4.11 I/O
TBoS p.113-121, SD
The basic read and write operations in Shen are constructed on top of two primitives of Kλ called
'read-byte' and 'write-byte' which take a stream as an argument. If no stream is given then these functions take
the standard input and the standard output as default arguments. All other I/O system functions are built from these
two primitives. These include
|
Type | Functions | Comments |
|
Input | read-byte, read,
lineread, input,
input+ | (note all of the preceding take a stream as an optional argument
which if not specified becomes the standard input) |
|
Input | read-file,
read-file-as-bytelist,
read-file-as-string | |
|
Output | write-byte, pr | (note all of the preceding take a stream as an optional argument which if not specified
becomes the standard output) |
|
Output | nl, output, print, write-to-file | |
The functions are covered in the glossary of functions. In brief
|
Function | Description |
|
input | takes the user input and evaluates it. |
|
input+ | takes a type and a stream as an input and type checks the user input according to the type.
If a type error is found, an exception is raised otherwise behaves as input. |
|
lineread | reads the user input and when the input is terminated by a new line, returns the list of parsable
tokens of that input. |
|
nl | takes a non-negative integer n and prints n new lines. If none is given prints a single new line. |
|
output | takes the same input as make-string and returns the same output but as a side-effect prints the
resulting string. |
|
pr | takes a string and a stream and prints the string to the stream. |
|
print | prints any object returning that object. |
|
read | takes the user input and parses it without evaluating the result. |
|
read-byte | takes a stream and reads the first byte off it. If the stream is empty returns -1. |
|
read-file | takes a file name (string) and returns the list of parsable tokens in it. |
|
read-file-as-bytelist | takes a file name (string) and returns the list of bytes in it. |
|
read-file-as-string | takes a file name (string) and returns the contents of it as a string. |
|
write-to-file | takes a file name f (string) and an expression e and writes the normal form of e to f
overwriting any contents. If e is a string, then the contents of e are written to f
without the outer quotes. |
(0-) (lineread)
1 2 3
[1 2 3]
(1-) (pr "hello world")
hello world"hello world"
(2-) (input)
(* 7 8)
56
(3-) (read)
(* 7 8)
[* 7 8]
(4-) (input+ number)
a
a is not of type number
(5-) (read-file "factorial.shen")
[define factorial 0 -> 1 X -> [* X [factorial [- X 1]]]] |
|
1. Introduction
2. License
3. History
4. The Core Language
4.1 Base Types
4.1.1 Symbols
4.1.2 Strings
4.1.3 Numbers
4.2 Function Applications
4.3 The Top Level
4.4 Arithmetic
4.5 Comments
4.6 Sequences
4.6.1 Lists
4.6.2 Tuples
4.6.3 Vectors
4.7 lambda and let
4.8 Global Assignments
4.9 Higher Order Functions
4.10 Lazy Evaluation
4.11 I/O
4.12 Loading Files
4.13 Streams
4.14 Exceptions
4.15 Hashing
4.16 Property Lists
4.17 Eval
5 Defining Functions
5.1 Partial Functions
5.2 List Handling Functions
5.3 String Handling Functions
5.4 Tuple Handling Functions
5.5 Vector Handling Functions
5.6 Guards
5.7 Backtracking
5.8 Writing in Kλ
5.9 Macros
6. Packages
7. Shen-YACC
7.1 Recognisor Generator
7.2 Semantic Actions
8. Shen Prolog
8.1 Sample Programs
9. Types
9.1 Types and Constructors
9.2 Functions and Types
9.3 Synonyms
10 Sequent Calculus
10.1 Recursive Types
10.2 Exotic Types
10.2.1 Dependent Types
10.2.2 Negative Types
10.2.3 Subtypes
10.2.4 The Type of All Sets
11 Glossary of Functions
12 The Syntax of Shen
|
