Implementation Comparisons

Features Missing in NARS2000

• Selective Assignment: The syntax of (...)←... where the code inside of the parens selects elements of a named array is missing from NARS2000. It may be emulated by using Indexed Assignment:

  Dyalog:	((⊂ L)⌷R)←...
  NARS2000:	R[L]←...

Differences With Dyalog APL

Different designers make different choices. Neither should be considered Good or Bad, just different. Here are a few of the differences between Dyalog APL and NARS2000:

• Multi-name assignment in Dyalog does not require parens, whereas NARS2000 does
  

  Dyalog:	i j ←⍺
  NARS2000:	(i j)←⍺

• A Train assigned to a name does not require parens in Dyalog, but are required in NARS2000
  

  Dyalog:	e← -phi grad
  NARS2000:	e←(-phi grad)

• Dyalog's definition of the monadic function ↑ depends upon the value of ⎕ML (⎕ML<2 is Mix, ⎕ML≥2 is First), whereas NARS2000 uses the monadic function ⊃ for Mix and ↑ for First
  

  Dyalog:	csc←{sign↑⍳n⍴n←⍴⍵}
  NARS2000:	csc←{sign⊃⍳n⍴n←⍴⍵}

• I'm not sure about Dyalog, but I know that NARS2000 does not have the concept of Rank well-integrated into its implementation.
• The Binding Strength Rules are different. In NARS2000, a numeric strand as the right operand to an operator must be enclosed in parens
  

  Dyalog:	⍤ 0 1
  NARS2000:	⍤(0 1)