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"Pyret has numbers, because we believe an 8GB machine should not limit students to using just 32 bits." Java Pyret // this is not true

"Pyret has numbers, because we believe an 8GB machine should not limit students to using just 32 bits." Java Pyret // this is not true # this is true ((1 / 3) * 3) == 1 ((1 / 3) * 3) == 1 wat How about ((1.0 / 3) * 3) == 1? Not sure what point they are trying to make here. Did somebody change the definition of "number" to mean "floating point type?"

JonathonW 12y ago
From what I'm reading, Pyret numbers are either exact rational numbers (which includes integers) or inexact floating point numbers (presumably, they're disambiguating this by whether or not you use a decimal point).
- mgraczyk 12y ago
  Nice. Still, it's unsettling that they've confounded address space size with integral type width.
  - dragonwriter 12y ago
    Available RAM (something 8GB plausibly could refer to, unlike address-space size) is arguably more relevant to the issue here (which is the desirability of not using fixed-width integers and floating point but instead preferring arbitrary-precision rational numbers as the default.)
    - shriramkmurthi 12y ago
      That is indeed our point. Thanks for explaining it!
fineIllregister 12y ago
In Pyret, (1 / 3) resolves to (1 / 3), not 0.3333333333333333 or some equivalent, like it does in many other languages. (0.3333333333333333 * 3) is 0.999999999999999, not 1.
- mgraczyk 12y ago
  That makes sense, but unfortunately the Pyret page says nothing to indicate that arithmetic is done in the rational field. For the record, 1.0 compares equal to (1.0 / 3) * 3 in IEEE 754 32-bit floating point arithmetic. You may want to consider a more compelling example, ie float x = 1.0; for (int i = 0; i < 10; ++i) { x += 1.0 / 10; } x == 1.0 // False
  - shriramkmurthi 12y ago
    Sure. In general there are lots of examples that illustrate the ugliness of using floating points _unnecessarily_.

JonathonW 12y ago

From what I'm reading, Pyret numbers are either exact rational numbers (which includes integers) or inexact floating point numbers (presumably, they're disambiguating this by whether or not you use a decimal point).

mgraczyk 12y ago
Nice. Still, it's unsettling that they've confounded address space size with integral type width.
- dragonwriter 12y ago
  Available RAM (something 8GB plausibly could refer to, unlike address-space size) is arguably more relevant to the issue here (which is the desirability of not using fixed-width integers and floating point but instead preferring arbitrary-precision rational numbers as the default.)
  - shriramkmurthi 12y ago
    That is indeed our point. Thanks for explaining it!

fineIllregister 12y ago

In Pyret, (1 / 3) resolves to (1 / 3), not 0.3333333333333333 or some equivalent, like it does in many other languages. (0.3333333333333333 * 3) is 0.999999999999999, not 1.

mgraczyk 12y ago
That makes sense, but unfortunately the Pyret page says nothing to indicate that arithmetic is done in the rational field. For the record, 1.0 compares equal to (1.0 / 3) * 3 in IEEE 754 32-bit floating point arithmetic. You may want to consider a more compelling example, ie float x = 1.0; for (int i = 0; i < 10; ++i) { x += 1.0 / 10; } x == 1.0 // False
- shriramkmurthi 12y ago
  Sure. In general there are lots of examples that illustrate the ugliness of using floating points _unnecessarily_.