happy-space

this is a command-line calculator. it supports

• the infix operations +, -, *, /, %, ^
• the prefix operators ~ (negate) and ! (factorial)
• conventional operator precendence
• parentheses
• whitespace precedence

that's right!

> 3+6/3
5
> 3 + 6/3
5
> 3+6 / 3
3

but:

> 1+ 2
(line 1, column 4):
unexpected whitespace after `+`
> 1 +2
(line 1, column 4):
unexpected "2"
expecting space after `+`

• ghc
• make
• dash (for tests)

run make in the top level of the repo. this will create bin/hscalc.

if you experience problems with linking, you can try make HSFLAGS=-static.

you can also make test, if you have the appropriate dependencies.

there are three ways to invoke hscalc:

• running hscalc will produce an interactive repl;
• hscalc "1+2" will evaluate all the expressions passed as arguments;
• hscalc - will read once from standard input and evaluate that.