Frequently the answer is no, you don't need to change every function. If you're iterating through values, are obtaining the lookup value outside the function, or just passing it along, no changes are necessary.
Compared with your average statically typed language, you do have to update the function signature and everything that calls it.
Now then, admittedly, Haskel is not your average statically typed language - but then again it's very rare to actually run up against Haskel in production code.
I don't think you can iterate thought the values in an array and in a dict in e.g. python with the exactly same syntax.
That depends on what you mean by "values". The default iterator over dictionaries in python iterates over the keys, so if you use the exact same syntax as iterating over members of a list you iterate over the keys of a dictionary, not what are usually called the values (there is a separate iterate for that, and for key/value pairs). But, yes, dicts and lists are iterable via the same syntax since they both support Pythons iteration protocol.
I don't think you can iterate thought the values in an array and in a dict in e.g. python with the exactly same syntax.
just passing it along
In languages with global type inference (e.g. OCaml) you would not have written the type in the code in the first place, so changing the type of an argument that you just pass through, would not require any changes in the code.
But yes, in Haskell people are in the habit of writing the type signatures, even though the compiler does not require them, so in this case edits are needed.
Comments
Frequently the answer is no, you don't need to change every function. If you're iterating through values, are obtaining the lookup value outside the function, or just passing it along, no changes are necessary.
Compared with your average statically typed language, you do have to update the function signature and everything that calls it.
Now then, admittedly, Haskel is not your average statically typed language - but then again it's very rare to actually run up against Haskel in production code.
That depends on what you mean by "values". The default iterator over dictionaries in python iterates over the keys, so if you use the exact same syntax as iterating over members of a list you iterate over the keys of a dictionary, not what are usually called the values (there is a separate iterate for that, and for key/value pairs). But, yes, dicts and lists are iterable via the same syntax since they both support Pythons iteration protocol.
I don't think you can iterate thought the values in an array and in a dict in e.g. python with the exactly same syntax.
In languages with global type inference (e.g. OCaml) you would not have written the type in the code in the first place, so changing the type of an argument that you just pass through, would not require any changes in the code.
But yes, in Haskell people are in the habit of writing the type signatures, even though the compiler does not require them, so in this case edits are needed.