Language Features

From NARS2000

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.

Contents 1 Syntax 2 Primitive functions 3 Primitive operators 4 Datatypes 5 System Functions 6 System Variables

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 vector).
• System Labels: ⎕PROTOTYPE and ⎕IDENTITY in user-defined functions/operators.

Primitive functions

• Index Generator: ⍳R
• Index Of: L⍳R
• Indexing: R[L],   R[L]←A,   R[L]f←A,   L⌷R,   L⍉R    L⊃R
• Matrix Inverse/Divide: ⌹R,   L⌹R
• Without: L~R
• Partitioned Enclose: L⊂R
• Find: L⍷R

Primitive operators

• Axis: f[X], f op1[X], f op2[X]g
• Composition: f∘g,   f∘R,   L∘g
• Null: f⊙
• Rank: f⍤[X] Y

Datatypes

• Infinity: ∞ and ¯∞
• Arithmetic Progression Arrays: 2 3 4⍴⍳24
• Unicode Characters
• Array Predicates

System Functions

• ⎕A (Uppercase English Alphabet)
• ⎕AT (Object Attributes)
• ⎕AV (Atomic Vector)
• ⎕CR (Canonical Representation)
• ⎕DM (Diagnostic Message)
• ⎕DR (Data Representation)
• ⎕ERROR (Signal Error)
• ⎕FMT (Format)
• ⎕MF (Monitor Function)
• ⎕NC (Name Class)
• ⎕NL (Name List)
• ⎕SIZE (Object Size)
• ⎕SYSID (System Identifier)
• ⎕SYSVER (System Version)
• ⎕TC/⎕TCxxx (Terminal Control)
• ⎕TF (Transfer Form)
• ⎕TYPE (Object Prototype)
• ⎕UCS (Universal Character Set)
• ⎕VR (Visual Representation)
• ⎕WA (Workspace Available)

System Variables

• Scalar System Variables (⎕CT,   ⎕IO,   ⎕PP,   ⎕PW,   ⎕RL)
• ⎕ELX (Error Trapping)
• ⎕FC (Format Control)
• ⎕IC (Indeterminate Control)