• click on the system menu and chose Close,
• in the File menu, chose the Quitt command,
• click the close button at the top-right of the window,
• press simultaneously the Alt and F4 keys.

Calling help

You can get help (sorry in french...) either through Help menu, or by clicking the button with a question mark, or by pressinf the F1 key (in this case you have a contextual help: it depends on the current situation when you press the key).

Some useful commands for edition.

• File - New Browser:   creates a new edit window (called "browser"), you can open several such windows (there will be no link between them).
• File - Open: to open an existing file in the active "browser", the name of the window is changed to the file name.
• File - Save (under) to save the content of the active browser in a file, you can change the name of the file in the ``under" case;.
• Edit - Copy/Cut/Paste These commands are standard ones in text editing. After having selected a piece of text *, Copy and Cut allows respectively, and as the name says, to copy the selected text in memory and let it there (Copy), or delete it (Cut). Paste allows then you to insert the last copied or cutted piece of text to the current cursor position.

• File - Clone allows you to open a clone of the active edit window, every change in one of the clones will affect all the others (it is not the case if you open two browsers with the same file in them). This is useful for exampel if you want to look at the text of a variable definition when you define another one.
• Options - To Text mode With this you can see the file linearly, expressions appear one after one. The order is the one of the file. If the text mode is activated, thsi command becomes: Options - To Browser mode and of course it allows you to come back to starting mode.
• Screen - Tile disposes the screen and displays all the opened windows with the same size.
• Screen - Tile 1/3 disposed the Winscm window with 1/3 of height for the interpreter window and 2/3 for the active edit window.

The interpreter in the environment

In this window, and only in this one, you can evaluate expressions: it is the window of the language, other windows are only for edition.

The interpreter took place in the Winscm window. You can display it in full screen by pressing simultaneously the Alt and Enter keys (when this window is active). You go back in the same way.

Working session example.

This example will illustrate, among other things, the links between the edit area and the interpreter area. We will discover too the main fonctionnalities of the software. You may have more information by reading the help (in french).

Open a file

In this session, we will work with a still begun program. Therefore we first have to open the file containing this program. This can be done by activating the command Open of the File menu, or by clicking on the button with an open folder on it, or else by activating the contextual menu of the variables area and chosing open.

Then a window opens, which asks you to chose your file (FIG 2). The one we are interested in is in the c:\winscm95\travail directory. Its name is exemple1.scm.

Then, you have to select the right directory in the directory area, then to double-click on the program name in the program names area. Then the file opens. You can see the list of defined objects which appears in the variables area.

Access to code

By clicking on one of the name (we should say identifier), the text (or code) that defines it appears in the edit area.

Let us click on the identifier cub (FIG 3). Its definition appears in different colors and lines are indented with a convention that will be explained later. The code for color is the following:

• green : predefinite variables (listed in custom\index.scm file) ;
• blue: user defiined variables in this file ;
• red :round brackets;
• mauve : local variables defined with define ;
• black : other symbols(constants, parameters, etc.).

Definition of a new variable

To define a new variable, you can use two ways:

The edit window becomes empty; you can now enter the code of the new variable to define. Enter the next code (even if you do not understand it at now - but it should not look so strange...) which defines the new variable carre+1:

(define carre+1
(lambda (x)
(+ (carre x) 1)))

Maybe have you noticed that when you type a closing round bracket, the corresponding opening one flashed (this may be too fast on some PC). Moreover, at the left of the status bar (bottom of main window) appears the beginning of the expression you have finished with this closing brackets. This proves to be necessary when you have imbricated expressions. You will quickly be convinced.

You probably have noticed too that indentation is automatically performed; its goal is to improve the readibility of programs. You will soon be aware that this is a great help when you have quite long definitions. The indent convention is the following: the sub-expressions of an expression are lined the one under the others (but you have to insert a end of line - Enter key - between each).

Save work

There are two different steps. To distinguish them, we will name the first one by ``store'' and the second by ``save''.

First, we have to do such that the variable will be effectively defined in the file. Store is performed atomatically if the Enter key is pressed after the last bracket of the definition. Anoter solution is to right-click in the edit area and to chose the Store command. A heading appears when the variable is stored if the Heading option of the contextual menu of variables area is activated. It is to facilitate the writing of comments.

If an error is detected (not every synatx error is) during storage, a warning appears. You can still store the text, the name of the variable appears then in red. It could be corrected later.

To save the file, you have to use either Save or Save under of File menu, or click on the the button with a disk on it. The Save under command allows you to change the file name (FIG 5).

