notes

20200926010452-trans_flag.org

@@ -0,0 +1,6 @@
+#+title: Trans Flag
+
+* Colors
+- Maya Blue :: Hex: =#55CDFC=, RGB: =(85, 205, 252)=, CMYK: =0.662, 0.186, 0, 0.011=
+- White :: Hex: =#FFFFFF=, RGB: =(255, 255, 255)=, CMYK: =0, 0, 0, 0=
+- Amaranth Pink :: Hex: =#F7A8B8=, RGB: =(247, 168, 184)=, CMYK: =0, 0.319, 0.255, 0.031=

20201007142751-python_typing.org

@@ -1,10 +1,12 @@
 #+title: Python Typing
+#+LINK: pep https://www.python.org/dev/peps/pep-%s/
 
 Python does not require nor enforce strict typing, and instead takes a dynamic
 approach using [[file:20201008164244-duck_typing.org][Duck Typing]].
 
-Optional [[file:20201008164835-structural_typing.org][Structural Typing]] support for Python is provided via type hints as
-described in [[https://www.python.org/dev/peps/pep-0484/][PEP-484]].
+Optional [[file:20201009010321-static_type_checking.org][Static Type Checking]] support for Python is provided via type hints as
+described in [[pep:0484][PEP-484]] (which covers [[file:20201009010657-nominal_typing.org][Nominal Typing]]) and expanded upon in [[pep:0544][PEP-544]]
+(which covers [[file:20201008164835-structural_typing.org][Structural Typing]]).
 
 Variables, function arguments, and return values can have their types annotated,
 e.g. "variable x has type integer" or "function y takes a string and returns a
@@ -22,4 +24,20 @@ program correctness.
 - Type hints do not guarantee purity.
 - Type hints are not checked at run-time.
 * Fun facts
-- Python's =boolean= inherits from =int=, hence =True + True = 2=.
+- Per [[pep:0285][PEP-285]], Python's =boolean= inherits from =int=, hence =True + True = 2=.
+* Relevant PEPs
+- [[pep:0482][PEP 482 -- Literature Overview for Type Hints]]
+- [[pep:0483][PEP 483 -- The Theory of Type Hints]]
+- [[pep:0484][PEP 484 -- Type Hints]]
+- [[pep:0526][PEP 526 -- Syntax for Variable Annotations]]
+- [[pep:0544][PEP 544 -- Protocols: Structural subtyping (static duck typing)]]
+- [[pep:0557][PEP 557 -- Data Classes]]
+- [[pep:0560][PEP 560 -- Core support for typing module and generic types]]
+- [[pep:0561][PEP 561 -- Distributing and Packaging Type Information]]
+- [[pep:0563][PEP 563 -- Postponed Evaluation of Annotations]]
+- [[pep:0585][PEP 585 -- Type Hinting Generics In Standard Collections]]
+- [[pep:0586][PEP 586 -- Literal Types]]
+- [[pep:0589][PEP 589 -- TypedDict: Type Hints for Dictionaries with a Fixed Set of Keys]]
+- [[pep:0591][PEP 591 -- Adding a final qualifier to typing]]
+- [[pep:0604][PEP 604 -- Allow writing union types as X | Y]]
+- [[pep:0613][PEP 613 -- Explicit Type Aliases]]

20201008164835-structural_typing.org

@@ -10,10 +10,5 @@ types are equivalent and whether a type is a subtype of another.
 --- https://en.wikipedia.org/wiki/Structural_type_system
 #+end_quote
 
-* Benefits
-** Easier reasoning
-Types make it easier to reason about code, as they describe succinctly what a
-function can do. If a function takes a single string as an argument and returns an integer, there's only so many things
-** Error reduction
-While types are not a substitute for testing, they do obviate a class of tests
-that you have to write yourself.
+Structural type systems can achieve [[file:20201009010321-static_type_checking.org][static]] [[file:20201008164244-duck_typing.org][Duck Typing]], in that a type's
+structure is what determines its suitability, not its name.

20201009010321-static_type_checking.org

@@ -0,0 +1 @@
+#+title: Static Type Checking

20201009010657-nominal_typing.org

@@ -0,0 +1,10 @@
+#+title: Nominal Typing
+
+#+begin_quote
+Nominal typing means that two variables are type-compatible if and only if their
+declarations name the same type. For example, in C, two struct types with
+different names in the same translation unit are never considered compatible,
+even if they have identical field declarations.
+
+--- https://en.wikipedia.org/wiki/Nominal_type_system
+#+end_quote