Migration level (⎕ML, )EvLevel, ⎕CS), Evolution level, or Compatibility setting is a number that, in Dyalog APL, APL+Win, and APLX respectively, specifies exact behaviour relative to APL2. In Dyalog APL and APL+Win, a lower value represents a behaviour closer to the original NARS specification, while a higher the value represents a behaviour closer to APL2. In APLX, a lower value matches APL2 while a higher value indicates higher backwards compatibility with APL.68000.
APL+Win settings
Work-arounds
APL+Win provides system function alternatives to the functions that are affected by moving to evolution level 2:
Dyalog settings
Dyalog APL currently offers the following settings:
⎕ML=0
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Z←∊R
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Monadic ∊ is interpreted as Type rather than Enlist.
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⎕ML=1
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Default behaviour
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⎕ML≥2
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Z←↑R
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Monadic ↑ is interpreted as First rather than Mix.
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Z←⊃R
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Monadic ⊃ is interpreted as Mix rather than First.
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Z←≡R
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Monadic ≡ returns a positive rather than a negative value, if its argument has non-uniform depth.
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⎕ML=3
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R←X⊂[K]Y
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Dyadic ⊂ is interpreted as Partition (⊆) rather than Partitioned Enclose.
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⎕TC
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The order of the elements of ⎕TC is the same as in APL2.
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Work-arounds
When migrating to Dyalog APL, the below drop-ins for the affected built-ins allow setting ⎕ML←1 while preserving code behaviour. It is then safe to programmatically (as shown in the rightmost column) change all occurrences of the affected built-ins with their respective covers.
| Migrating from |
Define |
Then run this on all code
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⎕ML=0
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Epsilon←{×⎕NC'⍺':⍺∊⍵ ⋄ ⊃0⍴⊂⍵}
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'''[^'']+''' '∊'⎕R'&' 'Epsilon'
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⎕ML=2
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UpArrow←{×⎕NC'⍺':⍺↑⍵ ⋄ ⊃⍵}
RightShoe←{×⎕NC'⍺':⍺↑⍵ ⋄ ↑⍵}
EqualUnderbar←|≡
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'''[^'']+''' '↑' '⊃' '≡'⎕R'&' 'UpArrow' 'RightShoe' 'EqualUnderbar'
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⎕ML=3
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UpArrow←{×⎕NC'⍺':⍺↑⍵ ⋄ ⊃⍵}
RightShoe←{×⎕NC'⍺':⍺↑⍵ ⋄ ↑⍵}
EqualUnderbar←(|≡)
LeftShoe←{×⎕NC'⍺':⍺⊆⍵ ⋄ ⊂⍵}
quadTC←(⎕UCS 8 13 10)
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'''[^'']+''' '↑' '⊃' '≡' '⊂' '⎕TC'⎕R'&' 'UpArrow' 'RightShoe' 'EqualUnderbar' 'LeftShoe' ' quadTC'
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Alternatively, the definitions can be used directly inside the text substitutions, whereby one avoids polluting existing code with these cover names.
APLX settings
APLX treats the value as a collection of individual bits, thus allowing the combination of an exact set of behaviours:
⎕CS←1 |
Stranding is done before bracket indexing
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⎕CS←2 |
The name class of an invalid name is 4 rather than ¯1.
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⎕CS←4 |
Format (⍕) and default output uses the same width for all columns, rather than determining the width separately for each column.
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External links
Documentation
| APL built-ins [edit]
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| Primitives (Timeline) |
Functions
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| Scalar
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| Monadic
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Conjugate ∙ Negate ∙ Signum ∙ Reciprocal ∙ Magnitude ∙ Exponential ∙ Natural Logarithm ∙ Floor ∙ Ceiling ∙ Factorial ∙ Not ∙ Pi Times ∙ Roll ∙ Type ∙ Imaginary ∙ Square Root ∙ Round
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| Dyadic
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Add ∙ Subtract ∙ Times ∙ Divide ∙ Residue ∙ Power ∙ Logarithm ∙ Minimum ∙ Maximum ∙ Binomial ∙ Comparison functions ∙ Boolean functions (And, Or, Nand, Nor) ∙ GCD ∙ LCM ∙ Circular ∙ Complex ∙ Root
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| Non-Scalar
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| Structural
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Shape ∙ Reshape ∙ Tally ∙ Depth ∙ Ravel ∙ Enlist ∙ Table ∙ Catenate ∙ Reverse ∙ Rotate ∙ Transpose ∙ Raze ∙ Mix ∙ Split ∙ Enclose ∙ Nest ∙ Cut (K) ∙ Pair ∙ Link ∙ Partitioned Enclose ∙ Partition
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| Selection
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First ∙ Pick ∙ Take ∙ Drop ∙ Unique ∙ Identity ∙ Stop ∙ Select ∙ Replicate ∙ Expand ∙ Set functions (Intersection ∙ Union ∙ Without) ∙ Bracket indexing ∙ Index ∙ Cartesian Product ∙ Sort
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| Selector
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Index generator ∙ Grade ∙ Index Of ∙ Interval Index ∙ Indices ∙ Deal ∙ Prefix and suffix vectors
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| Computational
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Match ∙ Not Match ∙ Membership ∙ Find ∙ Nub Sieve ∙ Encode ∙ Decode ∙ Matrix Inverse ∙ Matrix Divide ∙ Format ∙ Execute ∙ Materialise ∙ Range
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| Operators |
Monadic
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Each ∙ Commute ∙ Constant ∙ Replicate ∙ Expand ∙ Reduce ∙ Windowed Reduce ∙ Scan ∙ Outer Product ∙ Key ∙ I-Beam ∙ Spawn ∙ Function axis ∙ Identity (Null, Ident)
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| Dyadic
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Bind ∙ Compositions (Compose, Reverse Compose, Beside, Withe, Atop, Over) ∙ Inner Product ∙ Determinant ∙ Power ∙ At ∙ Under ∙ Rank ∙ Depth ∙ Variant ∙ Stencil ∙ Cut ∙ Direct definition (operator) ∙ Identity (Lev, Dex)
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| Quad names
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Index origin ∙ Comparison tolerance ∙ Migration level ∙ Atomic vector
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