hoc is a command-line calculator directly inspired by Kernighan and Pike[1].
The structure of the input accepted by hoc is specified by a formal
grammar, and the Look-Ahead Left-Right parser for this grammar
is automatically generated by yacc[2].
The accompanying low-level input lexical analyzer for hoc is written in Go,
thus goyacc is used as the parser-generator to generate a Go parser
and control the input process.
A feature of hoc is that it supports 64-bit floating point values
as opposed to simple 64-bit integer values. Thus a possible name
for the program could be fhoc, but I'll leave that as an exercise for the
reader who forks the project.
- sin, asin
- cos, acos
- tan, atan
- log, log2, log10
- sqrt, exponentiation with
^ - PI
todeg,torad
# As of go 1.20.2:
$ go install golang.org/x/tools/cmd/goyacc@latest
$ cd src/github.com/jfinken/hoc
$ goyacc -o hoc.go -p Hoc hoc.y
$ go mod tidy
$ go install
# As of early versions of go:
$ go get golang.org/x/tools/cmd/goyacc
$ go get github.com/chzyer/readline
$ goyacc -o hoc.go -p Hoc hoc.y
$ go build
then:
$ hoc
hoc> 2.35 * 4.5
10.5750
hoc> a = 2*1024*1024
hoc> a
2097152.0000
hoc> a / 2048
1024.0000
hoc> acos(-1)
3.1416
hoc> a = 4^2; sqrt(a)
4.0000
hoc> 2*PI*todeg
360.0000
- B. W. Kernighan and R. Pike, The UNIX Programming Environment, AT&T Bell Labs, Prentice-Hall, 1984.
- S. C. Johnson, Yacc: Yet Another Compiler-Compiler, AT&T Bell Labs, Murray Hill, New Jersey.