Cliff Click Language Hacking
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cliffclick Rename TypeStruct args->flds
Big comments about doing recursive meets
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Cliff Click Language Hacking

To-the-metal performance: every abstraction used can be peeled away, yielding code that you would expect from a tightly written low-level program. This is a primary driver for me, the guy who's been writing compilers for high performance computing (including Java) all my life.

Modern: Statically typed. Functional programming with full H-M strength type inference. Minimal syntax. REPL (i.e. incremental static typing) and seperate compilation. Typed C-style macros: most syntax errors in dead code are typed.

My intent is a modern language that can be used where C or C++ is used: low-level high-performance work and a systems implementation language (e.g. OS's, device drivers, GC's), but bring in all the goodness of the last 20 years of language improvements.

I specifically intend to look at real-time constraints and the notion of Time in a language.

Part of modern coding is the use Garbage Collection and the structured use of malloc/free - so I intend to add Rust-style memory management.

Part of modern coding is the use of multiple cores, so I intend to explore a couple of different concurrency models.

And of course, this is a Work-In-Progress!!!!


BNF Comment
prog = stmts END
stmts= stmt [; stmt]*[;]? multiple statments; final ';' is optional
stmt = [id[:type]? =]* ifex ids must not exist, and are available in later statements
stmt = tvar = :type type variable assignment
ifex = expr ? expr : expr trinary logic
expr = term [binop term]* gather all the binops and sort by prec
term = tfact [tuple or fact or .field]* function application (includes uniop) or field lookup
tfact= fact[:type] Optionally typed fact
fact = id variable lookup
fact = num number
fact = "string" string
fact = (stmts) General statements parsed recursively
fact = tuple Tuple builder
fact = func Anonymous function declaration
fact = @{ [id[:type]?[=stmt]?,]* } Anonymous struct declaration; optional type, optional initial value, optional final comma
fact = {binop} Special syntactic form of binop; no spaces allowed; returns function constant
fact = {uniop} Special syntactic form of uniop; no spaces allowed; returns function constant
tuple= (stmts,[stmts,]) Tuple; final comma is optional
binop= +-*%&/<>!= etc; primitive lookup; can determine infix binop at parse-time, also pipe but GFM screws up
uniop= -!~ etc; primitive lookup; can determine infix uniop at parse-time
func = { [[id[:type]*]* ->]? stmts} Anonymous function declaration
str = [.\%]* String contents; \t\n\r% standard escapes
str = %[num]?[.num]?fact Percent escape embeds a 'fact' in a string; "name=%name\n"
type = tcon OR tfun OR tstruct OR ttuple OR tvar Types are a tcon or a tfun or a tstruct or a ttuple or a type variable
tcon = int, int[1,8,16,32,64], flt, flt[32,64], real, str Primitive types
tfun = {[[type]* ->]? type } Function types mirror func decls
ttuple = ( [:type]?,* ) Tuple types are just a list of optional types; the count of commas dictates the length, zero commas is zero length
tstruct = @{ [id[:type],]*} Struct types are field names with optional types


