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CS3110 Data Struct & Functional Programming

Ranting

When you find yourself saying, “I don’t know,” be sure to follow it up with “ - but I’ll find out.” It’s a great way to admit what you don’t know, but then take responsibility like a pro.

– The Pragmatic Programmer, Ch2. The Cat Ate My Source Code

From Textbook: Mutability

From Textbook: Specifications and Abstractions

Specification of Functions

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(** [f x] is ...
	Example: ...
	Requires: ...
	Raises: ... 
*)
let f x  = 

From Textbook: Code Reuse with Modules

Includes

Def: includes enables a structure to include all the values defined by another structure, or a signature to include all the names declared by another signature.

From Textbook: OCaml Modules

Structures

Semantics

The first letter of a module’s name should be capitalized.

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module ModuleName = struct 
  (* definitions *)
end

From Textbook: Higher Order Programming

Introduction

• higher-order: functions as values, you can pass functions as arguments into other functions, functions at the same level as other variables
• lower-order: languages like C, functions as something higher than other variables

Pipeline is a higher-order function.

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let pipeline x f = f x
let (|>) = pipeline
let x = 5 |> double  (* 10 *)

From Textbook: Advanced Data Types

Algebraic Data Types

以前我们的 variants 比较像 enum，但是现在我们更像一个abstract class

From Textbook: Standard Data Types

Lists

Building Lists

The empty list is written [] and is pronounced “nil”, a name that comes from Lisp. Given a list lst and element elt, we can prepend elt to lst by writing elt::lst. The double-colon operator is pronounced “cons”

From Textbook: Functions

Functions

Definition: let f x1 x2 ... xn = e (f is the function name; xi is input, and there can be multiple inputs; e is the output)

We can think of t1 -> t2 -> u as the type of a function that takes two inputs, the first of type t1 and the second of type t2, and returns an output of type u. Likewise for a function that takes n arguments.

A function is already a value (that’s how you assign the value “function” to a variable name), so there is nothing to be evaluated when we evaluate its dynamic semantic.