LYaPAS

Logical Language for the Representation of Synthesis Algorithms, or LYaPAS (ЛЯПАС), is a programming language that sprung out of 1964 Soviet Russia. Extending from APL, it is based on set-theoretical considerations oriented toward the programming of synthesis algorithms for finite-state and discrete devices. The language is self-extending and self-compiling with only a minimal translator written for the native machine environment.

Speciality keyboard mappings are highly recommended for entering in the many non-typical keyboard symbols found in the language.

Its use of octal numbers within the language specification is considered one of its interesting qualities.

LYaPAS-M is a further refinement of LYaPAS.

l-operators
First-level operators in the language.

Implicit Variable τ
Implicit variable τ is a symbol that never appears in the program. The current value of τ is the result of the the realization of the current operator.

L-operators
Second-level operators in the language.

Example
genadj. Perform generalized adjunction (joining) of intervals of a set.

genadj ακ?, ßκ? /b, d/ (αß)

170 233 4 (αab)

○ a ⇒ bbα ⇒ dc0 ┐⇒ b

Test for generalized adjunction of intervals Ia and Ib, formation of the interval Id—the result of the generalized adjunction—and setting of tags:

§1 △ a ⊕ d ○ → 4αa ⊕ αb∧ b ⇒ aßa ⊕ ßb ∧ a ⇒ a ⇤ ⊕ c0 ↦ 1αa ∨ αb ⊕ a ⇒ αd?ßα ∧ ßb ∨ a ∨ c0 ⇒ ßd?c0 ∨ αa ⇒ αac0 ∨ αb ⇒ αb ○ c ○ a

Test for presence of interval Id in Int:

§2 αc ⊕ αd ⊕ b |→ 3ßc ⊕ ßd ∧ b ↦ 3c0 ∨ ßc ⇒ ßc ○̄ a

§3 △ c ⊕ d ↦ 2a ↦ 1 △ d → 1

§4 ○̄ a △ b ⊕ d ↦ 1d ⇒ bα ⇒ bß

External resources

 * LYaPAS in the Encyclopedia of Programming Languages
 * Library of Congress entry for LYaPAS: a programming language for logic and coding algorithms