Expressions and programs

In the Flow Connect platform, FlowScript is variously used as an expression language, a template language and a programming language. The purpose of this section is to give you a feel for what these three categories mean.

Expression language

FlowScript is used as an expression language in, among other places, Assertion steps and Decision steps, when defining custom conditions.

An Assertion step demonstrating the use FlowScript expressions to specify custom logic in an application.

An expression is a string of symbols that denotes some value.

• The expression numberOfItems denotes the value of some variable called "numberOfItems".

• The expression 1 denotes the number one.

• The expression numberOfItems < 1 denotes a truth value indicating whether a variable named numberOfItems contains a number that is less than the number one.

Template language

A template in Flow Connect is a way to specify text that may contain the values of expressions.

In the screen shot below, a Header item in a User step has been configured to display the template Hello, {name}! in which the curly braces contain an expression referring to some variable called "name", assumed to have been created by some previous step. When the application is run, the expression surrounded by curly braces will be replaced by the value of the variable name. If the variable contains the text "Annie", the header will read "Hello, Annie!".

A user step demonstraing the use of FlowScript templates to customize text on the screen.

Programming language

In script steps, the full possibilities of the FlowScript language become available. Unlike expressions and templates, script steps allow you do declare variables, write conditional blocks, define functions, loop over sequences and more.