Per-iteration variable in Nim?

Question

var functions: seq[proc(): int] = @[]
functions.add(proc(): int = 233)
for i in 1 .. 5:
  functions.add(proc(): int = i)

for i in 1 .. 5:
  echo functions[i]()

output

5
5
5
5
5

Seems like Nim stores free variable i in these anonymous functions by reference instead of values just like Python, Ruby and Groovy. How can I get its value instead of reference?

Answer 1

You can use the capture macro, see the docs in std/sugar

import std/sugar
var functions: seq[proc(): int] = @[]
for i in 1 .. 5:
  capture i:
    functions.add(proc(): int = i)

for fn in functions:
  echo fn()

There's also captureScope in system (system module is always implicitly imported), but the docs suggest using capture from std/sugar.