BERKELEY LOGO 6.1: 7 Workspace Management

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# 7 Workspace Management

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## 7.1 Procedure Definition

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### to

    TO procname :input1 :input2 ...			(special form)

command. Prepares Logo to accept a procedure definition. The procedure will be named procname and there must not already be a procedure by that name. The inputs will be called input1 etc. Any number of inputs are allowed, including none. Names of procedures and inputs are case-insensitive.

Unlike every other Logo procedure, TO takes as its inputs the actual words typed in the instruction line, as if they were all quoted, rather than the results of evaluating expressions to provide the inputs. (That’s what special form means.)

This version of Logo allows variable numbers of inputs to a procedure. After the procedure name come four kinds of things, in this order:

        1.   0 or more REQUIRED inputs    :FOO :FROBOZZ
        2.   0 or more OPTIONAL inputs    [:BAZ 87] [:THINGO 5+9]
        3.   0 or 1 REST input            [:GARPLY]
        4.   0 or 1 DEFAULT number        5

Every procedure has a minimum, default, and maximum number of inputs. (The latter can be infinite.)

The minimum number of inputs is the number of required inputs, which must come first. A required input is indicated by the

    :inputname

notation.

After all the required inputs can be zero or more optional inputs, each of which is represented by the following notation:

    [:inputname default.value.expression]

When the procedure is invoked, if actual inputs are not supplied for these optional inputs, the default value expressions are evaluated to set values for the corresponding input names. The inputs are processed from left to right, so a default value expression can be based on earlier inputs. Example:

    to proc :inlist [:startvalue first :inlist]

If the procedure is invoked by saying

    proc [a b c]

then the variable `inlist` will have the value `[A B C]` and the variable `startvalue` will have the value `A`. If the procedure is invoked by saying

    (proc [a b c] "x)

then `inlist` will have the value `[A B C]` and `startvalue` will have the value `X`.

After all the required and optional input can come a single rest input, represented by the following notation:

    [:inputname]

This is a rest input rather than an optional input because there is no default value expression. There can be at most one rest input. When the procedure is invoked, the value of this inputname will be a list containing all of the actual inputs provided that were not used for required or optional inputs. Example:

    to proc :in1 [:in2 "foo] [:in3 "baz] [:in4]

If this procedure is invoked by saying

    proc "x

then `in1` has the value `X`, `in2` has the value `FOO`, `in3` has the value `BAZ`, and `in4` has the value `[]` (the empty list). If it’s invoked by saying

    (proc "a "b "c "d "e)

then `in1` has the value `A`, `in2` has the value `B`, `in3` has the value `C`, and `in4` has the value `[D E]`.

The maximum number of inputs for a procedure is infinite if a rest input is given; otherwise, it is the number of required inputs plus the number of optional inputs.

The default number of inputs for a procedure, which is the number of inputs that it will accept if its invocation is not enclosed in parentheses, is ordinarily equal to the minimum number. If you want a different default number you can indicate that by putting the desired default number as the last thing on the `TO` line. example:

    to proc :in1 [:in2 "foo] [:in3] 3

This procedure has a minimum of one input, a default of three inputs, and an infinite maximum.

Logo responds to the `TO` command by entering procedure definition mode. The prompt character changes from `?` to `>` and whatever instructions you type become part of the definition until you type a line containing only the word `END`.

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### define

    DEFINE procname text

command. Defines a procedure with name procname and text text. If there is already a procedure with the same name, the new definition replaces the old one. The text input must be a list whose members are lists. The first member is a list of inputs; it looks like a `TO` line but without the word `TO`, without the procedure name, and without the colons before input names. In other words, the members of this first sublist are words for the names of required inputs and lists for the names of optional or rest inputs. The remaining sublists of the text input make up the body of the procedure, with one sublist for each instruction line of the body. (There is no `END` line in the text input.) It is an error to redefine a primitive procedure unless the variable `REDEFP` has the value `TRUE`.

See section redefp .

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### text

    TEXT procname

outputs the text of the procedure named procname in the form expected by `DEFINE`: a list of lists, the first of which describes the inputs to the procedure and the rest of which are the lines of its body. The text does not reflect formatting information used when the procedure was defined, such as continuation lines and extra spaces.

