Examples: Fix compiling issues and imports, closes #69

[dlesnoff]

Fix compilation errors for many examples.
Change import bigints to import ../src/bigints to ensure examples are tested with the development version and not the stable version. This might be changed back when a stable version is going to be released.
Changed imports from standard library to differentiate them from external libraries :
import strutils, math become import std/[strutils, math]
As there is no implicit type conversion for integers to BigInt anymore, operations between a BigInt and an Integer now become operations between BigInt and integer explicitly converted to BigInt.
Now three examples do not work :

• pidigits.nim - rangeDefect
• rc_pidigits.nim - rangeDefect (almost identical to pidigits.nim)
• rc_godtheinteger.nim - infinite Loop (takes more than 30 seconds)
• rc_leftfactorials.nim - depends on an external library iterutils.
• rc_paraffins.nim

[pietroppeter]

#69 (comment)

[dlesnoff]

Sorry I have seen your comment after my PR, I am going to rebase my fix.

[pietroppeter]

rc_godtheinteger.nim - infinite Loop (takes more than 30 seconds)

see http://rosettacode.org/wiki/9_billion_names_of_God_the_integer#Nim that version is supposed to be slow and as such should not be kept running. version 2 is the fast one.

[dlesnoff]

I have :

• changed imports back to import bigint
• added a nim.cfg
• in src/bigints.nim, there is now a ^ decorator for pow. Why was this removed ?
  It helps to keep some examples easy to read in my opinion.
• I can not compile anymore rc_parafins.nim. It fails at line 42. I am unsure yet how to fix it.
• rc_pidigits.nim and pidigits.nim are still broken, it would take me a lot of time to understand the algorithms and rewrite them.
• @def- Is it possible to replace the slice iterator from iterutils package in your example, to remove iterutils dependency ?

[narimiran]

@konsumlamm, your review please :)

[pietroppeter]

Is it possible to replace the slice iterator from iterutils package in your example, to remove iterutils dependency ?

I would adapt rc_leftfactorials.nim it to something like this (playground):

iterator square: int =
  var i = 0
  while true:
    yield i*i
    inc i

var i = 0
for n in square():
  if i <= 10:
    echo i, ": ", n
  elif i <= 110 and i mod 10 == 0:
    echo i, ": ", n
  elif i >= 1000 and i <= 10_000 and i mod 1000 == 0:
    echo i, ": ", n
  elif i > 10_000:
    break
  inc i

[pietroppeter]

in examples/rc_godtheinteger.nim you could change this line:

for x in [23, 123, 1234, 12345]:

to

# for 12345 this implementation is too slow, for a faster implementation see rc_godtheinteger2.nim
for x in [23, 123, 1234]:

[dlesnoff]

Thanks a lot @pietroppeter, the two new commits follow up from your ideas.

[dlesnoff]

This example can not be rewritten as long as we have not defined a way to convert a BigInt into an int, see issue #72. Type cast does not do the same thing, it interprets the BigInt as an int ! So the first limb is understood as the 2’s complement representation of another number. Thanks @konsumlamm for the explanation. Same for examples/rc_pidigits.nim

[konsumlamm]

In the future, we should also test these examples in the CI (I didn't even know they existed until recently).

[dlesnoff]

All examples compile, only pidigits examples does not work but this may be fixed with PR #74.

[dlesnoff]

Pidigits examples now compile, but in case toSignedInt change name, we will have to modify slightly the examples again.
In pidigits.nim, I added command line basic parsing. I thought it was broken, because I did not provide an argument, and nothing explained that an argument was expected.

[dlesnoff]

@konsumlamm or @pietroppeter may I ask for a review on this PR ?

[konsumlamm]

Can you change the link in examples/rc_godtheinteger.nim to https://rosettacode.org/wiki/9_billion_names_of_God_the_integer and change all links to https?

[konsumlamm]

This link is broken.

[konsumlamm]

Also, isn't this example essentially a duplicate of rc_pidigits.nim?

[dlesnoff]

The pidigits.nim file is the interactive version of rc_pidigits.nim
The pidigits.nim asks the user for the number of digits of pi he wants, whereas rc_pidigits.nim prints indefinitely new digits of pi.
I can remove rc_pidigits.nim if you want. Especially knowing that the code (now outdated) is published on the website.

[konsumlamm]

I don't really care which one we keep.

[dlesnoff]

@narimiran May I ask to merge this PR ?