I-Beam

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⌶

I-Beam (⌶) is a primitive monadic operator that takes a numeric code as it's operand and derives an ambivalent function which provides a range of ad-hoc operations. This range covers non-primitive functions - for example: experimental features, interpreter-level control, access to the environment, and information about APL itself.

History

I-Beam was introduced in APL\360 by implementers to execute System/360 instructions from program control. The convenience of this lead to I-Beam becoming directly available to use by anyone.[1]

Mnemonics

In general, I-Beam's numeric operand isn't intended to be easily recalled. But some are given meaningful names.

One method is to devise a name from the Roman numeral letters I, V, X, L, C, D, and M[2]

I-Beam Numeral
Called Monadically CM (900)
Line Count LC (50100)

References

  1. ↑ The Design of APL
  2. ↑ I-Beam Mnemonics
APL built-ins [edit]
Primitive functions
Scalar
Monadic Conjugate ∙ Negate ∙ Signum ∙ Reciprocal ∙ Magnitude ∙ Exponential ∙ Natural Logarithm ∙ Floor ∙ Ceiling ∙ Factorial ∙ Not ∙ Pi Times ∙ Roll ∙ Type ∙ Imaginary ∙ Square Root
Dyadic Add ∙ Subtract ∙ Times ∙ Divide ∙ Residue ∙ Power ∙ Logarithm ∙ Minimum ∙ Maximum ∙ Binomial ∙ Comparison functions ∙ Boolean functions (And, Or, Nand, Nor) ∙ GCD ∙ LCM ∙ Circular ∙ Complex ∙ Root
Non-Scalar
Structural Shape ∙ Reshape ∙ Tally ∙ Depth ∙ Ravel ∙ Enlist ∙ Table ∙ Catenate ∙ Reverse ∙ Rotate ∙ Transpose ∙ Raze ∙ Mix ∙ Split ∙ Enclose ∙ Nest ∙ Cut (K) ∙ Pair ∙ Link ∙ Partitioned Enclose ∙ Partition
Selection First ∙ Pick ∙ Take ∙ Drop ∙ Unique ∙ Identity ∙ Select ∙ Replicate ∙ Expand ∙ Set functions (Intersection ∙ Union ∙ Without) ∙ Bracket indexing ∙ Index
Selector Index generator ∙ Grade ∙ Index Of ∙ Interval Index ∙ Indices ∙ Deal
Computational Match ∙ Not Match ∙ Membership ∙ Find ∙ Nub Sieve ∙ Encode ∙ Decode ∙ Matrix Inverse ∙ Matrix Divide ∙ Format ∙ Execute ∙ Materialise ∙ Range
Primitive operators Monadic Each ∙ Commute ∙ Constant ∙ Replicate ∙ Expand ∙ Reduce ∙ Windowed Reduce ∙ Scan ∙ Outer Product ∙ Key ∙ I-Beam ∙ Spawn ∙ Function axis
Dyadic Bind ∙ Compositions (Compose, Reverse Compose, Beside, Withe, Atop, Over) ∙ Inner Product ∙ Power ∙ At ∙ Under ∙ Rank ∙ Depth ∙ Variant ∙ Stencil ∙ Cut (J)
Quad names
Arrays Index origin ∙ Migration level ∙ Atomic vector
Functions Name class ∙ Case convert ∙ Unicode convert
Operators Search ∙ Replace
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