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### fulltext

    FULLTEXT procname

outputs a representation of the procedure procname in which formatting information is preserved. If the procedure was defined with `TO`, `EDIT`, or `LOAD`, then the output is a list of words. Each word represents one entire line of the definition in the form output by `READWORD`, including extra spaces and continuation lines. The last member of the output represents the `END` line. If the procedure was defined with `DEFINE`, then the output is a list of lists. If these lists are printed, one per line, the result will look like a definition using `TO`. Note: the output from `FULLTEXT` is not suitable for use as input to `DEFINE`!

See section to , edit , load , define .

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### copydef

    COPYDEF newname oldname

command. Makes newname a procedure identical to oldname. The latter may be a primitive. If newname was already defined, its previous definition is lost. If newname was already a primitive, the redefinition is not permitted unless the variable `REDEFP` has the value `TRUE`.

Note: dialects of Logo differ as to the order of inputs to `COPYDEF`. This dialect uses "`MAKE` order," not "`NAME` order."

See section redefp , save , po , pot .

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## 7.2 Variable Definition

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### make

    MAKE varname value

command. Assigns the value value to the variable named varname, which must be a word. Variable names are case-insensitive. If a variable with the same name already exists, the value of that variable is changed. If not, a new global variable is created.

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### name

    NAME value varname				(library procedure)

command. Same as `MAKE` but with the inputs in reverse order.

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### local

    LOCAL varname
    LOCAL varnamelist
    (LOCAL varname1 varname2 ...)

command. Accepts as inputs one or more words, or a list of words. A variable is created for each of these words, with that word as its name. The variables are local to the currently running procedure. Logo variables follow dynamic scope rules; a variable that is local to a procedure is available to any subprocedure invoked by that procedure. The variables created by `LOCAL` have no initial value; they must be assigned a value (e.g., with `MAKE`) before the procedure attempts to read their value.

See section make .

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### localmake

    LOCALMAKE varname value				(library procedure)

command. Makes the named variable local, like `LOCAL`, and assigns it the given value, like `MAKE`.

See section local , See section make .

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### thing

    THING varname
    :quoted.varname

outputs the value of the variable whose name is the input. If there is more than one such variable, the innermost local variable of that name is chosen. The colon notation is an abbreviation not for `THING` but for the combination

    thing "

so that `:FOO` means `THING "FOO`.

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### global

    GLOBAL varname
    GLOBAL varnamelist
    (GLOBAL varname1 varname2 ...)

command. Accepts as inputs one or more words, or a list of words. A global variable is created for each of these words, with that word as its name. The only reason this is necessary is that you might want to use the "setter" notation `SETXYZ` for a variable `XYZ` that does not already have a value; `GLOBAL "XYZ` makes that legal. Note: If there is currently a local variable of the same name, this command does *not* make Logo use the global value instead of the local one.

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## 7.3 Property Lists

Note: Names of property lists are always case-insensitive. Names of individual properties are case-sensitive or case-insensitive depending on the value of `CASEIGNOREDP`, which is `TRUE` by default.

See section caseignoredp .

In principle, every possible name is the name of a property list, which is initially empty. So Logo never gives a "no such property list" error, as it would for undefined procedure or variable names. But the primitive procedures that deal with "all" property lists (`CONTENTS`, `PLISTS`, etc.) list only nonempty ones. To "erase" a property list erase means to make it empty, removing all properties from it.

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### pprop

    PPROP plistname propname value

command. Adds a property to the plistname property list with name propname and value value.

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### gprop

    GPROP plistname propname

outputs the value of the propname property in the plistname property list, or the empty list if there is no such property.

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### remprop

    REMPROP plistname propname

command. Removes the property named propname from the property list named plistname.

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### plist

    PLIST plistname

outputs a list whose odd-numbered members are the names, and whose even-numbered members are the values, of the properties in the property list named plistname. The output is a copy of the actual property list; changing properties later will not magically change a list output earlier by `PLIST`.

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## 7.4 Workspace Predicates

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### procedurep

    PROCEDUREP name
    PROCEDURE? name

outputs `TRUE` if the input is the name of a procedure.