Code Comment
1 1:int
Prefix unary operator ---
-1 -1:int application of unary minus to a positive 1
!1 0:int convert 'truthy' to false
Infix binary operator ---
1+2 3:int
1-2 -1:int
1<=2 1:int Truth === 1
1>=2 0:int False === 0
Binary operators have precedence ---
1+2*3 7:int standard precedence
1+2 * 3+4 *5 27:int
(1+2)*(3+4)*5 105:int parens overrides precedence
1// some comment
3:int with bad comment
1 < 2 1:int true is 1, 1 is true
1 > 2 0:int false is 0, 0 is false
Float ---
1.2+3.4 4.6:flt
1+2.3 3.3:flt standard auto-widening of int to flt
1.0==1 1:int True; int widened to float
Simple strings ---
"Hello, world" "Hello, world":str
str(3.14) "3.14":str Overloaded str(:flt)
str(3) "3":str Overloaded str(:int)
str("abc") "abc":str Overloaded str(:str)
Variable lookup ---
math_pi 3.141592653589793:flt Should be math.pi but name spaces not implemented
primitive function lookup ---
+ "Syntax error; trailing junk" unadorned primitive not allowed
{+} {{+:{int int -> int}, +:{flt flt -> flt}} returns a union of '+' functions
{!} !:{int -> int1} function taking an int and returning a bool
Function application, traditional paren/comma args ---
{+}(1,2) 3:int
{-}(1,2) -1:int binary version
{-}(1) -1:int unary version
Errors; mismatch arg count ---
!() Call to unary function '!', but missing the one required argument
math_pi(1) A function is being called, but 3.141592653589793 is not a function type
{+}(1,2,3) Passing 3 arguments to +{flt64 flt64 -> flt64} which takes 2 arguments
Arguments separated by commas and are full statements ---
{+}(1, 2 * 3) 7:int
{+}(1 + 2 * 3, 4 * 5 + 6) 33:int
(1;2 ) 2:int just parens around two statements
(1;2;) 2:int final semicolon is optional
{+}(1;2 ,3) 5:int full statements in arguments
Syntax for variable assignment ---
x=1 1:int assignments have values
x=y=1 1:int stacked assignments ok
x=y= Missing ifex after assignment of 'y'
x=1+y Unknown ref 'y'
x=2; y=x+1; x*y 6:int
1+(x=2*3)+x*x 43:int Re-use ref immediately after def; parses as: x=(2*3); 1+x+x*x
x=(1+(x=2)+x) Cannot re-assign ref 'x'
Conditionals ---
0 ? 2 : 3 3:int Zero is false
2 ? 2 : 3 2:int Any non-zero is true; "truthy"
math_rand(1)?(x=4):(x=3);x :int8 x defined on both arms, so available after but range bound
math_rand(1)?(x=2): 3 ;4 4:int x-defined on 1 side only, but not used thereafter
math_rand(1)?(y=2;x=y*y):(x=3);x :int8 x defined on both arms, so available after, while y is not
math_rand(1)?(x=2): 3 ;x 'x' not defined on false arm of trinary No partial-defs
math_rand(1)?(x=2): 3 ;y=x+2;y 'x' not defined on false arm of trinary More complicated partial-def
0 ? (x=2) : 3;x 'x' not defined on false arm of trinary
2 ? (x=2) : 3;x 2:int Off-side is constant-dead, so missing x-assign is ignored
2 ? (x=2) : y 2:int Off-side is constant-dead, so "Unknown ref 'y'" is ignored
x=1;2?(x=2):(x=3);x Cannot re-assign ref 'x' Re-assignment not allowed
x=1;2? 2 :(x=3);x 1:int Re-assign allowed & ignored in dead branch
math_rand(1)?1:int:2:int :int8 no ambiguity between conditionals and type annotations
math_rand(1)?1::2:int missing expr after ':'
math_rand(1)?1:"a" Cannot mix GC and non-GC types
Anonymous function definition ---
{x y -> x+y} Types as a 2-arg function { int int -> int } or { flt flt -> flt }
{5}() 5:int No args nor -> required; this is simply a no-arg function returning 5, being executed
Identity mimics having type-vars via inlining during typing ---
id {A->A} No type-vars yet
id(1) 1:int
id(3.14) 3.14:flt
id({+}) {{+:{int int -> int}, +:{flt flt -> flt}}
id({+})(id(1),id(math_pi)) 4.141592653589793:flt
Function execution and result typing ---
x=3; andx={y -> x & y}; andx(2) 2:int capture external variable
x=3; and2={x -> x & 2}; and2(x) 2:int shadow external variable
plus2={x -> x+2}; x Unknown ref 'x' Scope exit ends lifetime
fun={x -> } Missing function body
mul3={x -> y=3; x*y}; mul3(2) 6:int // multiple statements in func body
x=3; addx={y -> x+y}; addx(2) 5:int Overloaded + resolves to :int
x=3; mul2={x -> x*2}; mul2(2.1) 4.2:flt Overloaded {+}:flt resolves with I->F conversion
x=3; mul2={x -> x*2}; mul2(2.1)+mul2(x) 10.2:flt Overloaded mul2 specialized into int and flt variants
sq={x -> x*x}; sq 2.1 4.41:flt No () required for single args
Type annotations ---
-1:int -1:int
(1+2.3):flt 3.3:flt Any expression can have a type annotation
x:int = 1 1:int Variable assignment can also have one
x:flt = 1 1:int Casts for free to a float
