HE vs ML discrepancy: weird semantic differences "+" and numbers: "+2" as "2" vs "uninterpreted symbol, vanishing results using + on "A", treating (2) the same as 2.

[zariuq]

Semantics of "+2":

• HE interprets this as "positive two" whereas ML considers it "+2" as an uninterpreted symbol.

Hyperon Experimental (HE) via metta-repl

> !(+ 2 3)
[5]
> !(+2 3)
[(2 3)]

MeTTaLog (ML) via mettalog --repl

metta+>!(+ 2 3)
[5]

metta+>!(+2 3)
[(+2 3)]

Semantics of + assigned to non-numerals

• ML eats the result when it should leave the result untouched (or, apparently, reduce the +2).

HE:

> !(+ +2 A)
[(+ 2 A)]

MeTTaLog:

metta+>!(+ 2 A)
;; no-results ;; 
[]

Semantics of evaluating (2)

• ML treats (2) and (3) like 2 and 3.

HE:

> !(== 2 (2))
[False]

ML:

metta+>!(== 2 (2))
[True]

HE:

> !(+ (2) (3))
[(+ (2) (3))]

> !(+ ((2)) ((3)))
[(+ ((2)) ((3)))]

ML:

metta+>!(+ (2) (3))
[5]

metta+>!(+ ((2)) ((3)))
[(+ ((2)) ((3)))]