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### primitivep

    PRIMITIVEP name
    PRIMITIVE? name

outputs `TRUE` if the input is the name of a primitive procedure (one built into Logo). Note that some of the procedures described in this document are library procedures, not primitives.

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### definedp

    DEFINEDP name
    DEFINED? name

outputs `TRUE` if the input is the name of a user-defined procedure, including a library procedure.

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### namep

    NAMEP name
    NAME? name

outputs `TRUE` if the input is the name of a variable.

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### plistp

    PLISTP name
    PLIST? name

outputs `TRUE` if the input is the name of a nonempty property list. (In principle every word is the name of a property list; if you haven’t put any properties in it, `PLIST` of that name outputs an empty list, rather than giving an error message.)

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## 7.5 Workspace Queries

Note: All procedures whose input is indicated as contentslist will accept a single word (taken as a procedure name), a list of words (taken as names of procedures), or a list of three lists as described under the `CONTENTS` command above.

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### contents

    CONTENTS

outputs a "contents list," i.e., a list of three lists containing names of defined procedures, variables, and property lists respectively. This list includes all unburied named items in the workspace.

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### buried

    BURIED

outputs a contents list including all buried named items in the workspace.

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### traced

    TRACED

outputs a contents list including all traced named items in the workspace.

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### stepped

    STEPPED

outputs a contents list including all stepped named items in the workspace.

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### procedures

    PROCEDURES

outputs a list of the names of all unburied user-defined procedures in the workspace. Note that this is a list of names, not a contents list. (However, procedures that require a contents list as input will accept this list.)

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### primitives

    PRIMITIVES

outputs a list of the names of all primitive procedures in the workspace. Note that this is a list of names, not a contents list. (However, procedures that require a contents list as input will accept this list.)

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### names

    NAMES

outputs a contents list consisting of an empty list (indicating no procedure names) followed by a list of all unburied variable names in the workspace.

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### plists

    PLISTS

outputs a contents list consisting of two empty lists (indicating no procedures or variables) followed by a list of all unburied nonempty property lists in the workspace.

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### namelist

    NAMELIST varname				(library procedure)
    NAMELIST varnamelist

outputs a contents list consisting of an empty list followed by a list of the name or names given as input. This is useful in conjunction with workspace control procedures that require a contents list as input.

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### pllist

    PLLIST plname					(library procedure)
    PLLIST plnamelist

outputs a contents list consisting of two empty lists followed by a list of the name or names given as input. This is useful in conjunction with workspace control procedures that require a contents list as input.

See section contents .

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### arity

    ARITY procedurename

outputs a list of three numbers: the minimum, default, and maximum number of inputs for the procedure whose name is the input. It is an error if there is no such procedure. A maximum of -1 means that the number of inputs is unlimited.

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### nodes

    NODES

outputs a list of two numbers. The first represents the number of nodes of memory currently in use. The second shows the maximum number of nodes that have been in use at any time since the last invocation of `NODES`. (A node is a small block of computer memory as used by Logo. Each number uses one node. Each non-numeric word uses one node, plus some non-node memory for the characters in the word. Each array takes one node, plus some non-node memory, as well as the memory required by its elements. Each list requires one node per element, as well as the memory within the elements.) If you want to track the memory use of an algorithm, it is best if you invoke `GC` at the beginning of each iteration, since otherwise the maximum will include storage that is unused but not yet collected.

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## 7.6 Workspace Inspection

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### po

    PRINTOUT contentslist
    PO contentslist

command. Prints to the write stream the definitions of all procedures, variables, and property lists named in the input contents list.

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### poall

    POALL						(library procedure)

command. Prints all unburied definitions in the workspace. Abbreviates `PO CONTENTS`.

See section contents .

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### pops

    POPS						(library procedure)

command. Prints the definitions of all unburied procedures in the workspace. Abbreviates `PO PROCEDURES`.

See section po , procedures .

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### pons

    PONS						(library procedure)

command. Prints the definitions of all unburied variables in the workspace. Abbreviates `PO NAMES`.

See section po , names .

