Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.3.9)
// Compass (v1.0.0.alpha.20)
// ----

// Tests whether all items from `$list` pass the test implemented by `$function`.
//
// @param {List}    $list     - list to run test against
// @param {String}  $function - function to run against every item from list
// @param {ArgList} $args     - extra arguments to pass to the function
//
// @return {Bool}

@function every($list, $function, $args...) {
  @each $item in $list {
    @if not call($function, $item, $args...) {
      @return false;
    } 
  }
  
  @return true;
}

// Tests whether some items from `$list` pass the test implemented by `$function`.
//
// @param {List}    $list     - list to run test against
// @param {String}  $function - function to run against every item from list
// @param {ArgList} $args     - extra arguments to pass to the function
//
// @return {Bool}

@function some($list, $function, $args...) {
  @each $item in $list {
    @if call($function, $item, $args...) {
      @return true;
    } 
  }
  
  @return false;
}

// Dummy tests
// See below for a real test

$test_1: some, every;
$test_2: some, every, whatever;
$test_3: whatever, string;
$test_4: 1em, 2%, 3px;
$test_5: 1em, 2, 3px;
$test_6: 1, 2, 3;

every {
  test_1: every($test_1, function-exists);
  test_2: every($test_2, function-exists);
  test_3: every($test_3, function-exists);
  test_4: every($test_4, unitless);
  test_5: every($test_5, unitless);
  test_6: every($test_6, unitless);
}

some {
  test_1: some($test_1, function-exists);
  test_2: some($test_2, function-exists);
  test_3: some($test_3, function-exists);
  test_4: some($test_4, unitless);
  test_5: some($test_5, unitless);
  test_6: some($test_6, unitless);
}

// Practical use case
// Sum all values from list

@function is-number($value) {
  @return type-of($value) == "number";
}

@function sum($list) {
  @if not every($list, is-number) {
    @warn "All values from list have to be numbers for `sum`.";
    @return false;
  }
  
  $result: 0;
  
  @each $item in $list {
    $result: $result + $item;
  }
  
  @return $result;
}

test {
  sum: sum(1 2 3 4);
  sum: sum(1 2 3 string);
}

SassMeister-output.css

every {
  test_1: true;
  test_2: false;
  test_3: false;
  test_4: false;
  test_5: false;
  test_6: true;
}

some {
  test_1: true;
  test_2: true;
  test_3: false;
  test_4: false;
  test_5: true;
  test_6: true;
}

test {
  sum: 10;
  sum: false;
}