x:flt32 = 123456789 123456789 is not a flt32 Failed to convert int64 to a flt32
1: Syntax error; trailing junk Missing type
-1:int1 -1 is not a int1 int1 is only {0,1}
"abc":int "abc" is not a int64
x=3; fun:{int -> int} = {x -> x*2}; fun(2.1)+fun(x) 2.1 is not a int64
x=3; fun:{real -> real} = {x -> x*2}; fun(2.1)+fun(x) 10.4:flt real covers both int and flt
fun:{real->flt32} = {x -> x}; fun(123 ) 123:int Casts for free to real and flt32
fun:{real->flt32} = {x -> x}; fun(123456789) 123456789 is not a flt32
{x:int -> x*2}(1) 2:int types on parmeters too
{x:str -> x}(1) 1 is not a str
Recursive and co-recursive functions ---
fact = { x -> x <= 1 ? x : x*fact(x-1) }; fact(3) 6:int fully evaluates at typing time
fib = { x -> x <= 1 ? 1 : fib(x-1)+fib(x-2) }; fib(4) :int does not collapse at typing time
is_even = { n -> n ? is_odd(n-1) : 1}; is_odd = {n -> n ? is_even(n-1) : 0}; is_even(4) 1:int
is_even = { n -> n ? is_odd(n-1) : 1}; is_odd = {n -> n ? is_even(n-1) : 0}; is_even(5) 0:int
Simple anonymous structures ---
@{x,y} @{x,y} Simple anon struct decl
a=@{x=1.2,y}; x Unknown ref 'x' Field name does not escape structure
a=@{x=1,x=2} Cannot define field '.x' twice
a=@{x=1.2,y,}; a.x 1.2:flt Standard "." field name lookups; trailing comma optional
(a=@{x,y}; a.) Missing field name after '.'
a=@{x,y}; a.x=1 Cannot re-assign field '.x' No reassignment yet
a=@{x=0,y=1}; b=@{x=2}; c=math_rand(1)?a:b; c.x :int8 Either 0 or 2; structs can be partially merged and used
a=@{x=0,y=1}; b=@{x=2}; c=math_rand(1)?a:b; c.y Unknown field '.y' Used fields must be fully available
dist={p->p.x*p.x+p.y*p.y}; dist(@{x=1}) Unknown field '.y' Field not available inside of function
dist={p->p.x*p.x+p.y*p.y}; dist(@{x=1,y=2}) 5:int Passing an anonymous struct OK
dist={p->p.x*p.x+p.y*p.y}; dist(@{x=1,y=2,z=3}) 5:int Extra fields OK
dist={p:@{x,y} -> p.x*p.x+p.y*p.y}; dist(@{x=1,y=2}) 5:int Structure type annotations on function args
a=@{x=(b=1.2)*b,y=b}; a.y 1.2:flt Temps allowed in struct def
a=@{x=(b=1.2)*b,y=x}; a.y 1.44:flt Ok to use early fields in later defs
a=@{x=(b=1.2)*b,y=b}; b Unknown ref 'b' Structure def has a lexical scope
x*p.x+p.y*p.y}; dist(//qqq
5:int Some rather horrible comments
Named type variables Named types are simple subtypes
gal=:flt gal{flt -> gal:flt} Returns a simple type constructor function
gal=:flt; {gal} gal{flt -> gal:flt} Operator syntax for the function
gal=:flt; 3==gal(2)+1 1:int Auto-cast-away gal to get a flt
gal=:flt; tank:gal = gal(2) 2:gal
gal=:flt; tank:gal = gal(2)+1 3.0 is not a gal:flt No-auto-cast into a gal
Point=:@{x,y}; dist={p:Point -> p.x*p.x+p.y*p.y}; dist(Point(@{x=1,y=2})) 5:int type variables can be used anywhere a type can, including function arguments
Point=:@{x,y}; dist={p -> p.x*p.x+p.y*p.y}; dist(Point(@{x=1,y=2})) 5:int this dist takes any argument with fields @{x,y}, Point included
Point=:@{x,y}; dist={p:Point -> p.x*p.x+p.y*p.y}; dist( (@{x=1,y=2})) @{x:1,y:2} is not a Point:@{x,y} this dist only takes a Point argument
Nullable and not-null modeled after Kotlin ---
x:str? = 0 null question-type allows null or not; zero digit is null
x:str? = "abc" "abc":str question-type allows null or not
x:str = 0 "null is not a str"
math_rand(1)?0:"abc" "abc"? Null-or-string "abc"
(math_rand(1)?0 : @{x=1}).x Struct might be null when reading field '.x' Must be provable not-null
p=math_rand(1)?0:@{x=1}; p ? p.x : 0 :int1 not-null-ness after a null-check, so field de-ref is OK
x:int = y:str? = z:flt = 0 0:int null/0 freely recasts
"abc"==0 0:int Compare vs null
"abc"!=0 1:int Compare vs null
nil=0; "abc"!=nil 1:int Another name for 0/null
a = math_rand(1) ? 0 : @{x=1}; b = math_rand(1) ? 0 : @{c=a}; b ? (b.c ? b.c.x : 0) : 0 int1 Nested nullable structs
Recursive types ---
A= :(:A?, :int); A((0,2)) A:(nil,2) Simple recursive tuple
A= :(:A?, :int); A(A(0,2),3) A:(A:(nil,2),3) Simple recursive tuple
A= :@{n:A?, v:flt}; A(@{n=0,v=1.2}).v 1.2:flt Named recursive structure
A= :@{n:B?, v:int}; a = A(@{n=0,v=2}); a.n nil Unknown type B is never assigned, so no type error
A= :@{n:B, v:int}; B= :@{n:A, v:flt} B(@{n:A:@{n:B, v:int},v:flt} -> B) Types A and B are mutually recursive
List=:@{next:List?,val}; LL={n v -> List(@{next=n,val=v}) LL Linked-list type with sample shortcut factory
LL(LL(0,1.2),2.3) List:@{next:List:@{next:nil,val:1.2},val:2.3} Sample linked-list, with all types shown