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### popls

    POPLS						(library procedure)

command. Prints the contents of all unburied nonempty property lists in the workspace. Abbreviates `PO PLISTS`.

See section po , plists .

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### pon

    PON varname					(library procedure)
    PON varnamelist

command. Prints the definitions of the named variable(s).
Abbreviates `PO NAMELIST varname(list)`.

See section po , namelist .

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### popl

    POPL plname					(library procedure)
    POPL plnamelist

command. Prints the definitions of the named property list(s).
Abbreviates `PO PLLIST plname(list)`.

See section po , pllist .

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### pot

    POT contentslist

command. Prints the title lines of the named procedures and the definitions of the named variables and property lists. For property lists, the entire list is shown on one line instead of as a series of `PPROP` instructions as in `PO`.

See section pprop , po .

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### pots

    POTS						(library procedure)

command. Prints the title lines of all unburied procedures in the workspace. Abbreviates `POT PROCEDURES`.

See section procedures .

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## 7.7 Workspace Control

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### erase

    ERASE contentslist
    ER contentslist

command. Erases from the workspace the procedures, variables, and property lists named in the input. Primitive procedures may not be erased unless the variable `REDEFP` has the value `TRUE`.

See section redefp .

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### erall

    ERALL

command. Erases all unburied procedures, variables, and property lists from the workspace. Abbreviates `ERASE CONTENTS`.

See section contents .

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### erps

    ERPS

command. Erases all unburied procedures from the workspace.
Abbreviates `ERASE PROCEDURES`.

See section erase , procedures .

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### erns

    ERNS

command. Erases all unburied variables from the workspace. Abbreviates `ERASE NAMES`.

See section erase , names .

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### erpls

    ERPLS

command. Erases all unburied property lists from the workspace.
Abbreviates `ERASE PLISTS`.

See section erase , plists .

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### ern

    ERN varname					(library procedure)
    ERN varnamelist

command. Erases from the workspace the variable(s) named in the input. Abbreviates `ERASE NAMELIST varname(list)`.

See section erase , namelist .

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### erpl

    ERPL plname					(library procedure)
    ERPL plnamelist

command. Erases from the workspace the property list(s) named in the input. Abbreviates `ERASE PLLIST plname(list)`.

See section erase , pllist .

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### bury

    BURY contentslist

command. Buries the procedures, variables, and property lists named in the input. A buried item is not included in the lists output by `CONTENTS`, `PROCEDURES`, `VARIABLES`, and `PLISTS`, but is included in the list output by `BURIED`. By implication, buried things are not printed by `POALL` or saved by `SAVE`.

See section contents , procedures , pons , plists , poall , save .

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### buryall

    BURYALL                                         (library procedure)

command. Abbreviates `BURY CONTENTS`.

See section contents .

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### buryname

    BURYNAME varname				(library procedure)
    BURYNAME varnamelist

command. Abbreviates `BURY NAMELIST `varname(list)``.

See section bury , namelist .

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### unbury

    UNBURY contentslist

command. Unburies the procedures, variables, and property lists named in the input. That is, the named items will be returned to view in `CONTENTS`, etc.

See section contents .

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### unburyall

    UNBURYALL					(library procedure)

command. Abbreviates `UNBURY BURIED`.

See section buried .

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### unburyname

    UNBURYNAME varname				(library procedure)
    UNBURYNAME varnamelist

command. Abbreviates `UNBURY NAMELIST varname(list)`.

See section unbury , namelist .

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### buriedp

    BURIEDP contentslist
    BURIED? contentslist

outputs `TRUE` if the first procedure, variable, or property list named in the contents list is buried, `FALSE` if not. Only the first thing in the list is tested; the most common use will be with a word as input, naming a procedure, but a contents list is allowed so that you can `BURIEDP [[] [variable]]` or `BURIEDP [[] [] [proplist]]`.

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### trace

    TRACE contentslist

command. Marks the named items for tracing. A message is printed whenever a traced procedure is invoked, giving the actual input values, and whenever a traced procedure `STOP`s or `OUTPUT`s. A message is printed whenever a new value is assigned to a traced variable using `MAKE`. A message is printed whenever a new property is given to a traced property list using `PPROP`.

See section stop , output , make , pprop .

