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"
Development
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.{{Cite web |title= Formula Engine Rewrite |author= Damien Katz |url= http://www.damienkatz.net/2005/01/formula-engine-rewrite.html |work= Personal blog |date= January 4, 2005 |accessdate= September 30, 2016 }} New features were added to the language, such as looping and dynamic execution, and performance was improved.{{Cite web |title=Enhancements to the formula language in Domino 6 |date= November 4, 2002 |url= http://www.ibm.com/developerworks/lotus/library/ls-formula_enhancements |url-status= dead |archiveurl= https://web.archive.org/web/20121022162650/https://www.ibm.com/developerworks/lotus/library/ls-formula_enhancements/ |archivedate= October 22, 2012 |publisher= IBM |accessdate= September 30, 2016 }}
Structure
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.