For example, you can save the current file under the new name (monfichier.scm par exemple). Let us note that the extension ``.scm'' is added by default. The edit window took the name of the file.

Interaction edit window-interpreter

It is important to be aware that at now, since no interaction between edition and the interpreter has occured, objects defined in the file we have opened are not known by scheme. To convince you, it suffices to try to evaluate the expression (carre+1 2): an error occurs. This told you that the identifier carre is unknown. Indeed, every variable must be defined in the interperter if you want to evaluate (and then to use) it.

If you want the variable carre+1 to be known by scheme, you must make scheme evaluate its definition. A way is to select the variable in the variables area, then to activate the contextual menu in the edit area (remember, it is by right-clicking) and then to chose the Evaluate(FIG 6) command. Another way is to click on the button with the balloon. This evaluation is automatically performed when storing if the Auto option of the contextual menu of variables area is activated.

In each case, we notce that something happens in the interpreter window. Indeed, the code of the definition of carre+1  has been transmitted to scheme. This is similar as if the definition (define carre+1 (lambda ... )) had been written in the interpreter window. Then Scheme has evaluated and thus know this identifier, we will check that.

Let us try to evaluate the expression (carre+1 1) again... Another error occurs~! But this time, this is the carre variable which is unknown. This is indeed used in the definition of carre+1. But, the carre must have been defined -in Scheme- before any use of its identifier. Therefore we have to evaluate the definition of carre too, this can be done in the same way as for carre+1.

Once it is done, the evaluation of (carre+1 1) is at last possible without error and the result is returned.

Now if we want to use the variable cube, we should have to redo the same with this variable and so on for each one. This could quickly become tedious. Happily, there is another solution. It consists in to activate the contextual menu of the variables area (FIG 7) and to chose the Evaluate all (as well available in the Functions menu). In this cas, all the variables defined in the file (i.e. whose names appear in the variables area) are evaluated. Therefore they can all be used.

It is of course possible to write expressions which are not definitions. These expressions appear in the variables area under the names !divers_1, !divers_2, etc. in chronological order of writing. (FIG 8).

To evaluate a !divers_1 expression, you have to select the expression in the edit window (by highlighting it) and then to chose evaluate in the contextual menu.

It is possible to delete an expression by selecting its name and chosing Delet in the contextual menu of the variables area.

Importing variables

It happens sometimes that you need a variable you have alreaduy defined in an other file. For example, let us imagine you need the deuxX2+1 variable defined in the file C:\winscm95\travail\exemple2.scm. To rewrite it is a loss of time... To avoid that, it suffices to activate the Insert variable command of the File menu. Then, you just have to chose the file which contains the variables to reuse (for our example it is exemple2.scm), then in the list of variables that appears, you just have to click (once) on each variable, then to open the contextual menu of this window and chose Select. It is as well possible to insert a whole file with the Insert command of File menu (FIG 9).

Imported variables appears now in the variables area of exemple1.scm. You now have to evaluate them in order to use them.

Let us note that it is possible to import a variable directly from another open browser simply by "drag and drop" of its identifier: click (and let the button down) on the name of the variable in the source variables area and move the mouse pointer (still with button down) until the target variables area then release the button.

Modifying definitions order

In "text mode", you have to use "cut/paste". In ``browser mode'', you have to select the variable to move, activate contextual menu, chose Move. Then, select the variable before ou after which one you want to move and chose Move Before or Move After (FIG 10). Else, you can chose Cancel Move.

Leaving an edit window

To leave an edit window, it suffices to double-click on its close button. Try it. Do you have thought to save it? Happily, if not, a message warned you! In a general way it is a good habit to regularly save your work: an unwilling crash of the computer may happen...

Save on a floppy disk

To save on a floppy disk, you must select the Save under command of File menu. And then in the drive area, chose the floppy drive (often its name is A: or B:). And last, give a name to the file in the file name area.

Restarting the interpreter

If for some reason, a problem occurs with the interpreter an its window is destroyed or becomes unmanageable, it is possible to restart it by chosing the command File - Reinit Scheme. You will then eventully have the choice between several interpreters, chose one by double clicking on it. (FIG 11).

Notes :

There is a small problem with the version under Windows 95 when you close the application : you have to click OK when a message appears. This has no consequence but we cannot solve the trouble. [back]

To select a piece of text, you must put the cursor at the beginning of the piece, then by holding the left button down, move the cursor until the end of the piece of text and then let the button up (the text is highlighted).[back]

scheme@lifl.fr: pour plus d'informations.

routier@lifl.fr