On both Squeak 3.9 (I supose others too) and Pharo: Fraction readFromString: '1/2' ---> 1 '1/2' asNumber ---> 1 fix Number #readFrom: stringOrStream "Answer a number as described on aStream. The number may include a leading radix specification, as in 16rFADE" | value base aStream sign | aStream _ (stringOrStream isString) ifTrue: [ReadStream on: stringOrStream] ifFalse: [stringOrStream]. (aStream nextMatchAll: 'NaN') ifTrue: [^ Float nan]. sign _ (aStream peekFor: $-) ifTrue: [-1] ifFalse: [1]. (aStream nextMatchAll: 'Infinity') ifTrue: [^ Float infinity * sign]. base _ 10. value _ Integer readFrom: aStream base: base. "this line " (aStream peekFor: $/) ifTrue:[^Fraction numerator: value denominator: (aStream upTo: $\) asInteger]. " added " (aStream peekFor: $r) ifTrue: ["<base>r<integer>" (base _ value) < 2 ifTrue: [^self error: 'Invalid radix']. (aStream peekFor: $-) ifTrue: [sign _ sign negated]. value _ Integer readFrom: aStream base: base]. ^ self readRemainderOf: value from: aStream base: base withSign: sign. -- Norberto Manzanos Instituto de Investigaciones en Humanidades y Ciencias Sociales (IdIHCS) FaHCE/UNLP - CONICET Calle 48 e/ 6 y 7 s/Nº - 8º piso - oficina 803 Tel: +54-221-4230125 interno 262