[McJones] History of John Backus's functional programming project
pointfree interpreter with instance variables and classes, in lazarus
Function-level Programming like FP from John Backus
ip ≡ (+ \) ° (* aa) ° trans ° ee
eq0 ≡ id=0
sub1 ≡ id-1
fact ≡ eq0 → 1; id*fact°sub1
for example: generation of numbers with iota
iota == [1]°((ispos°[0])->*(pred°[0]),([0],[1]),)°id,(),
iota ° 10
--> (1 ; 2 ; 3 ; 4 ; 5 ; 6 ; 7 ; 8 ; 9 ; 10 ;)
possibility to work with tables/instance-variables like in trivia
(#beta & #alpha & #gamma & #delta & "US") ° (delta:="K") ° '("A" alpha "B" beta "C" gamma)
--> "BACKUS"
defining classes and using objects
constr == .. { object
[head] == head ° pop
[tail] == tail dip
[comma] == (top°[0]) obj [1],pop°[0]
[reverse] == reverse dip // method
}
--> ( )
reverse ° (constr :: A;B;C;) // reverse == [reverse] fn ...
--> (constr :: C ; B ; A ;)
side-effects used in installer.exe
((#draco loadtext)°(draco:=corepath & "drache.pf") eff 'io)>>(it showinfo)>>(#draco run)>>()
meta-programming: you can also create your own combining forms like in Backus FFP
quoteit == top°term
(a quoteit)
--> a
twice == (top°term) app (top°term) app arg
((id+1) twice) ° 5
--> 7
while == ((top°term) app arg)->(term app (pop°term) app arg);arg
head°((isprop°tail) while tail) ° (a;b;c;d;e;)
--> e
WHERE Clause with Instance Variables
sumtrisqinc == ( #sum app (([1] app [0]) aa0)
° (#co app #inc app it) ee #square )
where ( sum == + \
co == id,id,id,
square == id*id
inc == id+1 )
sumtrisqinc°10
--> 363
Duplicate definitions with identical code are not flagged as errors.
Limited API support: httpget and parsejson for reading APIs. (Version-20240701)
Example
Reference.pdf
Quickinfo.pdf
Website
Getting Startet ...
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If you like pointfrip you can download and use it.
Can you write any function in point-free notation?
This is a Red language: Closed applicative languages