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### untrace

    UNTRACE contentslist

command. Turns off tracing for the named items.

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### tracedp

    TRACEDP contentslist
    TRACED? contentslist

outputs `TRUE` if the first procedure, variable, or property list named in the contents list is traced, `FALSE` if not. Only the first thing in the list is tested; the most common use will be with a word as input, naming a procedure, but a contents list is allowed so that you can `TRACEDP [[] [variable]]` or `TRACEDP [[] [] [proplist]]`.

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### step

    STEP contentslist

command. Marks the named items for stepping. Whenever a stepped procedure is invoked, each instruction line in the procedure body is printed before being executed, and Logo waits for the user to type a newline at the terminal. A message is printed whenever a stepped variable name is shadowed because a local variable of the same name is created either as a procedure input or by the `LOCAL` command.

See section local .

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### unstep

    UNSTEP contentslist

command. Turns off stepping for the named items.

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### steppedp

    STEPPEDP contentslist
    STEPPED? contentslist

outputs `TRUE` if the first procedure, variable, or property list named in the contents list is stepped, `FALSE` if not. Only the first thing in the list is tested; the most common use will be with a word as input, naming a procedure, but a contents list is allowed so that you can `STEPPEDP [[] [variable]]` or `STEPPEDP [[] [] [proplist]]`.

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### edit

    EDIT contentslist
    ED contentslist
    (EDIT)
    (ED)

command. If invoked with an input, `EDIT` writes the definitions of the named items into a temporary file and edits that file, using an editor that depends on the platform you’re using. In wxWidgets, and in the MacOS Classic version, there is an editor built into Logo. In the non-wxWidgets versions for Unix, MacOS X, Windows, and DOS, Logo uses your favorite editor as determined by the `EDITOR` environment variable. If you don’t have an `EDITOR` variable, edits the definitions using `jove`. If invoked without an input, `EDIT` edits the same file left over from a previous `EDIT` or `EDITFILE` instruction. When you leave the editor, Logo reads the revised definitions and modifies the workspace accordingly. It is not an error if the input includes names for which there is no previous definition.

If there is a variable `LOADNOISILY` whose value is `TRUE`, then, after leaving the editor, `TO` commands in the temporary file print ‘`procname defined`’ (where procname is the name of the procedure being defined); if `LOADNOISILY` is `FALSE` or undefined, `TO` commands in the file are carried out silently.

If there is an environment variable called `TEMP`, then Logo uses its value as the directory in which to write the temporary file used for editing.

Exceptionally, the `EDIT` command can be used without its default input and without parentheses provided that nothing follows it on the instruction line.

See section loadnoisily , See section editfile .

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### editfile

    EDITFILE filename

command. Starts the Logo editor, like `EDIT`, but instead of editing a temporary file it edits the file specified by the input. When you leave the editor, Logo reads the revised file, as for `EDIT`. `EDITFILE` also remembers the filename, so that a subsequent `EDIT` command with no input will re-edit the same file.

`EDITFILE` is intended as an alternative to `LOAD` and `SAVE`. You can maintain a workspace file yourself, controlling the order in which definitions appear, maintaining comments in the file, and so on.

In the wxWidgets version, `EDITFILE` asks whether or not you want to load the file into Logo when you finish editing. This allows you to use `EDITFILE` to edit data files without leaving Logo.

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### edall

    EDALL						(library procedure)

command. Abbreviates `EDIT CONTENTS`.

See section contents .

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### edps

    EDPS						(library procedure)

command. Abbreviates `EDIT PROCEDURES`.

See section edit , procedures .

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### edns

    EDNS						(library procedure)

command. Abbreviates `EDIT NAMES`.

See section edit , names .

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### edpls

    EDPLS						(library procedure)

command. Abbreviates `EDIT PLISTS`.

See section edit , plists .

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### edn

    EDN varname					(library procedure)
    EDN varnamelist

command. Abbreviates `EDIT NAMELIST varname(list)`.

See section edit , namelist .

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### edpl

    EDPL plname					(library procedure)
    EDPL plnamelist

command. Abbreviates `EDIT PLLIST plname(list)`.

See section edit , pllist .

