add a algebra simplification rules for range pattern match compiler

[bobzhang]

for example:

let rec fib = function
  | 1 | 2 | 5 | 33 -> 1
  | n -> fib (n - 1 )  + fib (n - 2)

function fib(n) {
  var exit = 0;
  var switcher = n - 1;
  if (switcher > 4 || switcher < 0) {
    if (switcher !== 32) {
      exit = 1;
    }
    else {
      return 1;
    }
  }
  else if (switcher === 3 || switcher === 2) {
    exit = 1;
  }
  else {
    return 1;
  }
  if (exit === 1) {
    return fib(n - 1) + fib(n - 2);
  }

}

this should be simplified

[justinba1010]

Gentle bump
The main issues we're running into involve the compilation of match statements such a,

let f x =
  match x with
  | x when (x > 3) && (x <= 11) -> 2
  | x when (x > 11) && (x <= 17) -> 5
  | x when (x > 17) && (x <= 23) -> 11
  | x when (x > 23) || (x < 145) -> 3
  | _x -> 7

This gets compiled to

function f(x) {
  if (x > 3 && x <= 11) {
    return 2;
  } else if (x > 11 && x <= 17) {
    return 5;
  } else if (x > 17 && x <= 23) {
    return 11;
  } else if (x > 23 || x < 145) {
    return 3;
  } else {
    return 7;
  }
}

We have a use case with hundreds of thousands of cases(unicode tables). We tried hash tables, and an array but we run into memory issues. And a standard match statement lead to long run times. Currently we use a b tree search to speed up our affected program.

[bobzhang]

this looks good to me, what’s your expected outcome? 发自我的iPhone

…

------------------ Original ------------------ From: Justin Baum <notifications@github.com> Date: Wed,Jul 24,2019 0:08 AM To: BuckleScript/bucklescript <bucklescript@noreply.github.com> Cc: Hongbo Zhang <bobzhang1988@gmail.com>, Author <author@noreply.github.com> Subject: Re: [BuckleScript/bucklescript] add a algebra simplification rules for range pattern match compiler (#59) Gentle bump The main issues we're running into involve the compilation of match statements such a, let f x = match x with | x when (x > 3) && (x <= 11) -> 2 | x when (x > 11) && (x <= 17) -> 5 | x when (x > 17) && (x <= 23) -> 11 | x when (x > 23) || (x < 145) -> 3 | _x -> 7 This gets compiled to function f(x) { if (x > 3 && x <= 11) { return 2; } else if (x > 11 && x <= 17) { return 5; } else if (x > 17 && x <= 23) { return 11; } else if (x > 23 || x < 145) { return 3; } else { return 7; } } We have a use case with hundreds of thousands of cases(unicode tables). We tried hash tables, and an array but we run into memory issues. And a standard match statement lead to long run times. Currently we use a b tree search to speed up our affected program. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub, or mute the thread.

[justinba1010]

We wanted a more functional run time for match statements. In some cases we were running in to extremely long times for large match statements that get run.

[stale]

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