Language Features

At the moment, the following sections describe only those language features that are New or Enhanced relative to the Extended APL Standard, or that deserve special comment.

Syntax

• Strand Assignment: (A₁ A₂ ... A_n)←R
• Modify Assignment: Af←R
• Modify Strand Assignment: (A₁ A₂ ... A_n)f←R
• Function/Operator Assignment: A←f,   A←op1,   A←op2
• Sink: ←R
• Point Notation:
  • Base — 16b10FFFF as a shorthand for 16⊥1 0 15 15 15 15
  • Pi — 2p3 as a shorthand for 2π³ or 2×(○1)*3
  • Euler — 2x3 as a shorthand for 2e³ or 2×(*1)*3.
• Trains: e.g., avg←(+⌿ ÷ ≢) applies the functions to its argument(s) in a particular way (in this case, to compute the average of a numeric scalar or vector).
• System Labels: ⎕PRO and ⎕ID in user-defined functions/operators.
• Anonymous Functions/Operators: one-line grouping of one or more statements all enclosed in braces such as {(+⌿⍵)÷≢⍵}.

Primitive functions

• Array Lookup: L⍸R
• Find: L⍷R
• Index Generator: ⍳R
• Index Of: L⍳R
• Indexing: R[L],   R[L]←A,   R[L]f←A,   L⌷R,   L⍉R,    L⊃R
• Indices: ⍸R
• Matrix Inverse/Divide: ⌹R,   L⌹R
• Mismatch: L≢R
• Partitioned Enclose: L⊂[X] R
• Primes: πR and LπR
• Reshape: L⍴R
• Root: √R and L√R
• Sequence: L..R
• Tally: ≢R
• Without: L~R

Primitive operators

• Axis: f[X], f op1[X], f op2[X]g
• Composition: f⍥g
• Compose: f∘g,   f∘R,   L∘g
• Multisets: f⍦
• Null: f⊙
• Rank: f⍤[X] Y
• Variant: f⍠V

Datatypes

• Infinity: ∞ and ¯∞
• Arithmetic Progression Arrays: 2 3 4⍴⍳24
• Unicode Characters
• Array Predicates
• Rational Numbers: 1r3 and 12345x
• Variable-precision Floating Point (VFP) Numbers: 1.234v and 12v

System Commands

System Commands provide features to the user of the APL system, separate from actual workspaces, variables or APL operators. These provide such features as accessing files, saving a workspace, and exiting the APL interpreter. The commands are not case sensitive, so )IN and )in do the same thing.

NARS2000 currently has the following system commands:

)BOX Turn ON/OFF box around output )CLEAR Start a new session manager window with an empty workspace )CLOSE )COPY )DROP )EDIT Create a new function in the workspace or edit an existing function )ERASE Delete a variable or function in the current workspace )EXIT Close down the interpreter and exit the program. Same as )OFF )FNS )FOP Display functions, operators, and hyperators. Same as )FOPS )FOPS )HYP Display hyperators only )IN )INASCII     )LIB )LAOD Alternative spelling of )LOAD )LOAD Load an existing workspace )NEWTAB

)NMS )OFF Close down the interpreter and exit the program. Same as )EXIT )OPEN )OPS Display operators only )OUT )RESET )SAVE Save the current workspace )SVAE Alternative spelling for )SAVE )SI workspace State Indicator )SIC State Indicator Clear )SINL )SYMB )ULIB )VARS )XLOAD )WSID

System Variables

System Variables
⎕ALX	Attention Latent Expression
⎕CT	Comparison Tolerance
⎕DM	Diagnostic Message (Read-only)
⎕DT	Distribution Type
⎕ELX	Error Latent Expression
⎕FC	Format Control
⎕FEATURE	Feature Control
⎕FPC	Floating Point Control
⎕IC	Indeterminate Control
⎕IO	Index Origin
⎕LR	Left-Right Direction Choice
⎕LX	Latent Expression
⎕PP	Print Precision
⎕PR	Prompt Replacement
⎕PW	Print Width
⎕RL	Random Link
⎕SA	Stop Action
⎕WSID	Workspace Identifier

System Functions

Niladic System Functions
⎕A	The alphabet from A to Z, also Á to Ź,  to Ẑ, À to À, Ä to Z and à to Z, all in lowercase, too using the variations ⎕a ⎕A ⎕á ⎕Á ⎕à ⎕À ⎕â ⎕ ⎕ä ⎕Ä ⎕ã ⎕Ã
⎕AV	Atomic Vector
⎕CS	Collating sequence
⎕EM	Event Message
⎕ET	Event Type
⎕LC	Line Counter
⎕NNAMES	Names of Open Native Files
⎕NNUMS	Tie Numbers of Open Native Files
⎕SI	State Indicator
⎕SYSID	System Identifier
⎕SYSVER	System Version
⎕T	Tickcount
⎕TC	Terminal Control Characters
⎕TCBEL	Terminal Control Character, Bell
⎕TCBS	Terminal Control Character, Backspace
⎕TCESC	Terminal Control Character, Escape
⎕TCFF	Terminal Control Character, Form Feed
⎕TCHT	Terminal Control Character, Horizontal Tab
⎕TCLF	Terminal Control Character, Line Feed
⎕TCNL	Terminal Control Character, New Line
⎕TCNUL	Terminal Control Character, Null
⎕TS	Time Stamp
⎕WA	Workspace Available
Monadic or dyadic system functions
⎕AT	Attributes
⎕CR	Canonical representation
⎕DC	Data Conversion
⎕DFT	Discrete Fourier Transform
⎕DL	Delay or pause APL processing
⎕DR	Data representation
⎕EA	Execute alternate
⎕EC	Execute controlled
⎕ERROR	Signal error
⎕ES	Event simulate
⎕EX	Expunge names
⎕FMT	Format
⎕FX	Function fix
⎕MF	Monitor function
⎕NAPPEND	Append data to an open native file
⎕NC	Name classification
⎕NCREATE	Create and open a native file
⎕NERASE	Erase an open native file
⎕NINFO	Native file information
⎕NL	Name list
⎕NREAD	Read data from an open native file
⎕NRENAME	Rename an open native file
⎕NREPLACE	Replace data in an open native file
⎕NRESIZE	Resize an open native file
⎕NSIZE	Get the size of an open native file
⎕NTIE	Open a native file
⎕NUNTIE	Close a native file
⎕STOP	Stop execution of a user-defined function/operator/hyperator or Magic Function
⎕TF	Transfer form
⎕TRACE	Trace execution of a user-defined function/operator/hyperator or Magic Function
⎕UCS	Universal character set
⎕VR	Vector representation of a function