records system (builds on type-system-j)
this project uses typesystem-j https://github.com/Pascal-J/type-system-j
It enhances J, with record data structures that can be used to provide multiple parameter functions with type validated and coerced paramters, as well as pre and post function call validation.
It is powerful enough to create single line GUI calls, and is one of the main benefits provided by a dynamic type system. Also provided is a GUI builder to create records and forms
The form generator/system is provided for Jqt, but any backend including the web can be provided with the same creation interface.
New technologies include:
##type system
A type is a named classification function (returns boolean) on data. Validators return errors when the classification result is false. Coercers transform the data when the classifier is false such that the classifier would return true. A simple type is num. It is false when evaluated on a string, but can be attempted to be converted. Maybenum is a more powerful type in that as a coercer '123' and 123 becomes a number, while 'abc' does not. Maybenum coerced type, can be followed up with a num validated type such that both the inputs '123' and 234 are valid, and accepted by a function that operates on numbers.
types are easily created with a single line entry in a datadriven interface including documentation and error reporting. Additional useful type manipulation functions are described in the typesys page linked above. typesys-J is more powerful and flexible than any other programming language type system. It works without modifying the raw data, and so is a completely optional modifier to functions that operate on any data.
##record system
records are not only useful for database applications, but they also model traditional language function signatures. Records are made up of fields that can each have a type interaction (default values are part of the type system coercers). An optional pre-coercer function (often to fill input with nulls if too few parameters are passed) operates before each field is typechecked, and an optional post validator can evaluate whether the entire record is valid after coercion steps. Each field has a an optional sequence of coercers that runs before an optional sequence of validators.
records are objects that contain no data. Instancing a record simply creates accessor verbs, and coercion and validation functions, and so provides 0 overhead/cost to the data, when not used. Furthermore, literal accessor functions get "compiled away" into tacit J code.
##record builder
record definitions including all of the individual field and whole record processors can be built from a single string thanks to a "multicut" function that is also one of the system defined type system coercers. multicut is similar to csv parsing, except that multiple user defined nested delimiters are used to produce nested boxes. ','&multicut boxes first by separator, then inside those boxes again by ','. Using a multicut coercer allows a function that expects boxed input to receive a single string. The record builder is an example of such a flexible function. There is an accompanying unmulticut to create delimited strings from boxes. The system can interchangeably use deeply nested box structures and a string representation of those. String representations tend to be easier to craft through typing, and take up less memory.
##recordform also built from single line, that is either a record building string or record instance as right parameter, and some form specific parameters (boxed or in multicut format) as left parameter. A recordform will callback a provided function, once all of the recordfield inputs are valid. A recordform "control" is a vertical grid space (Jqt term that could easily be replaced by a html table row) that renders a record field, including space for help regarding the field (also defaults as tooltip content), that serves double duty for reporting field validation errors. the form building parameters primarily provide this info, and also provide optional starting values for the fields.
This is a major motivator for the very powerful record system. Recordforms provide a visual interface to any function. It is also a powerful and relatively easy means of explaining a function/process. Recordforms are also useful in sequencing several function calls from a single parameter collection.
##recordform controls edit - default standard input box. can pass edit password to have input masked. passw - input box with password mask, with additional mask checkbox that makes the mask optional. ignore"[0|1] - standard input box with checkbox labeled ignore. when ignore is checked, callback function will be passed null for this parameter. This is useful for using internal default parameters, while letting the user have a default alternate value, and letting the user save his input but have it ignored. The 0|1 modifier is the initial setting for the checkbox. clear"[0|1] - standard input box with additional checkbox labeled clear. When clear is checked, the field will revert to starting value upon valid submission (OK, with no error in callback) checkbox["0|1] - used for 0/1 numeric input.
Forms can have an html console attached to them. All data is automatically formatted with a caption, column headers (if table), and ranked and boxed data is printed reasonably. This is implemented with an edith control. Stylesheets useable by a webview control are embedded in the code. A webview implementation is prettier, and may be faster as the console output grows. Webview is not yet compatible with android. The html console is an easy way of communicating the results of the callback function back to the user.
Additional buttons may be added to forms. These may ignore the form validations (do their own inside callback, or for simple unrelated launchers) or only trigger if same validations pass as ok button.
##freeform (micro) database
Partly a toy application, but remarkably useful.
functional database. right parameter to all functions is table stored in a noun. All functions return new data.
functional approach allows console input of every data operation
empty database is i.0 0
No field definitions. Number of fields is number in longest record.
All data is Maybenum: number or string automatically determined.
All fields are lists or null. Lists can be mixed type.
Simple query mode is any field contains any query item (OR within field), and AND between fields. Unspecified fields are ANY.
A not version of simple query is also convenient.
Selection may also be done by indexes.
Edits are done through update_first function. The first item in filter is updated as if adding a new item.
Delete first matched filter item is convenient.
Mass updates are done through update_verb. Each filtered item is passed to a dyadic J verb which can modify any field based on record. The default left verb parameter is the full table, but can be replaced with a provided one. See SAMPLES at bottom of todo.ijs for example update functions.
Mass deletes are done by saving filters.
A recordform GUI allows all database operations from the same form. Possible due to functional structure. The GUI adds the ability to switch to any variable, save filters as data, or just use them as views, save to disk, viewlimits, and use custom functions based on a domain. 2 variations of the ffdb are found in todo.ijs. One uses '`,' as field delimeters. The other uses '|,'. Datafiles are saved in boxed format, and so either interface can be used on data.
##GUI form builder A GUI form builder is also provided that uses a recordform to create the one line form creation commands for your own forms. A preview button launches the generated form automatically. The fields button is a bit of a toy, but it launches another GUI builder that uses the freeform database editor to add to and modify to the field list. While this isn't strictly necessary as the master form has a convenient line editor for the same purpose, it does show how to create master-sub form relationships (for one to many or other subform purposes), and shows cross form communication updating fields and console area of the master from from subform edits.
Place all files in same folder then, load 'todo.ijs' NB. add path formbuilderception can be achieved by graphically editing a version of the formbuilder with this command:
f =. New_formbuilder_ buildFPsample_formbuilder_ a:
f =. New_formbuilder_ a: NB. blank form builder
f =. New_formbuilder_ FP_123456_ NB. form builder restarted from previous saved parameters (auto saved to FP_var in previous form OK callback).
start__r a: [ r =:'f' DEF_recordform_ 'one;two' NB. creates and displays a 2 field form with no titlebar or prompt, and that will display result in J console.
go_todo_ a: NB. sample combination todo, calendar, project management toy. Shows self-defined datatypes, and how you might query it. Specialized functions such as Purge_old will decrease all times by 24 (or specified hours). Highlights how clear/ignore controls work, and their convenience. Can load new databases without form restart by changing variable, so used directly from base class instead of instancing. Superfast data entry interface.
the project at https://github.com/Pascal-J/rabin-key-gen uses recordforms to create encryption keys, and is an example of collecting many parameters so as to run multiple function sequences. The keygen.ijs file also shows a coding style for multiline definitions of forms that are more readable if not using the formbuilder to read/edit them.
current release works in j803 and j804, Previous versions worked in j802 as well. small todo: actively erase more objects.