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To get started with Funnel you should copy the file
/home/linuxsoft/funnel/lecture/intro.fn
to your home account. It contains an implementation
of the function sqrt defined in the first
lecture. You can test this function by invoking the funnel
interpreter funni with the -untyped
option: funni -untyped intro.fn.
You enter an interpreter loop which accepts Funnel
expressions as input, evaluates these expressions and
prints out the result of the evaluation. You can exit
the interpreter by entering :q. Command
:h gives you an overview over all interpreter
commands.
Alternatively to the interpreter you can use the Funnel
compiler funnelc directly. It compiles a Funnel source file
intro.fn to a bytecode file intro.net.
Do not forget to specify the -untyped option again
when compiling dynamically typed Funnel programs.
For executing the compiled binary, the Funnel virtual
machine funnel has to be invoked: funnel intro.
After getting familiar with the environment you should
start implementing complex numbers using records. For this task
you can copy a framework as well from
/home/linuxsoft/funnel/lecture/complex.fn.
Your complex
number datatype should support the functions real, imag, plus, minus,
times, div, abs, conjugate and toString:
-
real and imag return the real or
imaginary part of the complex number,
-
plus, minus, times and div implement
basic arithmetic operations,
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abs returns the absolut value of the complex number,
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conjugate calculates the complex conjugate, and
-
toString returns a string representation of the
complex number. Like in Java, you can use the + operator
for string concatenation if one of the operands is a string.
Operands not beeing a string are automatically converted into
a string.
Here is a transcript of a funni session in which the
complex datatype is used:
> val I = makeComplex(0, 1)
'val I = [record id=1, adr=0, type=(real, imag, plus, minus, times, div,
abs, conjugate, toString)]'
> I.times(I).toString
"(-1, 0)"
> val t = makeComplex(4, 7).times(makeComplex(3, -1))
'val t = [record id=1, adr=0, type=(real, imag, plus, minus, times,...]'
> t.toString
"(19, 17)"
> t.div(makeComplex(5, 2)).times(makeComplex(5, 2)).toString
"(19.000002, 17.0)"
> sqrt(t.times(t.conjugate(t)).real)
25.495098
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