Pico (programming language)

For other uses, see Pico (disambiguation).

Pico
Paradigms	Reflective, procedural
Family	Lisp
Designed by	Theo D'Hondt Wolfgang De Meuter
Developer	Vrije Universiteit Brussel
First appeared	1995 (1995)
Stable release	2.0 / 2007 (2007)
Implementation language	Scheme
Platform	IA-32, x86-64
OS	Mac OS 9, macOS; Linux–BSD, Windows
Website	pico.vub.ac.be
Influenced by
Scheme, Smalltalk

Pico is a programming language developed at the Software Languages Lab at Vrije Universiteit Brussel, intended to be simple, powerful, extensible, and easy to read. The language was created to introduce the essentials of programming to non-computer science students.

Pico can be seen as an effort to generate a palatable and enjoyable language for people who do not want to study hard for the elegance and power of a language. They have done it by adapting Scheme's semantics.

While designing Pico, the Software Languages Lab was inspired by the Abelson and Sussman's book "Structure and Interpretation of Computer Programs". Furthermore, they were influenced by the teaching of programming at high school or academic level.

Pico should be interpreted as 'small', the idea was to create a small language for educational purposes.

Language elements

De Meuter, Gonzalez, and D'Hondt describe the Pico syntax as being "two-tiered." The first layer consists of simple rules for writing small programs in a functional programming style.

Comments

Comments are surrounded by backquotes ("`").

Variables

Variables are dynamically typed; Pico uses static scope.

var: value

Functions

Functions, like everything in Pico, are first-class objects, meaning they can be assigned to variables and passed to and returned from functions. Also, there are no anonymous functions in Pico; functions must have a name. For example, a function, func, with two parameters, param1 and param2, can be defined as:

func(param1, param2): ...

Functions can be called with the following syntax:

func(arg1, arg2)

Operators

Operators can be used as prefix or infix in Pico:

+(5, 2)
5 + 2

Data types

Pico has the following types: string, integer, real and tables.

It does not have a native char type, so users should resort to size 1 strings.

Tables are compound data structures that may contain any of the regular data types.

Boolean types are represented by functions (as in lambda calculus).

Control structures

Conditional evaluation

Only the usual if statement is included

if(condition, then, else)

Code snippets

display('Hello World', eoln)

max(a, b):
 if(a < b, b, a)

`http://www.paulgraham.com/accgen.html`
foo(n): fun(i): n := n+i

Implementations

Mac OS, Mac OS X

• MacPico
• XPico

Windows

• WinPico This version is buggy
• WinPico stable

Linux

• TextPico for Linux

Cross-platform

• sPico for DrScheme