Done Stuff

  • Static typing; types optional & fully inferred at every place.
  • Null-ptr distinguished; null/notnull types (e.g. Kotlin)
  • Duck-typing. Interfaces.
  • Functional; 1st class functions.
  • REPL
  • Dynamic code-gen; no seperate compilation step. Load Source & Go.
  • Limited overloads.
  • Overloading ops. No ambiguity / easy-to-read rules.
  • By default multi-arg ops are overloaded.
  • Direct SSA style code writing; no 'let' keyword.
  • default "x=1" makes a "val" until scope runs out (cannot re-assign)
  • Primitive values; int overflow OK;
  • Sub-byte ranges. Julia-like math typing.
  • Can type-name primitives, but no e.g. physical-unit-type math

Ideas, Desirables

  • H-M style typing.
  • JIT'ing.
  • {GC,Ref-Counting}: Ponder both vs requiring e.g. lifetime management (easy by just raising scope).
  • No exceptions?!!? Same as Elm: allow tagged union returns with an error return vs a non-error return. Force user to handle errors up&down the stack.
  • Lexical scope destructors.
  • Can ask for Int for BigInteger; unboxed arrays.
  • Pattern-matching too handy looking, need to have it
  • Parallel (and distributed) but also deterministic
  • "eval"
  • Monads? i/o, side-effect monads.


  • Distributed ref-cnting? (or Dist-GC?)
  • Ref-Counting does NOT given "immediate" destructor execution, but "soon".
  • Guaranteed to count down & release before the next instance of exact same constructor constructs?
  • Guaranteed to count down & release before the next loop backedge? Before base of containing loop?
  • Built-in "pools" for bulk-remove? Same as ref-counting.
  • Rust-style memory lifetime management; linear logic owner; borrowing; guaranteed death


  • Pony-style concurrency management
  • CAS built-in lang primitive: 'res := atomic(old,new)'; JMM
  • CPS for threads/concurrency;
  • not really actors but spawn/fork worker threads, run until they 'join' with parent.
  • Transactions-for-shared-memory-always (Closure style)

types and name spaces and nulls:

  • OOP namespaces (distinguished "this"; classes; single-inheritance vs interfaces)
  • Modules: independent shipping of code.
  • Elm-style union types
  • Single inheritance (or none; composition also works).
  • physical-unit-types, esp for arrays; e.g. "fueltank_size:gallon", and "speed:mile/hour", with auto-conversions

performance types:

  • performance types: "no autoboxing, no big-int, no dynamic dispatch, no serial loops?"
  • also: No GC allocations (only ref-counting & rust-style lifetime management).
  • Runs in "O(1) time"? Runs in "O(N) time"?
  • associated affine-value types: "this int is equal to that int, plus or minus a constant".
`fun copyInt2Dbl( src:[]int32, dst:[src.len+0]d64 )...`


`fun copyInt2Dbl( len:int32, src:[len]int32, dst:[len]d64 )...`


`fun slide( len:int32, off:int32, src:[>=len]a, dst[>=len+off]a )...`

maps & parallel loops:

  • maps-over-collections; default to parallel
  • parallel/distributed collections; deterministic
  • maps-with-folds require a associative fold op (and will run log-tree style)
  • maps-without-assoc-folds are serial loops: code it as a loop
  • user-spec'd iter types; for-loop syntax-sugar

serial loops:

  • For-loops with early-exit and Python else-clause
for( foo in foos )
  if( isAcceptable(foo) )
  else return DidNotFindItError()
  • To detect never-ran vs ran-but-not-exited:
    if( foos.empty() ) return foos_was_empty
      for( foo in foos )
        if( isAcceptable(foo) )
      else return no_acceptable_in_foos()


  • embed 'fact' in string: "milage=%(dist/gals) mph". The expression (dist/gals) is a standard paren-wrapped 'fact' from the grammar.
  • multi-value-returns OK, sugar over returning a temp-tuple
  • Extra "," in static struct makers OK: "{'hello','world',}"
  • Tail-recursion optimization.
  • "var" can be reassigned but requires type keyword: "x:= 1"

Getting started

Download dependencies:

make lib



Run checks:

make check

Launch the REPL:

java -jar build/aa.jar