Programming Language A study note (a)

SML (i)

1. ML is a functional programming language with a theoretical basis for λ calculus.

2. Variable declaration

val x = e;

Standard types: cell (unit), Boolean (bool), integer (int), string, real (real), tuple (tuple), records (record), list

1) Negative numbers indicate that the minus sign is denoted by "~", and 1 means "to";

2) string: A sequence of characters between double quotation marks;

3) Real numbers: floating-point numbers in which other languages are expressed as double;

4) List: "[]" denotes empty list,list example: [1, 4, 9, 25],list, data types in the requirements of the same, can be nested;

5) Tuple: comma-delimited data elements in parentheses, can be nested, tuple data types can be inconsistent, for example: (A, 9);

6) Record: The values and types of records are written in {}, for example: {first:int, middle:int, last:int};

1	Meta-group	List	Recording
Brackets	()	[]	{}
Element type	can be different	Must be the same	can be different
Length	Fixed length	Variable length	Variable length
Type-expression	< element type > expression with * connection	< element types > List	{Record Name: < element type;}

3. Using the program file: Use "FOO.SML";

4. Function definition

The type of the function in SML is determined by his defined domain and range.

Sml	C language
Fun Division (X:int, Y:int) = X div y	int division (int x, int y) { return x/y; }

5. Tuple Data references

Tuple Pr:int * bool = #1 PR tuple first element, int type; #2 PR tuple second element, bool type;

6. List data references

HD, List header elements, lists other than TL,HD elements;

7. Let expression: Let B1 B2 ... bn in E end

B1 B2 ... bn can be a variable declaration, function definition, etc., E is an expression

8. Conditional expression: If E1 then E2 else E3

E1, E2, E3 are expressions, E2 and E3 require the same data type;

9. NONE, some and Valof

Key words	Evaluate	TYPE
' A		Any type
' A list		After any type of LIST;HD type is determined, the list type is fixed
NONE	NONE is a option value "carrying nothing" whereas	' A option
SOME E	SOME e evaluates e to a value V and becomes the option carrying the one value v.	T option if E has type T.
NULL, Issome	Null to see if a list is empty and we have issome which evaluates to False if its argumentis NONE.
Valof	Get the value carried by SOME (raising a exception for NONE)

10. Operators

Arithmetic plus, minus, multiply, divide: + 、-、 *, div (int),/(real type)

Logical operations and, or, non, equal, unequal, greater than, less than, greater than or equal to, less than or equal to: AndAlso, OrElse, not, =, <>, >, <, >=, <=

String Connection: ^

Two List connections: @

Data e and List es connection: e::es

Programming Language A study note (a)