalmodi

sorry, I am confused

you mean that the for behaves differently for fields/fieldPairs?

Ghost

@ghost~5b68e3cbd73408ce4fa3b6b0

the fields are statically known so the loop is fully unrolled, yeah?

Kaushal Modi

@kaushalmodi

so what is different that fields/fieldPairs doesn't work, while this works?:

import strformat
for i in @[1, 2, 3]:
  echo fmt"{i}"

Mamy Ratsimbazafy

@mratsim

in that case it's a real loop in the generated code

in the other case, Nim inserts as many "echo" as the number of fields in your objects

Kaushal Modi

@kaushalmodi

huh, really? TIL

Mamy Ratsimbazafy

@mratsim

And I'm pretty sure that the compiler then chokes on semantic type checking the formats

Kaushal Modi

@kaushalmodi

so that whole for key,val in foo.fieldPairs is a special construct?

Mamy Ratsimbazafy

@mratsim

yes

key/val only exists at compile time and the types is a weird compile-time polymorphic stuff

Kaushal Modi

@kaushalmodi

ok .. not sure how to note that down :P But for now I'll use fields/fieldPairs with caution

Mamy Ratsimbazafy

@mratsim

well it doesn't really cause problems in my experience, just hard to decipher error messages

also that means that if you want to test a condition on the keys, you need to use when to avoid type errors

like "when key is string:"

Kaushal Modi

@kaushalmodi

Thanks for all that info

From IRC (bridge bot)

@FromIRC

<narimiran> @kaushalmodi: see this also nim-lang/Nim#7533

<narimiran> "Warning: This really transforms the 'for' and unrolls the loop. The current implementation also has a bug that affects symbol binding in the loop body."

Mamy Ratsimbazafy

@mratsim

wow the error message is even worse that what I met so far

Kaushal Modi

@kaushalmodi

man, timotheecour is really missed here

narimiran, Araq: you guys should finally strike up some truce with him

From IRC (bridge bot)

@FromIRC

<livcd> oh noes fmt goes away?

Kaushal Modi

@kaushalmodi

narimiran: probably related to that system sub-module separation? cannot find fieldPairs in https://nim-lang.github.io/Nim/theindex.html

looks that most of what I am looking for in system is missing from the devel docs

From IRC (bridge bot)

@FromIRC

<narimiran> yes, probably. look at iterators.nim:205 (and you'll see it is just a magic :⁠))

Kaushal Modi

@kaushalmodi

yes, I see that in stable docs: https://nim-lang.org/docs/system.html#fieldPairs.i%2CS%2CT

From IRC (bridge bot)

@FromIRC

<nc-x> Araq: nim-lang/Nim#11050

Kaushal Modi

@kaushalmodi

I had stopped using the stable docs for a while now .. can fixing the devel docs be bumped up in priority?

From IRC (bridge bot)

@FromIRC

<Araq> @nc-x, 'method'?

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