Lists


 

 

4.6.1 Lists

TBoS p.63-73, SD

Lists in Shen are produced by placing the items in square brackets. The list of the numbers 1, 2 and 3 is just [1 2 3]. 'head' and 'tail' take the head and tail of a list.

[1 (+ 1 1) (+ 1 2)]
[1 2 3]

(head [1 2 3])
1

(tail [1 2 3])
[2 3]

'cons' adds an element to the front of a list. Shen includes an infix | which works in the manner of Prolog; '[1 2 | [3]]' conses 1 and 2 to the list [3]. If the second argument to 'cons' is not a list then the result is a dotted pair in Lisp jargon.

(cons 1 [2 3])
[1 2 3]

[1 2 | [3]]
[1 2 3]

[1 | (+ 1 1)]
[1 | 2]
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

Built by Shen Technology (c) Mark Tarver, September 2021