Formula language

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The Formula language is a scripting language used by Lotus Notes. It is often referred to as @Formula language (pronounced at-formula) because many language elements start with the @-character. Here is an example of a selection formula:

SELECT @NoteId = "NT0050D26"

It was created by Ray Ozzie during the early development of Lotus Notes. He borrowed the compiler and decompiler from the Lotus 1-2-3 spreadsheet, but unlike the spreadsheet language Formula Language was designed primarily for string and list processing, not numerical processing. It was originally a Functional programming language with unique text list-handling features inspired by Ray Ozzie's prior use of Icon and Lisp.

The Formula language engine was rewritten by Damien Katz for Notes and Domino 6.^[1] New features were added to the language, such as looping and dynamic execution, and performance was improved.^[2]

The Formula language has two parts:

• @Functions for calculations and simple logic
• @Commands for performing actions in the user interface

@Functions can be used in several places throughout Lotus Notes. The most important uses are:

• to select documents to show to the user in a view (a kind of index) or to select documents for further processing. In this case, the formula will evaluate to a 'true' (selected) or 'false' value (not selected) for each document.
• to provide default values for fields, to transform the data entered by the user (like stripping off redundant spaces) and to validate this data.
• to get a list of values from a Notes database or even from a relational database (using ODBC). This may be used to provide a user with a list of values to choose from.
• to process a set of documents. The formula is placed in an agent, a program or macro that can be started by a user or by the Notes server according to a schedule. When the agent is triggered, the formula executes for each selected document (this a very limited form of a loop). This is an efficient way to change many documents, if the logic is not too complicated. In case of complicated changes, LotusScript is used.

@Commands are like menu commands: they perform actions in the Lotus Notes client. Examples of actions are:

• opening a Notes database
• creating an e-mail
• putting the cursor in a specific data-entry field
• closing a window
• starting an agent

@Commands are primarily used in formulas that are triggered by user action, such as in button formulas. It is possible to combine them with @Functions, for example by making execution of an @command conditional on a field value.