Pico is a

programming language A programming language is a system of notation for writing computer programs. Programming languages are described in terms of their Syntax (programming languages), syntax (form) and semantics (computer science), semantics (meaning), usually def ...

developed at the Software Languages Lab at

Vrije Universiteit Brussel The Vrije Universiteit Brussel (Dutch language, Dutch, ; lit. Free University of Brussels; abbreviated VUB) is a Dutch- and English-speaking research university in Brussels, Belgium. It has four campuses: Brussels Humanities, Science and Engine ...

, 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 Semantics is the study of linguistic Meaning (philosophy), meaning. It examines what meaning is, how words get their meaning, and how the meaning of a complex expression depends on its parts. Part of this process involves the distinction betwee ...

. 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 In computer science, functional programming is a programming paradigm where programs are constructed by Function application, applying and Function composition (computer science), composing Function (computer science), functions. It is a declarat ...

style.

Comments

Comments are surrounded by backquotes ("`").

Variables

Variables Variable may refer to: Computer science * Variable (computer science), a symbolic name associated with a value and whose associated value may be changed Mathematics * Variable (mathematics), a symbol that represents a quantity in a mathemat ...

are dynamically typed; Pico uses static scope. var: value

Functions

Functions, like everything in Pico, are

first-class object In a given programming language design, a first-class citizen is an entity which supports all the operations generally available to other entities. These operations typically include being passed as an argument, returned from a function, and ass ...

s, 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 String or strings may refer to: *String (structure), a long flexible structure made from threads twisted together, which is used to tie, bind, or hang other objects Arts, entertainment, and media Films * ''Strings'' (1991 film), a Canadian anim ...

integer An integer is the number zero (0), a positive natural number (1, 2, 3, ...), or the negation of a positive natural number (−1, −2, −3, ...). The negations or additive inverses of the positive natural numbers are referred to as negative in ...

, 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 In mathematical logic, the lambda calculus (also written as ''λ''-calculus) is a formal system for expressing computability, computation based on function Abstraction (computer science), abstraction and function application, application using var ...

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

MacPicoXPico

Windows

''This version is buggy''
WinPico stable

Linux

TextPico for Linux

Cross-platform

sPico for DrScheme

References

External links

*
Software Languages LabDepartment of Computer Science at VUBVUBThe Infogroep Pico page
{{Lisp programming language 1997 software Programming languages created in 1997 Programming languages Functional languages Educational programming languages Academic programming languages Dynamically typed programming languages Lisp programming language family