design.txt

# halftau design

elts
	null		null
	integer		64 bit integer
	double		64 bit float
	string		(immutable) UTF-8 string
	char		UTF-8 character
	byte		8-bit byte
	list		pair of head, tail			[seq]
	vector		(immutable) array of fixed size		[seq]
	hashmap		(immutable) mapping of key -> value
	set		(immutable) deduplicated set of keys
	keyword		things like :a, :b, :c
	symbol		things like 'a, 'b, 'c

syntax notes
	null		null
	1		integer
	1.		double
	1e5		double
	'(1 2)		list
	[1 2]		vector
	{:a 1}		map
	#{:a}		set
	"string"	string
	'c'		char
	#(+ 1 %)	lambda
	[x & ys]	expands to [x y1 y2 y3]
	; text		comment

interpreter builtin functions (core)
	head		return first elt of seq
	tail		return all elts after head of seq
	cons		return head attached to list tail
	nth		return nth elt of seq or nth char of string
	null?		true iff value is non null
	truthy?		true iff value is neither null nor false
	=		true iff values are recursively identical
	map		apply fn to each elt of seq
	parallel-map	apply fn to each elt of seq in numCPU threads
	filter		filter seq by fn (always returns list)
	parallel-filter	filter seq by fn in numCPU threads (always returns list)
	->		thread-first macro
	->>		thread-last macro
	str		converts elts to string representation and concats
	char		return unicode char
	count		return size of seq or string (strings: chars, not bytes)

interpreter builtin functions (extended)
	io/slurp	returns contents of file in filename
	io/spit		write string to file
	io/append	append string to file
	str/cat		concatenate all strings together
	str/substr
	str/contains