paulsonkoly / calc Goto Github PK

it would be useful to be able to debug calc with a repl started at a given point in the program. A new built in function repl() would start a repl in the context of the call. When the repl exits the execution of the original script resumes. One can print values of variables and with that debug calc.

As the repl would be a function, it would be running its own frame so variable writes from it would be lost when it returns. Also its return value should be no value error, same as a loop value that never entered the loop body.

It would be useful to support string type.
String operations would be the same as array operations. (indexing and concatenation)

At this point the builtin read function should be re-thought. It probably should just return a string, and we should add builtin functions for type conversions as more built in functions between strings and non strings.

a = read()
a = atoi(a)

It could be useful for the user to create it's own error type. Probably only becomes useful if strings are supported.

New built in function error takes a string (error message) and returns an error.

 f = (n) -> if n == 0 error("whoops") else 10/n

In order to be more useful calc should support array type.

At the minimum array type should have the following concepts:

• array literal
• indexing with single index
• indexing with range
• array concatenation

The syntax could be whats implied by the following example:

filter = (pred, ary) -> {
  i = 0
  r = []
  while i < #ary {
    if pred(ary@i) r = r + [ary@i] 
    i = i + 1
  }
  r
}

qsort = (ary) -> {
  if #ary == 0 ary else {
    pivot = ary@0
    qsort(filter((n) -> n <= pivot), ary@1:)) + [pivot] + qsort(filter((n) -> n > pivot, ary@1:))
  } 
}