Lichen

Changeset

926:1429afa1fe50
4 months ago Paul Boddie raw files shortlog changelog graph Added some notes about the different type names. int-as-function
docs/wiki/Design (file) docs/wiki/Representations (file) docs/wiki/ToDo (file)
     1.1 --- a/docs/wiki/Design	Wed Jun 23 01:52:42 2021 +0200
     1.2 +++ b/docs/wiki/Design	Sun Jun 27 19:29:37 2021 +0200
     1.3 @@ -697,3 +697,38 @@
     1.4  the appropriate parameter of this nature, but programmers could just write
     1.5  functions and methods that employ general sequence and mapping parameters
     1.6  explicitly instead.
     1.7 +
     1.8 +== Library and Built-In Types ==
     1.9 +
    1.10 +{{{#!table
    1.11 +'''Lichen''' || '''Python''' || '''Rationale'''
    1.12 +==
    1.13 +Integers belong to the `integer` type
    1.14 +|| Integers are represented using the `int` type
    1.15 +|| The `int` callable cannot be used to construct integer values in Lichen
    1.16 +==
    1.17 +Strings belong to the `string` or `utf8string` types
    1.18 +|| Strings are represented using the `str` or `unicode` types
    1.19 +|| Separate `str` and `unicode` functions perform conversion to string types
    1.20 +}}}
    1.21 +
    1.22 +=== Integer Type ===
    1.23 +
    1.24 +In Python, the `int` callable is largely used to convert other types to
    1.25 +integers. However, it is also used to test whether instances are integers, and
    1.26 +the callable is, in fact, a form of constructor. Since Lichen only supports
    1.27 +the definition of initialisers (`__init__`) and not more exotic callables such
    1.28 +as `__new__`, which would permit more control over the construction of
    1.29 +instances, it cannot easily provide the necessary functionality to redefine
    1.30 +the nature of an instance, at least in the case of integers whose identities
    1.31 +are their values, which applies in Lichen because tagged values are used in
    1.32 +place of integer instances, and thus the "virtual" instance being initialised
    1.33 +would actually need to be exchanged instead of being changed in some way.
    1.34 +
    1.35 +=== String Types ===
    1.36 +
    1.37 +Similarly, in Python, the `str` and `unicode` callables both convert and
    1.38 +construct new instances as well as acting as types. Although an initialiser
    1.39 +could be written to mutate the value retained by such instances in Lichen,
    1.40 +this precludes the obvious definition of a `str` function as merely a wrapper
    1.41 +around the invocation of the `__str__` method of any given object.
     2.1 --- a/docs/wiki/Representations	Wed Jun 23 01:52:42 2021 +0200
     2.2 +++ b/docs/wiki/Representations	Sun Jun 27 19:29:37 2021 +0200
     2.3 @@ -54,12 +54,12 @@
     2.4  obtaining an instance under normal circumstances, instead provides the address
     2.5  of a common integer instance. This instance may then provide instance
     2.6  attributes, whose values will be the same for all integers, or class
     2.7 -attributes through a reference to the integer (`int`) class.
     2.8 +attributes through a reference to the `integer` class.
     2.9  
    2.10 -Each method provided by `int`, when called, will be given the original
    2.11 +Each method provided by `integer`, when called, will be given the original
    2.12  attribute for which the method was obtained as its context. In such methods,
    2.13 -operations on the context via `self` will either involve the propagation of
    2.14 -the attribute to other functions or methods or attribute accesses on `self`,
    2.15 +operations on the context via `self` will either involve the propagation of the
    2.16 +attribute to other functions or methods or attribute accesses on `self`,
    2.17  yielding common instance attributes or class attributes as already described.
    2.18  Only native functions will attempt to interpret the attribute in a different
    2.19  way, decoding the representation, performing arithmetic or logical operations,
     3.1 --- a/docs/wiki/ToDo	Wed Jun 23 01:52:42 2021 +0200
     3.2 +++ b/docs/wiki/ToDo	Sun Jun 27 19:29:37 2021 +0200
     3.3 @@ -14,14 +14,14 @@
     3.4  
     3.5  === Numeric Types ===
     3.6  
     3.7 -Support all the numeric types. Currently, only `int` is supported, but `float`
     3.8 -merely requires some native code handling operations and testing for exception
     3.9 -conditions. A representation for `long` needs to be determined, and `complex`
    3.10 -probably just needs some methods implementing.
    3.11 +Support all the numeric types. Currently, only `int` is supported (as
    3.12 +`integer`), but `float` merely requires some native code handling operations
    3.13 +and testing for exception conditions. A representation for `long` needs to be
    3.14 +determined, and `complex` probably just needs some methods implementing.
    3.15  
    3.16 -Support promotion between some of the numeric types. Currently, `int` values
    3.17 -that overflow raise `OverflowError`, as was done in Python before automatic
    3.18 -promotion to `long`.
    3.19 +Support promotion between some of the numeric types. Currently, `integer`
    3.20 +values that overflow raise `OverflowError`, as was done in Python before
    3.21 +automatic promotion to `long`.
    3.22  
    3.23  === String Types ===
    3.24