Araq

Cheap exceptions

Goals:

• Avoid Rust's Option/Either manual error handling strategy.
• Make exceptions cheaper.
• Avoid error translation between Nim libraries by construction. The new vocabulary type ErrorCode is what should be used. Wrappers should translate errors to ErrorCode.
• Make the error out of memory easier to handle.
• Resolve once and for all the "error codes vs exceptions" choice.

Araq

Pointer free programming

What do ParaSail, "modern" C++ and Rust have in common? They focus on "pointer free programming" (ok, maybe Rust doesn't, but it uses similar mechanisms). In this blog post I am exploring how we can move Nim into this direction. My goals are:

Araq

This document describes how Lambda Lifting (LL) works. LL is responsible for transforming 'closures' into (environment, function) pairs.

The basic approach is that captured vars need to be put on the heap and that the calling chain needs to be explicitly modelled. Things to consider:

proc a =
  var v = 0

Araq

include prelude

type
  Node {.acyclic.} = ref object
    le, ri: owned Node

proc checkTree(n: Node): int =
  if n.le == nil: 1
  else: 1 + checkTree(n.le) + checkTree(n.ri)

Araq

import macros

proc generateAccessors(name, hidden, typ, fieldTyp: NimNode): NimNode =
  template helper(name, hidden, typ, fieldTyp) {.dirty.} =
    proc name*(self: typ): auto = self.hidden
    proc `name=`*(self: var typ; val: fieldTyp) =
      self.hidden = val
  result = getAst(helper(name, hidden, typ, fieldTyp))

proc transform(n: NimNode; stmts, obj: NimNode): NimNode =

Araq

discard """
  cmd: "nim c --gc:orc $file"
  output: '''
{"age": 12, "bio": "Я Cletus", "blob": [65, 66, 67, 128], "name": "Cletus"}
true
true
alpha 100
omega 200
0'''
"""

Araq

import asynchttpserver, asyncdispatch, strutils, json, tables, streams

# about 130 MB of alive data:
var sessions: Table[string, JsonNode]

for i in 0..<10:
  sessions[$i] = parseJson(newFileStream("1.json", fmRead), "1.json")

var served = 0

Araq

import macros

macro awaitE(call: typed, r: untyped): untyped =
  let x = call[0]

  let tx = x.getType()
  expectKind tx, nnkBracketExpr
  var t = newTree(nnkProcTy)
  var p = newTree(nnkFormalParams, tx[1])

Araq

import strutils, os

type Target = tuple[repo, package, ext: string]

proc newTarget*(path: string): Target =
  let splat = path.splitFile
  result = (repo: splat.dir, package: splat.name, ext: splat.ext)

let mem = getOccupiedMem()

Araq

const
  intrin = "<x86intrin.h>"
{.localPassC: "-msse4.2".}
type
  M128i {.importc: "__m128i", header: intrin, bycopy.} = object

const
  SIDD_CMP_RANGES = 0b0000_0100'i32
  SIDD_NEGATIVE_POLARITY = 0b0001_0000'i32