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MEANS

Introduces the body of a function or decision. Connects a function name to its definition.

Syntax

name MEANS expression
DECIDE name MEANS expression

Purpose

MEANS separates the function signature (name and parameters) from its implementation (the expression that computes the result).

Examples

Example file:

-- MEANS keyword examples

-- Basic MEANS Usage

-- Simple value definition
greeting MEANS "Hello, World!"
answer MEANS 42

#EVAL greeting
#EVAL answer

-- Functions with MEANS

GIVEN x IS A NUMBER
double x MEANS x TIMES 2

GIVEN a IS A NUMBER, b IS A NUMBER
add a b MEANS a PLUS b

#EVAL double 21
#EVAL add 10 32

-- Multi-line Function Bodies

GIVEN n IS A NUMBER
GIVETH A NUMBER
factorial n MEANS
  IF n EQUALS 0
  THEN 1
  ELSE n TIMES factorial (n MINUS 1)

#EVAL factorial 6

-- MEANS with WHERE Clauses

GIVEN radius IS A NUMBER
circumference radius MEANS
  2 TIMES pi TIMES radius
  WHERE
    pi MEANS 3.14159

#EVAL circumference 10

-- Nested WHERE
outerFunction MEANS
  innerResult TIMES 2
  WHERE
    innerResult MEANS
      baseValue PLUS 10
      WHERE
        baseValue MEANS 5

#EVAL outerFunction

-- MEANS vs IS Comparison

-- Using MEANS for definitions
valueWithMeans MEANS 100
valueWithMeans2 MEANS 200

#EVAL valueWithMeans
#EVAL valueWithMeans2

-- MEANS in Complex Expressions

GIVEN items IS A LIST OF NUMBER
sumItems items MEANS
  CONSIDER items
  WHEN EMPTY THEN 0
  WHEN head FOLLOWED BY tail THEN head PLUS sumItems tail

#EVAL sumItems (LIST 1, 2, 3, 4, 5)

Basic Usage

greeting MEANS "Hello, World!"

GIVEN x IS A NUMBER
double x MEANS x TIMES 2

With DECIDE

DECIDE answer MEANS 42

GIVEN n IS A NUMBER
DECIDE square n MEANS n TIMES n

Multi-line Bodies

GIVEN n IS A NUMBER
factorial n MEANS
  IF n EQUALS 0
  THEN 1
  ELSE n TIMES factorial (n MINUS 1)

With WHERE Clauses

circumference radius MEANS
  2 TIMES pi TIMES radius
  WHERE
    pi MEANS 3.14159

Alternative Forms

Using IS

For simple definitions, IS can replace MEANS:

answer IS 42
DECIDE pi IS 3.14159

Using BE or MEAN

Alternative keywords (for isomorphism with legal text):

-- In LET expressions
LET x BE 5 IN x TIMES 2
LET y MEAN 10 IN y PLUS 1
  • DECIDE - Declares a decision
  • WHERE - Local definitions

Tutorials