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### save

    SAVE filename

command. Saves the definitions of all unburied procedures, variables, and nonempty property lists in the named file. Equivalent to

    to save :filename
    local "oldwriter
    make "oldwriter writer
    openwrite :filename
    setwrite :filename
    poall
    setwrite :oldwriter
    close :filename
    end

Exceptionally, `SAVE` can be used with no input and without parentheses if it is the last thing on the command line. In this case, the filename from the most recent `LOAD` or `SAVE` command will be used. (It is an error if there has been no previous `LOAD` or `SAVE`.)

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### savel

    SAVEL contentslist filename			(library procedure)

command. Saves the definitions of the procedures, variables, and property lists specified by contentslist to the file named filename.

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### load

    LOAD filename

command. Reads instructions from the named file and executes them. The file can include procedure definitions with `TO`, and these are accepted even if a procedure by the same name already exists. If the file assigns a list value to a variable named `STARTUP`, then that list is run as an instructionlist after the file is loaded. If there is a variable `LOADNOISILY` whose value is `TRUE`, then `TO` commands in the file print ‘`procname defined`’ (where procname is the name of the procedure being defined); if `LOADNOISILY` is `FALSE` or undefined, `TO` commands in the file are carried out silently.

See section startup , See section loadnoisily .

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### cslsload

    CSLSLOAD name

command. Loads the named file, like `LOAD`, but from the directory containing the Computer Science Logo Style programs instead of the current user’s directory.

See section load .

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### help

    HELP name
    (HELP)

command. Prints information from the reference manual about the primitive procedure named by the input. With no input, lists all the primitives about which help is available. If there is an environment variable `LOGOHELP`, then its value is taken as the directory in which to look for help files, instead of the default help directory.

If `HELP` is called with the name of a defined procedure for which there is no help file, it will print the title line of the procedure followed by lines from the procedure body that start with semicolon, stopping when a non-semicolon line is seen.

Exceptionally, the `HELP` command can be used without its default input and without parentheses provided that nothing follows it on the instruction line.

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### seteditor

    SETEDITOR path

command. Tells Logo to use the specified program as its editor instead of the default editor. The format of a path depends on your operating system.

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### setlibloc

    SETLIBLOC path

command. Tells Logo to use the specified directory as its library instead of the default. (Note that many Logo "primitive" procedures are actually found in the library, so they may become unavailable if your new library does not include them!) The format of a path depends on your operating system.

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### setcslsloc

    SETCSLSLOC path

command. Tells Logo to use the specified directory for the `CSLSLOAD` command, instead of the default directory. The format of a path depends on your operating system.

See section cslsload .

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### sethelploc

    SETHELPLOC path

command. Tells Logo to look in the specified directory for the information provided by the HELP command, instead of the default directory. The format of a path depends on your operating system.

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### settemploc

    SETTEMPLOC path

command. Tells Logo to write editor temporary files in the specified directory rather than in the default directory. You must have write permission for this directory. The format of a path depends on your operating system.

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### gc

    GC
    (GC anything)

command. Runs the garbage collector, reclaiming unused nodes. Logo does this when necessary anyway, but you may want to use this command to control exactly when Logo does it. In particular, the numbers output by the `NODES` operation will not be very meaningful unless garbage has been collected. Another reason to use `GC` is that a garbage collection takes a noticeable fraction of a second, and you may want to schedule collections for times before or after some time-critical animation. If invoked with an argument (of any value), `GC` runs a full garbage collection, including GCTWA (Garbage Collect Truly Worthless Atoms, which means that it removes from Logo’s memory words that used to be procedure or variable names but aren’t any more); without an argument, `GC` does a generational garbage collection, which means that only recently created nodes are examined. (The latter is usually good enough.)

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### .setsegmentsize

    .SETSEGMENTSIZE num

command. Sets the number of nodes that Logo allocates from the operating system at once to num, which must be a positive integer. The name is dotted because bad things will happen if you use a number that’s too small or too large for your computer. The initial value is 16,000 for most systems, but is smaller for 68000-based Macs. Making it larger will speed up computations (by reducing the number of garbage collections) at the cost of allocating more memory than necessary.

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