2. Your first model

Declare a part, give it values, instantiate it and look inside — first by typing at the prompt, then from a file. Everything here is notation you would write in a .sysml file; the REPL is just a faster way to see it answer.

At the prompt

Launch the interactive REPL:

$ sysml
SysML v2 REPL — %help for commands, Ctrl-D to exit
sysml> 

Define a Simple Part

Library types such as Real are not in scope automatically — import them, exactly as a .sysml file would:

sysml> import ScalarValues::*;
✓ import ScalarValues::*

sysml> part def Wheel {
  ...>     attribute diameter : Real = 16.0;
  ...>     attribute width : Real = 7.5;
  ...> }
✓ part def Wheel

Each accepted declaration is echoed back as ✓ <kind> <name>. A brace opens a continuation (...>) that runs to the matching one — but a blank line ends the submission, so leave none inside a declaration you are typing.

Re-typing a namespace adds to the one already in the session, so package P { part def B; } after package P { part def A; } leaves both declared; an empty body (package P { }) is how you clear one. Anything a submission does drop is reported as a note: line — the members it no longer declares, the instances it invalidated (their IDs restart with the new model), and any %action/%state debugging session it ended. A debugging session over a declaration the submission did not touch keeps running.

Define a Vehicle

sysml> part def Vehicle {
  ...>     attribute mass : Real = 1500.0;
  ...>     part wheels : Wheel[4];
  ...> }
✓ part def Vehicle

Instantiate and Inspect

sysml> %instantiate Vehicle
✓ Created instance of Vehicle
  ID: 1
  Use %features Vehicle to inspect

sysml> %features Vehicle
Instance: Vehicle (ID: 1)
Features:
  mass = 1500.00
  wheels = [Instance(ID: 2), Instance(ID: 3), Instance(ID: 4), Instance(ID: 5)]
    diameter = 16.00
    width = 7.50
    diameter = 16.00
    width = 7.50
    diameter = 16.00
    width = 7.50
    diameter = 16.00
    width = 7.50

sysml> %instances
Instances:
  Vehicle (ID: 1)

Evaluate Expressions

sysml> attribute wheelCount = 4;
✓ attribute wheelCount

sysml> attribute totalDiameter = wheelCount * 16.0;
✓ attribute totalDiameter

sysml> %eval totalDiameter
✓ totalDiameter
  = 64.00

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From a file

Create a file my_model.sysml:

package MyModel {
    part def Sensor {
        attribute reading = 0.0;
        attribute threshold = 100.0;
    }

    part def System {
        part sensors : Sensor[3];
    }
}

Load it in the REPL. %load submits the file's contents as if you had typed them, so it reports the same ✓ lines; %list echoes everything the session currently holds:

$ sysml
sysml> %load my_model.sysml
✓ package MyModel

sysml> %list
package MyModel {
    part def Sensor {
        attribute reading = 0.0;
        attribute threshold = 100.0;
    }

    part def System {
        part sensors : Sensor[3];
    }
}

sysml> %instantiate MyModel::System
✓ Created instance of MyModel::System
  ID: 1
  Use %features MyModel::System to inspect

sysml> %features MyModel::System
Instance: MyModel::System (ID: 1)
Features:
  sensors = [Instance(ID: 2), Instance(ID: 3), Instance(ID: 4)]
    reading = 0.00
    threshold = 100.00
    reading = 0.00
    threshold = 100.00
    reading = 0.00
    threshold = 100.00

A composite feature lists the features of each of its objects under it, in order.

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Next: 3. From the command line, which runs these same checks without a prompt. The prompt itself is covered in 4. The REPL.